Planar Chromatography - ACS Publications - American Chemical

Anal. Chem. 1996, 68, 1R-19R

Planar Chromatography Joseph Sherma

Department of Chemistry, Lafayette College, Easton, Pennsylvania 18042 Review Contents General Considerations History, Books, Reviews, and Student Experiments Theory and Fundamental Studies Chromatographic Systems (Stationary and Mobile Phases) Apparatus and Techniques Detection and Identification of Separated Zones Quantitative Analysis Preparative-Layer Chromatography and Radio-Thin-Layer Chromatography Applications Acids and Phenols Amino Acids, Peptides, and Proteins Antibiotics Bases and Amines Carbohydrates Dyes and Pigments Hydrocarbons Lipids Pesticides Pharmaceuticals, Drugs, and Alkaloids Purines, Pyrimidines, and Nucleic Acids Steroids Surfactants Toxins Vitamins Miscellaneous Organic Compounds Inorganics and Metal Organics Literature Cited

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This is a selective review of the literature of thin-layer chromatography (TLC) and paper chromatography (PC) cited in Chemical Abstracts from November 1, 1993 to November 1, 1995. The literature search was augmented by consulting Analytical Abstracts, Chemical Titles, and Current Contents, and the following important journals publishing papers on TLC and PC were searched directly: Journal of Chromatography (parts A and B and the bibliography issues), Journal of Chromatographic Science, Chromatographia, Analytical Chemistry, Journal of Liquid Chromatography, Journal of AOAC International, Journal of Planar Chromatography-Modern TLC, and Acta Chromatographica. Publications in the past two years on the theory, techniques, and applications of TLC continued at a high level, but only a very small number of papers reported new research in PC. The attempt was made to cite only the most important publications describing significant advances in theoretical studies, methodology, instrumentation, and applications. The review is mostly limited to journals easily accessible to U.S. scientists. This eliminates coverage of many papers in foreign-language journals, especially Chinese, Japanese, Polish, and Russian. Abstracts citations are given for references from the more obscure journals and papers not published in English. Although TLC was applied during the past two years in many fields, including environmental, agroS0003-2700(96)00001-7 CCC: $25.00

© 1996 American Chemical Society

chemical, industrial, food, flavors, cosmetics, clinical, forensic, biochemical, and biomedical analysis, as usual, the greatest number of papers were published on the analysis of pharmaceuticals and drugs. Most TLC papers originated from laboratories outside of the United States, especially Europe and Asia. TLC is a very widely used chromatographic technique, but most of its applications are in the form of conventional qualitative TLC rather than modern, quantitative, instrumental high-performance TLC (HPTLC). In fact, a source at one of the world’s leading plate manufacturing companies informed me that the vast majority of their sales are plain silica gel TLC plates rather than high-performance, channeled, or preadsorbent silica gel or bonded silica gel phases. Conventional TLC allows fast, inexpensive, qualitative and semiquantitative analyses in the laboratory or field with minimal operator training required. An example is monitoring synthetic reactions by organic chemists. Modern quantitative HPTLC, when properly performed by well-trained analysts, can be advantageous compared to high-performance liquid column chromatography (HPLC) or gas chromatography (GC) in many analytical situations. Special advantages of TLC include high sample throughput and low cost per analysis; multiple samples and standards can be separated simultaneously, and sample preparation requirements are often minimal because the stationary phase is disposable. Other advantages of TLC compared to HPLC include static, off-line detection of zones using a great variety of complementary postchromatographic universal and selective detection methods that are often applied sequentially, and storage of the separation, containing all sample components, on the layer for identification and quantification at a later time by in situ or elution methods. Two important reviews published in 1995 outlined the latest trends in modern instrumental TLC. Poole and Poole (1) discussed multidimensionality in planar chromatography, including theoretical aspects of planar separations, unidimensional multiple development, two-dimensional development, and planar chromatography coupled with GC, supercritical fluid extraction and chromatography, and liquid chromatography. Somsen et al. (2) reviewed planar chromatography coupled with electron impact, chemical ionization, liquid secondary ion, fast-atom bombardment (FAB), and laser desorption mass spectrometry (MS), MS/MS, and Fourier transform infrared (FT-IR), Raman, and fluorescence spectrometry. Busch (3) compared costs of determinations by planar and column chromatography assuming three scenarios: compound screening, drug metabolite, and complex mixture analysis. Personnel and instrument costs were considered, and it was concluded that multiple and parallel sample separation can be particularly advantageous for TLC determinations with a large number of samples. The cost advantage of TLC was shown to be significant when a large number of repetitive analyses are performed. The Eighth International Symposium on Instrumental Planar Chromatography was held in Interlaken, Switzerland, April 5-7, Analytical Chemistry, Vol. 68, No. 12, June 15, 1996 1R

1995. Lectures presented at this symposium, which illustrate many of the important current research areas in techniques and applications, were reviewed by Davies (4). The topics of these lectures included the following: correct calibration and evaluation of analyses; identification assurance using chromatographic and spectroscopic data; comparison of solvent optimization methods; new aluminum-backed amino-bonded sheets; horizontal developing chamber for TLC with a moving plate for altering the solvent entry position; drug screening in forensic toxicology; sample cleanup by overpressured layer chromatography (OPLC); distribution of poly(oxyethylenic) oligomers in poly(oxyethylene) glyceryl trioleate; determination of the quality of spices and flavors; quality control of long-term stored drugs; validation of quantitative TLC in pharmaceutical analyses; effects on TLC of temperature, humidity, and other experimental conditions; toxicological evaluation of harmful substances by in situ enzymatic detection; advances in HPTLC/MS and HPTLC/MS-MS; vibrational spectrometric detection techniques for characterization of compounds on layers; and validated trace soil analysis. There were also two papers given at the symposium on electroplanar chromatography (electrophoresis), and posters presented included new applications of TLC in cosmetics, food, pharmaceutical, drug, and environmental analysis. In an editorial summarizing this symposium (5), Kaiser offered the following thoughts on the current state and future of planar chromatography. Fully instrumental planar chromatography performed properly is the most economic, powerful, and accurate quantitative analytical method for mixtures of soluble substances of low vapor pressure. Although the instruments are expensive, the low cost per analysis repays the initial investment after a short period of application. HPLC is an ideal sample pretreatment step for analysis by planar chromatography, which offers accuracy, economy, speed, numerous means of detection including in situ spectroscopy, and sensitivity down to parts-per-trillion (ppt) levels. He predicted the future commercial availability of software to correct a major systematic error, plate structure, and mentioned two new scanners exhibited at the symposium, one a fully computerized image processing instrument that is independent of the separation mode used. This instrument will allow use of circular development for quantitative analysis, which is more powerful than linear development. The next instrumental planar chromatography symposium will again be held in Interlaken, in April 1997. Layer manufacturers have made serious efforts to improve the performance and reproducibility of precoated layers. One manufacturer now offers silica gel 60 HPTLC plates with an imprinted identification code, which are suitable for the practice of GLP/ DIN ISO standards. Training courses were offered periodically in Wrightsville Beach, NC by Camag (instrumental TLC) and at different locations throughout the United States by Analtech (video densitometry and documentation). Camag offers a bibliography service (CBS) to keep subscribers informed about publications involving TLC, and Merck has available a computer teaching program and user’s handbook on modern thin-layer chromatography. Issue 4 of Vol. 7 of the Journal of Planar ChromatographyModern TLC was in memorium the late Prof. Dr. Helmut Jork, an internationally recognized pioneer of quantitative TLC. Professor Jork’s impressive accomplishments in research, teaching, and 2R

Analytical Chemistry, Vol. 68, No. 12, June 15, 1996

promotion of TLC were summarized in an obituary written by Dieter Jaenchen (6). GENERAL CONSIDERATIONS History, Books, Reviews, and Student Experiments. Friedlieb Runge’s experiments on circular paper chromatography, which were precursors of modern planar chromatography, were summarized on the occasion of the bicentenary of his birth in 1994 (A1). The second volume in a series of books on detection reagents and methods was published (A2). The second edition of the Handbook of Thin Layer Chromatography containing 14 chapters on principles and practice and 17 chapters on applications to specific compound classes (A3) and a new book containing an introductory chapter on techniques and instrumentation and 11 chapters on TLC applications in various important biological and chemical disciplines such as food analysis and bacteriology (A4) are in press. Review articles were published on the following topics: new separation techniques (A5), hyphenated coupling techniques involving TLC (A6), modern HPTLC techniques and applications (A7), TLC in environmental analysis (A8), uses of TLC in the coal and oil industries (A9), and quantitative TLC in forensic science (A10). Other pertinent reviews are cited in the sections below. Laboratory experiments for high school and college students were devised to illustrate the use of TLC for the analysis of aspirinfree analgesic tablets (A11), separation of dyes (A12), and hydrolysis of glutathione and TLC of amino acids (A13, A14). A two-part investigative experiment for organic chemistry laboratory courses was designed to analyze biologically active components of seaweed by use of extraction, TLC, and biological activity tests (A15). A miniaturized UV-transparent TLC chamber for viewing separated colored, fluorescent, and UV-absorbing spots during lecture demonstrations was described (A16). Theory and Fundamental Studies. Statistical theories of peak overlap in one-dimensional or multidimensional separations by TLC, electrophoresis, or capillary chromatography were reviewed (B1). Partition coefficients and chromatographic parameters of some substituted 1,3-thiazolidin-4-ones were determined (B2). Results of a comparative study of the effect of an increased number of CH2 groups in chelate rings of transition metal complexes during salting-out TLC were consistent with the mechanism of nonspecific hydrophobic interactions (B3). It was demonstrated that informational theory, which is a simpler parameter than entropy in its mathematical expression, has a resolution character very similar to entropy and may be efficiently used in TLC studies (B4). Diffusion, evaporation, specific heats, and adsorption energies of ternary mobile phases containing ethyl acetate, chloroform, and tetrahydrofuran (THF) and silica gel plates were evaluated, and it was concluded that diffusion and evaporation rates were highest when the proportion of chloroform in mixtures was largest and that ethyl acetate was best adsorbed by silica gel (B5, B6). The interaction of amino acids with ethyoxylated stearic acid surfactants was studied by chargetransfer reversed-phase (RP)-TLC, and the relative strength of interaction was calculated (B7). A coadsorption effect was observed in a liquid-solid TLC system containing silica with binary eluents dioxane-heptane or ethyl acetate-heptane using a horizontal DS chamber (B8). The position of the initial zone was found to have a major influence on the average plate height and could be optimized; the Guiochon and Siouffi model was

shown to greatly underestimate the plate height for low values of the starting position (B9). Topological indexes were applied in the following studies: prediction of RM values of isomeric alcohols on silica gel 60 layers with carbon tetrachloride-diethyl ether-ethyl acetate (8:2:1) mobile phase (B10); determination of RM values of isomeric phenol derivatives on silicone-impregnated silica gel G with veronal acetate buffer (pH 7.4)-acetone (65:35 and 60:40) mobile phase in structure-biological activity studies (B11); description of a new stereoisomeric topological index for predicting the separation of stereoisomers with hydroxyl groups in axial and equatorial positions on silica gel developed with hexane-ethanol (85:15) or benzene (B12); ability of the molecular connectivity model to predict Rf values for a group of sulfamides (B13); differentiation of alkanolamine properties by multivariate analysis of a database containing their molecular parameters and Rf values in RP-TLC and PC systems (B14, B15); and structure-activity investigation of benzoic acid derivatives based on RM values (B16). The following theoretical and experimental studies of solute retention in TLC were published: chemometrically aided description of the retention of 12 iminodiethanol congeners using 26 RP phases comprising three different silica gel layers with varied hydrocarbonaceous modification and methanol-water or acetonitrile-water mobile phases (B17); azines and diazines with RP bonded alkyl layers and methanol-water eluents (B18) or silica gel and propanol-hexane eluents (B19); 4-cyanophenyl herbicides on water-soluble β-cyclodextrin (β-CD) support (B20); 38 nonionic surfactants by RP-TLC using alumina support and methanol as an organic modifier (B21); 17 monoamine oxidase inhibitory drugs in various adsorptive and RP-TLC systems (B22); a variety of solute types in adsorption TLC with aliphatic alcohol-hexane eluents (B23); charged and uncharged racemic solutes on RP18W plates developed with solutions of different pH containing 2% 2-propanol and high concentrations of bovine serum albumin (B24); dependence of retention and separation quality on the properties of different weak solvents in each of a series of binary mobile phases containing an appropriate concentration of a common strong solvent (B25); RP-TLC with THF-, acetone-, and acetonitrile-phosphate buffer eluents (B26, B27); and heteroazophenols in Florisil, silica, and alumina normal-phase systems (B28, B29). RM values were used as the basis of studies on the effect of electronegativity of donor atoms on migration of tris(β-diketonato) complexes of Co(III), Cr(III), and Ru(III) on silica gel (B30); comparison of the behavior of azines and diazines in Florisil and aluminum oxide (B31); the relationship between the physicochemical parameters of 3,5-dinitrobenzoic acid esters and their retention on β-CD polymer support (B32); determination of a linear relation between RM obtained in salting-out TLC on silica gel, polyacrylonitrile, and cellulose layers for mixed aminocarboxylatocobalt(III) complexes and mole percent of ammonium sulfate in the aqueous solvent systems (B33, B34); and the relationship between capacity factors and mobile phase composition in thin-layer ligand exchange chromatography of amino acid enantiomers (B35). The following studies of mobile-phase optimization were reported: the use of interpretive methods for adsorption TLC with alcohol-hydrocarbon eluents (B36); a simple, fast, and inexpensive method for adsorption TLC based on seven simultaneous experiments using isocratic multicomponent mobile phases (B37);

optimization of quaternary mobile phases from data obtained using binary and ternary mixtures (B38); comparison of the efficiency of the Snyder, Schoenmakers, and Kowalska methods for optimizing RP-TLC with C-2 bonded silica layers and methanol-water binary eluents (B39); computer simulation of the separation in one- and two-dimensional (2-D) TLC by isocratic and stepwise gradient development (B40); use of a graphical method with a computer program for 57 solutes separated with 16 binary eluents (four diluents and four modifiers) (B41); optimization of stepwise gradient HPTLC by statistical scanning (B42, B43); integration of four computer-assisted methods to produce an improved optimization system (B44); computer-assisted optimization of the separation of eight pesticides by 2-D HPTLC (B45); and optimization of the HPTLC separation of a mixture of unknown composition by recognition of the order of the spots by comparison of spot areas and data from UV absorption spectra of the spots, followed by application of the Monofactor Optimization System (B46). The use of TLC sandwich chambers for theoretical prediction of mixture separation in HPLC was studied by thermodynamic treatment using a linear form of Oscik’s equation (B47). Two methods of using TLC data for mobile-phase optimization in HPLC were reviewed, the first involving experimental correlation TLC and column retention parameters and the second based on thermodynamic description of adsorption systems with mixed mobile phases (B48). A unique way of graphically displaying and correlating RP-HPLC retention times with TLC Rx values, which exploited the orthagonal nature of the different chromatographic selectivities, was valuable in the development of pharmaceutical compounds (B49). The relationship between the HPLC and TLC retention of 26 nonhomologous pesticides with alumina stationary phases and hexane-dioxane mobile phases was determined, and the predictive power of TLC for HPLC was found to be low (B50). OPLC was compared with TLC and HPLC with reference to the composition of the mobile phase for analysis of coumarins, and it was shown that OPLC and TLC were closely related while HPLC showed a different behavior in the elution process with regard to solvent strength (B51). The basic aspects and relationship between slope and intercept of TLC equations for determining lipophilicity by RP-TLC were reviewed (B52). A hydrophobicity parameter, RMw, was described to permit the determination of TLC lipophilicity parameters on the basis of thermodynamically true RM values; methanol was shown to be the best mobile phase modifier (B53). RP-TLC was used in the following investigations of compound lipophilicity: ionizable quinolone derivatives on silicone-impregnated silica gel with mobile phases containing acetone, methanol, or acetonitrile as the organic modifier (B54); plant growth-stimulating amido esters of ethanolamine on C-18 bonded silica gel with methanolwater mobile phase (B55); nonhomologous anticancer drugs using seven different mobile-phase organic modifiers (B56); 16 bioactive heterocyclic compounds (B57); steroids (B58); and morphine derivatives on paraffin-impregnated silica gel with methanol-water mobile phases (B59). Chromatographic Systems (Stationary and Mobile Phases). Measures taken for quality assurance in preparation, manufacture, and marketing of silica gel layers that are in compliance with good laboratory practice (GLP) were described (C1). Recommendations were given for initial treatment, prewashing, activation, and conditioning of foil- and glass-backed thin layers (C2). Mixed Analytical Chemistry, Vol. 68, No. 12, June 15, 1996

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C-18/cyano (C3) and C-8/diol (C4) layers for 2-D TLC were prepared and evaluated for chromatographic behavior and mechanism and compared by chromatography of some polycyclic aromatic hydrocarbons. A microwave oven was used to condition silica gel and argentation TLC plates in a fraction of the time normally required (C5). The high reproducibility of silica gel 60 precoated plates in TLC and HPTLC was demonstrated (C6). The performances of silica gel layers composed of 3 and 5 µm particles for OPLC were compared (C7). The following new stationary phases were described and characterized: plates made by a molecular imprinting techniques and used for the chiral separation of L- and D-phenylalanine anilide (C8); n-octyl-bonded volcanic tuff (C9); Cu(II)-impregnated silica gel for separation of glucose and sorbitol (C10); and silica gel impregnated with various metal ions for the analysis of inorganic pollutants (C11, C12). Thermoanalysis was used to study the distribution of different TLC impregnating agents, such as paraffin oil, 1-octanol, tricaprylmethylammonium chloride, EDTA, and boric acid, on silica gel (C13). Forced-flow TLC was used to characterize the kinetic properties of silica gel plates from different manufacturers in terms of porosity, apparent particle size, flow resistance, relation between reduced plate height and reduced velocity, and separation impedance (C14). The use of micellar solutions of anionic and cationic surfactants as mobile phases was found to result in dynamic modification of the silica gel surface, which acquires the properties of a reversed phase in the separation of fluorescein derivatives (C15). The TLC retention of 26 model compounds on silica gel was compared using a homologous series of ethers and ketones as mobile phases; retention was found to increase uniformly for solutes of analogous structure but less regularly, with changes in selectivity, for solutes with different structures (C16). General aspects of adsorption chromatography on cellulose were studied with aqueous solutions of R-cyclodextrin (C17) and carbohydrates (C18) as eluents. The addition of cyclodextrins in the mobile phase enhanced the migration of p-nitroanilines and their analogs on silica gel and polymer layers (C19). A model of a unified adsorption center was proposed that provides a means of judging the relative eluent strength of mobile-phase components for various types of sorbents (C20). Alkaloids were separated by ion-pair RP-TLC using silanized silica gel either alone or containing a counterion as adsorbent and phosphate buffer-organic modifier mixtures containing low concentrations of anionic ion-pairing reagent as a mobile phase (C21). Optical and structural isomers were separated in the following systems: C-18 layers and eluents containing modified β-CDs for separation of isomers of amino acids, alkyltryptophans, benzamides, and naphthols (C22); cellulose with cyclodextrin eluents for the chiral separation of tryptophan and fluoro- and methyltryptophans (C23); racemates and pure optical isomers on acetylated cellulose developed with aqueous-organic mobile phases containing ethanol or 2-propanol (C24); isomers of chlorobenzoic acid, phenylphenol, dinitroanilines, and naphthols utilizing aqueous or aqueous methanolic solutions of micelle-mimetic intramolecular ionene aggregates in pseudophase TLC (C25); and racemic drugs, dansyl amino acids, and 6-(aminoquinolyl)-N-hydroxysuccinimidyl carbamate-derivatized amino acids using the macrocyclic amino acid vancomycin as a chiral mobile-phase additive with acetonitrile modifier and a diphenyl-bonded silica layer (C26). 4R


Apparatus and Techniques. A review was written on instrumental TLC, which offers automation, reproducibility, and accurate quantification and application to a wide variety of analyses (D1). A new HPTLC tank designed to give optimal saturation conditions resulting in highly reproducible chromatograms was applied to separations of gangliosides and neutral glycosphingolipids (D2). The horizontal DS chamber allows isocratic, gradient, and multiple development, as well as simultaneous development using different eluents under different conditions; optimization of the separation of plant extracts (D3) and quantification of Frangula anthraquinones by densitometry (D4) were carried out using this chamber. A 2-D Hadamard encoding mask was applied for imaging TLC plates by laser-induced fluorescence or surface-enhanced Raman scattering and for use with a photoacoustic detector to generate three-dimensional photoacoustic images (D5). A new device for OPLC with a final pressure drop of 140 bar consisted of flat, ground stainless steel blocks and a water cushion system (stainless steel or Mylar membrane) mounted in a hydraulic press (D6). A video image archival system for documentation of chromatograms was described (D7). The mechanism and applications of unidimensional multiple development in TLC were reviewed, including solvent selectivity, automation, and solvent gradients; it was shown that maximum separating power in isocratic development occurs when the distance between the solvent entry and sample application positions is minimized and when the solvent entry position and the solvent front are incremented at each development step (D8). A collaborative study compared the usual procedures, spraying and dipping of detection reagent, with overpressured derivatization (D9), which entails pressing a pad of polymeric foam containing the reactive solution on the plate to obtain its complete and homogeneous distribution, for visualization of amino acids, sugars, and other compounds (D10). Methods for eliminating fundamental problems associated with OPLC, including the correct preparation of the plate, selection of the mobile phase, inlet pressure, and cover (Teflon) plate, and elimination of the result of the “multifront effect” and the “disturbing zone”, were discussed (D11). TLC on high-performance silica gel plates with a stepwise ethyl acetate-methanol gradient was used to separate glycosides isolated from Digitalis species (D12). Classical and forced-flow displacement TLC were compared for separation of some ecdysteroids; combined elution-displacement TLC was also performed using forced flow (D13). True color photodocumentation of UVirradiated chromatograms was obtained by first employing color slide film for selection of appropriate filters and exposure data, followed by the making of color prints with color negative film using the previously optimized conditions (D14). A new PC hybridization assay (PACHA), based on migration of DNA on a nitrocellulose strip passing through an immobilized probe area, was faster and simpler to use than the conventional dot hybridization assay (D15). Affinity thin layer chromatography (ATLC), which combines the use of a solid-phase-bound antigen and conventional TLC, was shown to be a simple, rapid, and selfcontained system for assaying the immunoreactive fraction of radiolabeled antibodies (D16). Thin-layer immunoaffinity chromatography with bar code quantification was used to assay C-reactive protein in serum (D17). Sendai viruses (HNF1, Z-strain) were determined by two direct solid-phase binding assays: the overlay technique, which combines HPTLC of gangliosides with direct binding, and the microwell adsorption assay;

both analyses were found to be equivalent tools for ganglioside receptor studies (D18). A new type of 2-D HPTLC, TLC mapping, was used to analyze acid glycosphingolipids; the method involves separation by development with chloroform-methanol-1% diethylamine (50:47:15) on an amino-bonded silica gel plate, transfer of the analytes to a silica gel plate by development with chloroformmethanol-ammonia (2:5:3) after placing the plates layer to layer, and then another separation by development on the silica gel layer with chloroform-methanol-0.2% CaCl2 (D19). Coupling techniques for TLC with spectroscopic and biochemical methods were reviewed (D20). Rare earth elements in granites and greisens were determined with a 0.25-5 ppm detection limit and 0.04-0.08 relative standard deviation using TLC preconcentration followed by inductively coupled plasma atomic emission spectrometry; TLC had advantages over column chromatography methods in that a small initial mass and small aliquots of solution can be used (D21). Pharmaceutical analyses were successfully performed by coupled TLC/HPLC, in which the column effluent was directly spotted onto plates (D22). Identification of irradiated fat-containing foods by determination of 1,2-unsaturated hydrocarbons and 2-alkylcyclobutanones as fat radiolysis products was performed by isolation from the food, derivatization, labeling with a fluorophore, and coupled TLC/ HPLC (D23). Hydroperoxides in solid matrixes were detected using supercritical fluid extraction (SFE) with online sample transfer, and the technique was applied to the investigation of combustion aerosols (D24). Automation of TLC was discussed in the following papers: application of robotics (D25); an open software environment to optimize the productivity of robotized laboratories (D26); and use of an automatic spotter managed with a personal computer for reproducible application of nanoliter to microliter sample volumes in compliance with GLP (D27). Detection and Identification of Separated Zones. Unknown zones on TLC plates were reliably identified by use of retention data measured in characterized mobile phases (E1). HPTLC coupled online with spectroscopic methods such as ultraviolet-visible (UV-vis), FT-IR, and Raman were shown to be valuable reference methods in clinical chemistry for identification of zones and unequivocal diagnosis as the basis for further clinical therapeutic measures (E2). The following detection reagents and methods were described: conversion of substances such as organic acids into fluorescing derivatives using reagent-free heat activation on aminomodified silica gel layers (E3); detection of steroids as fluorescent zones on amino layers with 5 ng/spot sensitivity by dipping chromatograms into a hexane-paraffin mixture and using filters that cut emission wavelengths below 400 nm (E4); 2-(chloromethyl)benzimidazole as a selective chromogenic reagent for detection of azoles (E5); trifluoroacetic anhydride-sodium iodide reagent for differentiation of nitrones, nitroxide radicals, and nitrosamines (E6); a spray reagent for screening of biological materials for the presence of carbaryl insecticide (E7); the Forrest reagent to detect phenothiazines and impipramine and its derivatives for diagnosis of intoxication with these drugs (E8); and eosin yellow, bromothymol blue, thymol blue, helasol green, SPADNS, and titanium yellow for quinoline, isoquinoline, and 6-, 7-, and 8-methylquinoline on silica and alumina plates (E9). TLC blotting (E10), a method in which compounds are blotted from an HPTLC plate to a poly(vinylidene difluoride) (PVDF)

membrane, was shown to detect glycolipids and phospholipids more sensitively than could be accomplished directly on the layer by chemical visualization or immunostaining; the developed HPTLC plate was dipped into 2-propanol-0.2% CaCl2-methanol (40:20:7) for blotting, after which the PVDF membrane and then a glass microfiber filter were placed on the plate and the assemblage was pressed for 30 s with heating (E11). Antiphospholipid antibodies were detected by immunostaining on TLC plates; the method was found to be more specific but less sensitive than ELISA (E12). An improved bioautography agar overlay method was developed for detection of antimicrobial compounds from crude plant extracts using phenol red and a tetrazolium compound as dyes to improve resolution (E13). TLC-fluorescence line-narrowing spectroscopy was used as an offline identification method for narrow-bore column LC (E14). Important factors influencing sensitive and reproducible peroxyoxalate chemiluminescence detection in TLC were found to include synchronization of timing between chemical excitation (spraying of premixed chemiluminescence reagents onto the layer) and subsequent detection of the rapidly changing emission signal by use of a nebulizer to produce a steady stream of reactive aerosol, and an optical fiber to transport the signal to the detector (E15). The quality control of food with near-IR-excited Raman spectroscopy, which eliminates the disturbing fluorescence of impurities caused by visible light excitation, was reviewed (E16). The Hadamard transform technique was extended to include imaging of spots on TLC plates by measuring laser-induced fluorescence and surface-enhanced Raman spectrometry (SERS) with a two-dimensional stationary encoding mask (E17). TLC or HPTLC on layers sprayed with silver colloidal solutions combined with dispersive SERS, laser microprobe SERS, or near-IR-FT-SERS was applied to a variety of compounds of biological, environmental, and surfactant interest (E18). The following studies of TLC or HPTLC combined with IR spectrometry were published: description of TLC using 400 µm × 200 µm × 5 cm (W × D × L) microchannels packed with zirconia stationary phase followed by IR microscopic detection, which improved the minimum detectable quantity of solute by ∼500 times compared to use of microscope slides (E19); use of TLC-IR and TLC-secondary ion mass spectrometry (SIMS) to characterize surfactants (E20); separation of drugs by multicolumn solid-phase extraction (SPE) followed by further separation by TLC and identification by color reagents and online TLC-UV and TLC/FT-IR (E21); TLC-near-IR spectrometry (NIRS) in the diffuse transmittance mode to identify 1 µg levels of solutes on silica gel (E22); and online HPTLC/FT-IR in combination with automated multiple development (AMD) for identification of 30240 ng amounts of hexobarbital, phenobarbital, caffeine, salicyclic acid, and ascorbic acid (E23) and for determination of 10-100 µg/L of EDTA in water (E24). Publications on the combination of TLC with MS were as follow: direct analysis of samples on paper by FABMS (E25); application of 2-D TLC/FABMS to the structure analysis of underivatized phospholipids from the genus Amycolatopsis (E26); direct MS analysis of glycosphingolipid transferred to PVDF membrane by TLC blotting (E27); identification of unlawful food dyes (E28) and tetracycline antibiotics in milk (50 ppb) (E29); HPTLC/liquid secondary-ion MS (LSIMS) of neoglycolipids of glycosaminoglycan disaccharides and of oxymercuration cleavage Analytical Chemistry, Vol. 68, No. 12, June 15, 1996

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products of heparin fragments that contain unsaturated uronic acid (E30); normal-phase HPTLC employing silica, aminopropyl, cyanopropyl, and diol layers for separation of nucleotides and their corresponding bases with off-line FAB and tandem MS (HPTLC/ FABMS/MS) for postchromatographic identification (E31); identification of ecdysteroids in plant and anthropod samples by HPTLC/MS-MS (E32); and silica 60 and C-8 HPTLC/FABMSMS of Pseudomonas rhamnolipids (E33). The application of laser desorption with TLC/MS was reported for peptides using silica gel and cellulose plates and multiphoton time-of-flight (TOF) MS (E34); IR laser desorption of the drug naproxen with two-photon ionization at 266 nm and TOF-MS (E35); and TLC/matrix-assisted laser desorption-ionization (MALDI) of peptides and proteins on silica gel and cellulose plates (E36). Quantitative Analysis. A new, more accurate, and precise internal standard method was introduced, enabling the calculation of the relative response factor of a sample component relative to an internal standard that is independent of the masses of the component and standard within the calibration range; software for the technique is available (F1). A test for the robustness of quantitative OPLC assays, based on a saturated factorial experimental design, was tested for the determination of alkaloids; among the conditions tested, the quality of sorbent alone had a significant influence on the result (F2). The effectiveness of fluorometric scanning using a fiber optic was described in terms of signal-to-noise ratio, accuracy, precision, and detection limit (F3). The use of charge-transfer device (CTD) detectors in planar chromatography and electrophoresis was reviewed (F4). Quantification of cobalt dithizone by TLC was performed with a video hand scanner; a listed short BASIC program converted the scanned picture into chromatographic data (F5). Two-dimensional TLC and fluorescence analysis with a charge-couple device (CCD) video camera can be used to study fluorescent complexes; a particular reported application was the determination of the dissociation of diphenylhexatriene included in β-CD (F6). Image analysis with a CCD camera was used to quantify 2.7-22 mM amounts of phenothiazines separated by TLC and detected by photochemical derivatization (F7). Standards derived from over 30 crude oils were used for calibration of the Iatroscan rod TLC/ flame ionization detector (TLC/FID) technique (F8). Preparative-Layer Chromatography and Radio-Thin-Layer Chromatography. A simple, inexpensive micropreparative TLC system for nanogram to milligram amounts of materials involved removal of thin lines of layer material with a fast-moving drill followed by elution by siphoning eluent through a specially formed sintered glass on one end of the zone or spot and collecting the eluent at the other with a piece of filter paper carton, which is then extracted by soaking and centrifugation (G1). Gradient elution was shown to improve the separation achieved by zonal preparative TLC in ES- and DS-sandwich chambers (G2). Preparative TLC was applied to isolate material in the following studies: photochemical degradation of primaquine antimalarial drug (G3); rapid synthesis of isoprenoid diphosphates (G4); determination of lipid-bound sialic acid in rat brain using preparative TLC and quantitative HPTLC (G5); and isolation of aloine and aloeemodine from Aloe (Liliaceae) (G6). TLC/digital autoradiography was used to quantify testosterone metabolites in the pilosebaceous unit (G7) and in a pilot study of deramciclane anxiolytic compound metabolism (G8). The bioimage analyzer (G9) was applied to TLC studies of the metabolism 6R


of the drug indomethacin (G10) and of pesticides (G11). The use of thin-layer radiochromatography was reported in the following studies: quantification of radiolabeled antibody binding to cells using serum-blocked ITLC strips, on which cell-antibody complexes remain at the origin and unbound antibody migrates with the solvent front (G12); quantification of a 11C-labeled β-adrenoceptor ligand, (S)-(-)CGP 12177, in plasma of humans and rats using straight-phase TLC (G13); determination of radiochemical purity of 99mTc-radiopharmaceuticals available as kits for diagnostic imaging using silica gel or cellulose layers and a linear analyzer (G14, G15); two methods for characterization of [99mTc]bicisate, one for routine quality control of kits and another for quantification of individual radioimpurities (G16); metabolism of the herbicide EPTC by a pure bacterial culture isolated from thiocarbamate-treated soil (G17); assay of liver microsomal dextromethorphan O-demethylation (G18); aerobic degradation of DDT by Alcaligenes eutrophus A5 (G19); 99mTc-labeling of mercaptoacetyltriglycine and related compounds (G20); quantification of type III iodothyronine deiodinase activity using phosphor screen autoradiography (G21); enzymic assay of glycosphingolipid sialyltransferase by RP-TLC (G22); biosynthesis of isoprenoid compounds in Schistosoma mansoni (G23); [32P]DNA labeling and TLC technique to measure DNA environmental biomarkers (G24); and persistence and binding of p,p′-DDE in soil (G25). APPLICATIONS Unless otherwise stated, the references below involved TLC on precoated plates or sheets. TLC plates are rarely hand-coated today, unless a special layer is required that is not available commercially or the cost of precoated plates is prohibitive compared to in-house preparation. Acids and Phenols. Retention behavior was studied for β-CD complexes of phenolic and cinnamic acids by RP-HPTLC with mixtures of buffer solution and methanol, acetonitrile, or THF as mobile phases (H1) and for phenols on silica gel and C-8 and C-18 RP layers (H2, H3). SPE with Amberlite XAD-8 resin was described for cleanup of cassava root polyphenols prior to TLC analysis (H4). Catechins from green tea were separated using RP-TLC with four different solvent systems (H5). An improved cellulose 2-D TLC system was reported for separation of 14 phenolic acids in phytochemical studies (H6). Eighteen reagents were evaluated for detection of aromatic carboxylic acids after TLC on silica gel, polyamide, or silica gel plus Kieselguhr G; bromocresol green, bromothymol blue, sodium hydroxide, thymol blue, and methyl red gave the best results for most compounds, and detection on silica gel layers was better than on polyamide (H7). Polyphenols in ethyl acetate extracts of Platanus acerfolia buds were separated by centrifugal silica gel TLC (H8). NAcylaminonaphthalenesulfonic acid derivatives with potential antihuman immunodeficiency virus activity were analyzed by TLC on type SIII Chromarods and flame ionization detection (H9). The use of scanning densitometry was reported for the following quantitative determinations: -caprolactam, scanned at 200 nm, and -aminocaproic acid, scanned at 588 nm, after derivatization by ninhydrin reagent (H10); phenolic compounds in wine using cleanup on a polyamide column, separation by development with 20% methanol (pH 2.5) on a cellulose plate, visualization with ferric chloride reagent, and scanning at 700 nm (H11); urinary 4-hydroxy-3-methoxymandelic acid by direct urine application and scanning at 560 nm after TLC separation and

postchromatographic derivatization (H12); and sorbic, benzoic, and dehydroacetic acid preservatives in soda, iced tea, and wine by direct spotting on silica gel or C-18 bonded silica gel plates containing fluorescent indicator, development with n-pentyl formate-chloroform-formic acid (2:7:1) and methanol-0.5 M NaCl, respectively, and scanning of fluorescence quenching (H13). The latter method was extended to sample types and concentration levels that could not be analyzed with direct spotting by inclusion of a C-18 SPE extraction and cleanup step (H14). Amino Acids, Peptides, and Proteins. R-Amino acids were separated on tin(IV) selenoarsenate layers with dimethyl sulfoxide (DMSO) mobile phase (I1). Separations of amino acids on silica gel layers impregnated with transition metal ions and their anions were found to be based on the complexing effect between the acids and the metals (I2). Three new solvent systems, pyridinebenzene (2.5:20), methanol-carbon tetrachloride (1:20), and acetone-dichloromethane (0.3:8), provided improved resolution and identification of 18 PTH amino acids compared to previously reported systems (I3). Separations of 18 amino acids were compared on HPTLC silica gel, cellulose, and C-18 bonded silica gel layers, the ability of identify amino acids in the hemolymph and digestive gland-gonad complex of Biomphalaria glabrata snails was studied, and alanine and aspartic acid were quantified in hemolymph by scanning densitometry (I4). A new spray reagent, p-dichlorodicyanobenzoquinone, detected amino acids with 0.1-1 µg detection limits and produced various distinguishable colors that facilitate identification (I5). A new topological index was developed for predicting the separation of D and L optical isomers of amino acids and hydroxy acids on a chiral stationary phase (I6). TLC on Chiralplates with acetonitrile-methanol-water (4:1:1) mobile phase and ninhydrin detection reagent was used in the quality control of L-tryptophan (I7), and thyroxine enantiomers were separated by chiral TLC to determine optical purity in bulk materials (I8). Amino acid racemates were separated on silica plates impregnated with a complex of copper and L-proline (I9) and on borate-gelled guranimpregnated silica gel (I10). RP-TLC separations of dansyl amino acid enantiomers were carried out by use of β-CD mobile-phase additive (I11), while 2-O-((R)-2-hydroxypropyl)-β-cyclodextrin mobile-phase additive gave improved chiral recognition compared to β-CD for enantiomers of six amino acids (I12). Dried blood spots from patients with homocystinuria were analyzed for homocysteine by cellulose TLC (I13), while spots on Guthrie cards were directly transferred to TLC plates for neonatal screening for amino acid disorders (I14). Densitometry was used for validation of quantitative amino acid analysis on mixed natural zeolite-microcrystalline cellulose layers (I15); quantification of L-lysine, L-threonine, L-homoserine, and cobalamins in fermentation broths (I16); and quantification of amino acids in protein extracted from cane sugar after hydrolysis, derivatization with dansyl chloride, and silica gel HPTLC with 5% EDTA-butanol-diethyl ether (5:10:35) mobile phase (I17). The use of Serva Blue W stain combined with TLC proved to be a simple and effective procedure for visualization of cyclic peptides in studies of the stability of peptide inhibitors toward proteolytic degradation (I18). Techniques for phosphopeptide mapping and phosphoamino acid analysis on cellulose layers were reviewed (I19). TLC on a silica plate with propanol-water (2.1: 1) mobile phase was suitable to determine phosphotyrosine from

tyrosine-phosphorylated protein without interference by contaminants from hydrozylates (I20). Antibiotics. A TLC bioautography method was reported for the simultaneous semiquantitative determination of the polyether antibiotics monensin, salinomycin, narasin, and lasalocid in poultry meat in which two successive developments provided cleanup of sample extracts and separation of the antibiotics (J1). Purity control of six tetracyclines was carried out by semiquantitative TLC on silica gel plates sprayed with EDTA and adjusted to pH 8-9, development with dichloromethane-methanol-water mobile phases, and inspection of fluorescence under 365 nm UV light (J2). A silica gel TLC method with methanol-20% NaCl solution (15:85) mobile phase and fluorescence detection after derivatization with 4-chloro-7-(nitrobenzo)-2-oxa-1,3-diazole that was developed to determine the relative amounts of the B and C components of commercial neomycin sulfate was found to be much easier to perform than the official method based on ion exchange chromatography and ninhydrin colorimetric detection (J3). Densitometric methods on silica gel plates were reported for the following antibiotics analyses: assay and purity control of minocycline on an EDTA-impregnated layer with dichloromethanemethanol-water (57:35:8) mobile phase and UV and fluorescence densitometry (J4); neomycins A, B, and C using methanol-25% ammonia solution-acetone-chloroform (35:20:20:5) mobile phase, fluorescamine detection reagent, and fluorescence scanning at 302 nm/>400 (cutoff filter) wavelengths (J5); oxolinic acid, erythromycin, and oxytetracycline in fish feed using untreated or impregnated layers and fluorescence or visible absorption densitometry (J6); macrolide antibiotics in chicken meat by extraction with acetonitrile-4% aqueous KCl (9:1), defatting with hexane, reextraction with chloroform-ethyl acetate (2:1), cleanup and separation by double development, and quantification at 302 nm without derivatization (erythromycin) or at 517 nm after detection by 4-methoxybenzaldehyde (tylosin) (J7); 5-(hydroxymethyl)-2furfural in dextrose-containing antibiotic parenteral solutions (J8). Bases and Amines. Chromatographic behavior studies were carried out for aromatic amines on plain and mixed adsorbent layers (K1), aromatic amines on silica gel impregnated with aqueous salt solutions (K2), and sulfonamides on normal and reversed phases in order to determine hydrophobicity parameters (K3). Computer-aided optimization of a sample cleanup procedure was applied to the TLC analysis of amines and nitrosamines (K4). Fourteen chiral amino alcohols and amines were resolved by development with methanol-water mobile phases on C-18 RP layers after derivatization with Marfey’s reagent (K5). Thirteen aromatic amines were separated by TLC using surfactants as mobile or stationary phases; the best separation was achieved when sodium dodecyl sulfate was used (K6). Catecholamines were determined in human urine by separation on amino-modified silica gel layers followed by in situ visualization through heating the plate; thermal visualization was also applicable to other urine components such as creatine, creatinine, uric acid, and glucose (K7). Nanogram levels of brain catecholamines and 5-hydroxytryptamine were acetylated, resolved on silica gel HPTLC plates, and quantified by fluorescence densitometry at 415 nm excitation wavelength (K8). Biogenic amines in fish (K9) and other foods (K10) were determined using 2-D separation on silica gel with benzene-triethylamine-acetone (10:2:1) and benzene-triethylamine (5:1) mobile phases, detection with dansyl chloride reagent, and spectrofluorometry (K11). Analytical Chemistry, Vol. 68, No. 12, June 15, 1996

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Carbohydrates. The retention properties of R-, β-, and γ-cyclodextrins were examined using water-wettable RP-C-18 layers and mobile phases composed of acetonitrile, THF, methanol, ethanol, or propanol with water or methanol in acetonitrile (L1). The retention of aromatic N-glycosides was studied using overpressured development on silica gel layers impregnated with tricaprylmethylammonium chloride and methanol-water mobile phases (L2). Hydrolysis with trifluoroacetic acid and silica gel TLC with 1-propanol-water-ammonia (79:20:1) mobile phase and p-anisaldehyde phthalate detection reagent were used to determine eight sugars of plant gums for the identification of the gums in art objects (L3). The glycosyl sequence of glycosides was determined by enzymatic hydrolysis followed by separation of the hydrolyzate by TLC and direct analysis of the spots by FABMS (L4). The determination of sugars in food or clinical samples without cleanup procedures was performed by AMD with a polarity gradient based on acetonitrile-acetone-water on buffered amino layers and scanning densitometry for quantification (L5). Nanogram amounts of maltodextrins and isomaltodextrins containing 1-20 glucose units were determined by TLC-densitometry with R-naphthol-sulfuric acid detection reagent (L6). A densitometric method using preadsorbent HPTLC silica gel 60 plates impregnated with sodium bisulfite and pH 4.8 citrate buffer, triple development with acetonitrile-water (85:15), and zone detection with R-naphthol reagent was described for the determination of sugars in the hemolymph and digestive gland-gonad complex of infected B. glabrata (L7) and Helisoma trivolvis (L8) snails. N-Acetylchitooligosaccharides were analyzed by use of the Iatroscan TLC/FID system (L9). Dyes and Pigments. Simple qualitative TLC and quantitative spectrophotometric methods were developed for dyes such as Solvent Red 164 and Solvent Blue 98 in diesel fuel to meet Internal Revenue Service regulations (M1). Silica gel and RP-TLC and HPTLC methods were devised for analysis of commercial semipermanent hair dyes (M2) and triphenylmethane dyes used in cytological and histological techniques (M3). Permitted and prohibited synthetic colors in beverage alcohol products at subppm levels were reliably identified by SPE on an amino-bonded silica column and silica gel TLC with two complementary solvent systems (M4). Two-dimensional cellulose TLC methods were described for identification of seven permitted dyes used in foods and pharmaceutical preparations in Egypt (M5). A three-step TLC procedure was used to examine the colored components of printing and writing inks and other marking materials (M6). Densitometric silica gel TLC or HPTLC was used in the following determinations: forensic analysis of inks, with comparison to microspectrophotometry (M7); 12 yellow direct azo industrial dyes developed with pyridine-35% ammonia-2-butanol (1:1:3) (M8); quantification of erythrosine in hard gelatin capsules using extraction and cleanup on a polyamide filter column eluted with ammoniacal methanol (M9); quantification of dyes in hair color products (M10); identification of inks from typed script of electronic typewriters using Rf values and in situ visible spectra (M11); and dating ballpoint pen inks by TLC separation and densitometric evaluation of chromatograms using a new massindependent technique that is also effective for comparative examination of other forensic samples such as colored paints and fibers (M12). Procedures and materials for the TLC determination of carotenoids in biological extracts were reviewed (M13). A simple 8R


technique for determination of free porphyrins in urine or feces for diagnosis of porphyria was based on C-18 HPTLC with detection of fluorescent zones under long-wavelength UV light (M14). Various plain, mixed, impregnated, and bonded layers were tested for their ability to separate the color pigments of paprika, and the best systems were aluminum oxide developed with hexane-chloroform mixtures (adsorption) and impregnated diatomaceous earth developed with eluents comprising mixtures of THF, acetone, and water or acetone and water (reversed phase) (M15). The separation and simultaneous determination of β-carotene, cantaxanthin, lutein, violaxanthin, and neoxanthin was accomplished using rod TLC/FID and a two-stage development technique; quantitative results were excellent, and 10 samples could be analyzed in less than 2 h (M16). cis- and trans-Carotenes of tangerine and yellowish tangerine tomatoes were determined by TLC on a mixed magnesia-alumina-cellulose-calcium sulfate (10:6:2:2) layer with stepwise gradient development from hexane2-propanol-methanol (100:2:0.2) to pure hexane and scanning densitometry for quantification (M17). The following TLC studies of flavonoids and flavanones were published: polyamide TLC separation of flavanones from traces of other types of flavonoid compounds with crystallization of the flavonoid compounds before and after chromatography (M18); determination of the hydrophobic parameters of flavonoids by RPTLC (M19); determination of ipriflavone and its impurities by TLC with absorbance, fluorescence, and fluorescence quenching detection at 1 ng levels (M20); efficient separations of polyhydroxyand polymethoxyflavones on silica gel developed with heptane2-propanol (80:20) + 5% acetic acid and on C-18 layers developed with methanol-water (80:20 or 75:25) + 3% NaCl (M21); quantitative TLC of iridoid and flavonoid glucosides in Linaria species (M22); and flavonoid quantification in rutin-containing buckwheat herb extract by silica gel TLC with scanning densitometry (M23). Hydrocarbons. TLC and HPTLC methods for the separation and identification of some nitrogen derivatives of polycyclic aromatic hydrocarbons (PAHs) in airborne particulate matter (N1) and for separation and quantification of PAHs in water (N2) with fluorometric detection were described. A quick, inexpensive qualitative forensic analysis was developed for residues from petroleum products generally encountered in arson cases based on ethyl ether extraction of samples, silica gel TLC with heptane or isooctane mobile phase, and application of several sensitive and selective detection methods (N3). Kerosine as an adulterating fluid in gasoline was semiquantified by silica gel TLC with heptane mobile phase and UV visualization of zones (N4). Soil extracts were analyzed for PAHs by RP-TLC (N5). TLC/FID is primarily used for hydrocarbon and lipid analysis. Analyses based on TLC/FID were developed for evaluation of the hydrocarbon oil-degrading capability of marine organisms (N6, N7), quantitative evaluation of bitumin composition (N8, N9), and quantitative hydrocarbon group-type analyses of petroleum hydroconversion products (N10). Lipids. Lipids are among the most widely analyzed compounds by TLC because of several important inherent advantages. In HPLC analysis, many lipids lack chromophores that facilitate UV-vis detection and the wide polarity and solubility range of various lipid classes makes isocratic analysis impossible, while most GC analyses require prior derivatization of lipids. In TLC analysis, many good lipid detection reagents are available, and layers can be impregnated with various reagents to improve

selectivity, such as silver nitrate (argentation TLC) to fractionate lipid mixtures on the basis of the number, configuration, and position of double bonds in their components. Two-dimensional TLC allows application of two separation mechanisms in succession, e.g., adsorption and argentation chromatography on a silica gel plate partly impregnated with silver nitrate. A special issue of the Journal of Chromatography, B (Biomedical Applications) (1995, 671 (1, 2)) included a general review of TLC by J. C. Touchstone, one of the pioneers in modern quantitative TLC, in addition to reviews of silver ion chromatography, analysis of lipid oxidation products, inositol phospholipids, bile acids, and cholesterol and related lipids, all of which contained information on procedures and applications of TLC. New visualizing reagents reported for fatty acid derivatives (O1), bile acids (O2), and cholesterol (O3) on silica gel and aluminum oxide comprised a number of acid-base indicator dyes such as bromothymol blue, bromophenol blue, and aniline blue. Dolichol and dehydrodolichol were separated from each other with concomitant separation of each family with respect to carbon chain length by successive development on silica gel and RP plates (O4). All stratum corneum lipids were separated by AMD on HPTLC silica gel plates using an initial isocratic step followed by a 25step gradient from methanol-water to hexane (O5). Bakers’ yeast was analyzed for lipids using silica gel with hexane-diethyl etheracetic acid (70:30:1) for class separation and by a two-step process using silica gel with acetone and with chloroform-methanolacetic acid-water (25:15:4:2) for phospholipids (O6). Argentation TLC was used for the following separations: positional isomers of monosaturated fatty acids as their phenacyl derivatives (O7); polyunsaturated fatty acids with detection by selective self-staining after development with toluene-acetone mixtures (O8); positionally isomeric triacylglycerols on silica gel impregnated with low concentrations of silver ion and development with chloroform-methanol in open cylindrical tanks (O9); and molecular species of triacylglycerols from highly unsaturated plant oils by successive argentation and RP-TLC (O10). TLC combined with immunostaining was used to analyze glycolipids and mycolic acids from Mycobacterium strains and related taxa (O11). TLC analysis of glycosphingolipids was reviewed (O12), and the following glycosphingolipid (GSL) TLC studies were published: detection at the 5 pmol level using 5-hydroxy-1-tetralone as fluorescent labeling reagent (O13); TLC and TLC-immunostaining analysis of neutral and sulfated glucuronyl GSLs purified from human motor and sensory nerves and myelins (O14); and purification of GSLs and phospholipids by the TLC blotting technique (O15). Improved HPTLC separation of gangliosides was obtained by utilizing AMD (O16), and ganglioside detection was simplified and made more sensitive by use of chemiluminescence (O17). The extraction, purification, separation, and quantitative analysis of membrane phospholipids by TLC was reviewed (O18). The following phospholipid TLC studies were reported: comparison of mobile phases and HPTLC qualitative and quantitative analysis, on preadsorbent silica gel plates, of phospholipids in B. glabrata snails infected with Echinostoma caproni (O19); separation of phospholipid classes by OPLC (O20); and TLC determination of phosphotidylcholine for liposome characterization using silica gel 60 layers and n-butanol-n-propanol-water mobile phase (O21). Densitometric quantification was applied to the following lipid determinations, carried out by single development, one-dimen-

sional (1-D) TLC or HPTLC on unmodified silica gel layers unless otherwise noted: dipalmitoylphosphatidylcholine in amniotic fluid as free dipalmitoylglycerol on silver nitrate-modified silica gel HPTLC plates after enzymic hydrolysis (O22); human stratum corneum lipids by sequential 1-D TLC with detection by charring (O23); four phospholipids for identification of fetal lung maturity with chloroform-methanol-ethanol-acetic acid-water (24:4:2: 6:0.5) mobile phase, detection by exposure to iodine vapor, and scanning at 460 nm (O24); gangliosides by use of 2-D HPTLC, resorcinol detection reagent, and computer-assisted image analysis densitometry (O25); natural galactolipids of oat and wheat origin with 8-anilino-1-naphthalenesulfonate (ANS) as fluorogenic visualization reagent and scanning at an excitation wavelength of 376 nm (O26); neutral lipids in regular and low-fat eggs using chloroform-methanol (2:1) microextraction, separation of lipids in extracts by development with the Mangold solvent system or a modified system for cholesterol esters, detection by spraying with phosphomolybdic acid (PMA), and reflectance scanning at 700 nm (O27); and phospholipids using molybdate detection reagent and a personal computer-assisted desk-top scanner that was much less expensive than conventional densitometers (O28). Lipid analysis using the silica gel-coated quartz rod TLC/FID technique was reviewed (O29). TLC/FID was used to quantitatively analyze lipids from cooked beef (O30); cereal lipids (O31); lipid class compositions of adult Pacific oysters to examine the effect of lyophilization on solvent extraction (O32); phospholipids from marine bacteria (O33); and linoleyl derivatives to evaluate susceptibility to oxidation (O34). Pesticides. Advances in the procedures and applications of TLC and HPTLC for the separation, detection, and qualitative and quantitative determination of pesticides and related compounds were reviewed for the past several years, including insecticides, herbicides, and fungicides belonging to different chemical classes; the use of radio-TLC for pesticide metabolism, uptake, and degradation studies was also covered (P1). A computer-assisted statistical scanning method written in HP BASIC 4 was developed for mobile-phase optimization in the 2-D TLC separation of eight pesticides (P2). Modification of the hydrophobicity of 28 pesticides with a water-soluble β-CD polymer in the presence of aqueous NaCl was studied by RP-TLC (P3). The successful transfer of chromatographic conditions from TLC to HPLC columns was demonstrated for 62 pesticides on C-18-, C-8-, diol-, amino-, and cyano-bonded silica gel stationary phases (P4). The following studies related to the AMD-TLC determination of pesticide multiresidues in water were described: factors influencing sample preparation by C-18 SPE (P5); coupling with MS and comparison to other screening methods (P6); and application to the detection of 283 pesticides using in situ reflectance spectra and a software program to facilitate pesticide recognition (P7, P8). Dichlorvos and dimethoate were detected at 1-15 µg/spot levels by reaction of the alkali hydrolysis product of each pesticide with orcinol to produce a yellow fluorescent product (P9). Carbaryl and propoxur were detected in water and grain samples using a method based on detection with diazotized p-nitroaniline and 6-amino-1-naphthol-3-sulfonic acid (J-acid) (P10). Organotin residues in vegetables, fruits, and tap water were analyzed to determine compliance with Swiss legislation by use of atomic absorption spectrometry (AAS) and TLC (P11). Monocrotophos was determined in biological materials by use of alkaline hydrolysis to yield N-methylacetoacetamide, which was reacted Analytical Chemistry, Vol. 68, No. 12, June 15, 1996

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with diazotized sulfanilamide or sulfanilic acid to give a red color; the detection limit was 1 µg, and other organophosphorus (OP), organochlorine, and pyrethroid pesticides or coextracted constituents of viscera did not interfere (P12). Different methods for the separation, activation, and quantification of OP insecticides using TLC with enzyme inhibition were examined, with special attention to activation with bromine, hypochloric acid, and mchloroperbenzoic acid (P13). Radio-TLC was used to measure the chemical and biological release of 14C-bound residues from soil treated with [14C]-p,p′-DDT (P14) and microsomal oxidation of the herbicides EPTC and acetochlor and of the safener MG191 in maize (P15). The following TLC/densitometry pesticide analyses were reported: thiram, thiophanate-methyl, and 3-indolebutyric acid in acrylic antifungal formulations using liquid-liquid and solidliquid extraction, silica gel TLC with hexane-ethyl acetateacetone (4:4:1) mobile phase, and scanning at 254 nm with use of an internal standard (P16); metribuzin and its major metabolites in soil and water by C-18 SPE, RP-TLC, and scanning at 290 nm (P17); atrazine and simazine in drinking and surface water by C-18 SPE, silica gel HPTLC with nitromethane-tetrachloromethane (1: 1) mobile phase, and UV scanning (P18); and pentachlorophenol and cymiazole in water and honey by C-18 SPE, separation on a silica gel HPTLC-F layer, and scanning of fluorescence quenching (P19). Pharmaceuticals, Drugs, and Alkaloids. The retention behavior of barbiturates by OPLC on silica gel layers impregnated with dodecyltrimethylammonium bromide or paraffin and developed with mixtures of methanol and water was studied (Q1). The enantiomers of the β-blocking drugs metoprolol, propranolol, and, alprenolol were separated on diol layers with dichloromethane and a chiral counterion, N-benzoylcarbonylglycyl-L-proline, as mobile-phase additive (Q2). The separation of 15 alkaloids was studied on unmodified silica gel and in RP ion association systems (Q3). Diazonium salts were evaluated as visualization reagents for amphetamines (50 ng sensitivity) (Q4), and diazotization and coupling with the Greiss reagent after hydrolysis, reduction with stannous chloride, and addition of ammonium chloride for benzodiazepines (100 ng) (Q5). TLC screening and GC/MS confirmation techniques for drugs of abuse were reviewed (Q6), and TLC screening procedures were compared favorably with immunochemical tests (Q7). The following TLC urine drug screening studies were described: use of the Toxi-Lab system, with one method for base and neutral drugs and another for acid and neutral drugs (Q8); impact of hot and humid tropical conditions on results with the Toxi-Lab systems (Q9, Q10); flunitrazepam and its metabolites via acridene derivatives with fluorescence detection (Q11); interferences of adulterants on TLC screening of morphine, diazepam, and phenobarbital (morphine was found to be most sensitive to all adulterants, and adulterants interfered at lower concentration for TLC compared to EMIT techniques) (Q12); and facilitation of identification of opiates by derivatization with acetic anhydride or methoxyamine (Q13). A method for rapidly screening pharmaceuticals, designed for operators with limited resources and training, was based on performing TLC in a plastic bag under reproducible conditions; the analysis can be performed without electricity or in remote areas away from the laboratory (Q14). An on-site testing method for sulfamethazine in pork carcasses at 100 ppb was developed 10R


for use by the pork industry based on minicolumn preconcentration and TLC detection (Q15). Commercial silica gel 60-F254 plates and new mobile phases were incorporated in methods contained in the German pharmacopeia (Q16). Pyrrolizidine alkaloids were detected in borage seed oil on silica gel plates developed with dichloromethanemethanol-25% aqueous ammonia solution (79:20:1) with detection by Mattock, Dragendorff, and iodoplatinate reagents (Q17). Principal components analysis of standardized Rf values of 443 drugs and metabolites chromatographed in four TLC sheet systems allowed simple, inexpensive, and fast identification of unknown drugs in blood and urine samples (Q18). A new TLC method for detecting 5 µg amounts of cocaethylene and cocaine involved SPE of urine buffered to pH 9.3, silica gel TLC with hexane-toluene-diethylamine (13:4:1) mobile phase, and iodoplatinate spray reagent (Q19). Chemical tests and TLC information for rapid identification of 87 colored, bioconvex, unscored tablets and drage´es registered in Austria were tabulated (Q20). SPE on a copolymeric cation exchange column and silica gel TLC with acetone-ethanol-ammonia mobile phase and fluorescamine detection reagent were used to detect hygromycin B in bovine plasma and swine urine at 50 ppb (Q21). Asprindine and nadoxolol were detected in human plasma at 100 and 300 ng levels, respectively, by C-18 SPE and ascending or horizontal sandwichchamber silica gel TLC with diethyl ether-methanol (7:3) and ethyl acetate-concentrated ammonia (8:2) mobile phases and detection with Kiefer reagent (Q22). Benzodiazepines and zopiclone were detected in serum at 0.1-0.4 µg/mL by HPTLC Rf values and spot colors in three systems (Q23). To identify counterfeit pharmaceutical products, fast TLC methods were described for testing and quality control of nine drugs, six of which are included in the Essential Drug List (Q24). Fifteen alkaloids were purified by TLC decomposition of their picrates using silica gel and alumina as adsorbents; identification was based on melting points and UV-vis spectra (Q25). Ivermectin was determined in cattle serum at 0.1 ng by TLC after derivatization with trifluoroacetic anhydride-1-methylimidazole and visual examination of fluorescence under long-wavelength UV light (Q26). An HPTLC fingerprint technique and bioassay were used to establish the shelf-life of a proprietary herbal formulations (Q27). The content of active ingredient in nifedipine preparations in terms of USP XXI requirements was evaluated by TLC/UV and GC/ MS methods (Q28). Quantification of oxyphenbutazone and ibuprofen in the presence of paracetamol and dextropropoxyphene in pharmaceuticals involved separation by TLC, scraping and extraction of the components with methanol, and UV spectrophotometry (Q29). Elemental sulfur in complex sulfur ointments was rapidly estimated by separation on silica gel with petroleum ether mobile phase, scraping and chloroform elution of the sulfur band, and measurement of absorbance at 265 nm (Q30). Furazolidone and metronidazole were simultaneously quantified by silica gel HPTLC with toluene-ethyl acetate-methanol (6.5:3.5:0.5) mobile phase and diloxanide furoate internal standard (Q31). The following compounds were quantified by TLC or HPTLC (on silica gel layers unless otherwise noted) by use of absorption or fluorescence scanning densitometry: rifampicin in drug excipient interaction studies with chloroform-methanol-water (80: 20:2.5) mobile phase (Q32); metoclopramide and paracetamol in their combined dosage form with ethyl acetate-acetone-ammonia (60:40:1) mobile phase and scanning at 300 nm (Q33);

amitriptyline and chlordiazepoxide in combined dosage forms using ethyl acetate-methanol-diethylamine (9.5:0.5:0.05) mobile phase and scanning at 245 nm (Q34); phenytoin in pharmaceutical formulations and identification of its hydroxylated urinary metabolite (Q35); cannabinoids in plasma by C-18 SPE, derivatization with dansyl chloride, and scanning at 340 nm (Q36); amiloride hydrochloride and frusemide in pharmaceutical preparations with ethyl acetate-methanol-18% ammonia (7.5:1:0.8) mobile phase, hydrochlorothiazide internal standard, and scanning at 275 nm (Q37); (15S)-15-methylprostaglandin F 2-R methyl ester (Carboprost Methyl) in the veterinary pharmaceutical formulation Plexaprost by use of dichloromethane-acetone (3:1-1:1) mobile phase, detection with PMA, and scanning at 750 nm (Q38); halofantrine in biological samples by C-8 SPE, hexane-ethanoltriethylamine (92.5:2.5:5) mobile phase, and scanning at 256 nm (Q39); amlodipine besylate in tablets with chloroform-acetic acid-toluene-methanol (8:1:1:1) mobile phase and scanning of fluorescence at 366 nm (Q40); buprenorphine hydrochloride in pharmaceuticals (Q41); chloramphenicol monosuccinate and gentamicin as examples of the use of quantitative TLC for quality control of drugs stored long-term by the German Federal Armed Forces Medical Service (Q42); nortryptyline and fluphenazine in combination in tablets (Q43); ticlopidine in dosage forms with butanol-acetic acid-water (4:1:5) mobile phase and UV scanning or visible scanning after spraying the layer with ninhydrin (Q44); FCE 23762 (methoxymorpholinodoxorubicin hydrochloride), a new antitumor agent, with chloroform-methanol-acetic acid (93: 6:1) mobile phase and UV or fluorescence scanning (Q45); chlorambucil and its decomposition product with chloroformmethanol (17:3) mobile phase (Q46); retinoids complexed to cyclodextrin based on measurement of fluorescence with a CCD camera (Q47); Praziquantel and avermectins in Pramex tablets using chloroform-ethyl acetate-methanol-dichloromethane (9: 9:1:2) mobile phase and dual-wavelength scanning at 260 nm/ 340 nm and 240 nm/340 nm, respectively (Q48); mixtures of carbadox, nitrofurazone, nitrofurantoin, furazolidone, and furaltadone (Q49); erythromycin in commercial bulk and biological samples by use of dichloromethane-methanol-25% ammonia (90:9:1.5) mobile phase, xanthydrol detection reagent, and scanning at 525 nm (Q50); aloin in laxatives with a horizontal chamber (Q51); escin in horse chestnut extracts (HPLC and densitometric TLC gave accurate and reproducible results in excellent agreement) (Q52); lovastatin lactone and free hydroxy acid from fermentation broths with dichloromethane-acetic acid (85:15) mobile phase and scanning at 233 nm (Q53); sulfonamide residues in eggs using dichloromethane-acetone (1:1) extraction, column chromatography cleanup, and fluorescamine detection (Q54); prednisolone in preparations and aqueous humor from rabbits’ eyes by stepwise-gradient TLC (results were comparable to those from HPLC and radioisotope methods) (Q55); elemental sulfur in topical skin medications by fluorescence quenching densitometry (Q56); clobetasol propionate in topical creams (Q57); quaternary ammonium antiseptics on silanized silica gel with methanol-25% sodium acetate-acetone (65:35:20) mobile phase, potassium triiodide detection reagent, and scanning at 400 nm (Q58); digoxin, digoxigenin, bisdigitoxoside, and gitoxin in digoxin drug substance and tablets on a C-18 plate using watermethanol-ethyl acetate (25:24:1) mobile phase and absorbance and fluorescence scanning (Q59); omeprazole in bulk and dosage forms with methanol-water (2:1) mobile phase and scanning at

302 nm (Q60); 1,8-cineole in Eucalyptus essential oils with petroleum ether-chloroform (7:3) mobile phase, 4-(dimethylamino)benzaldehyde-sulfuric acid chromogenic detection reagent, and scanning at 460 nm (results were equivalent to those using a GC method) (Q61); ketotifen fumarate in bulk and pharmaceuticals using ethyl acetate-methanol-ammonia (15:1.5:0.1) mobile phase and scanning at 301 nm (Q62); nitrendipine and nimodipine in pharmaceutical dosages with toluene-ethyl acetate (1:1) mobile phase and scanning at 236 and 240 nm, respectively (Q63); propranolol hydrochloride and hydrochlorothiazide in tablets with benzene-methanol-ethyl acetate-ammonia (8:2:1:0.2) mobile phase and scanning at 280 nm (Q64); theophylline and etofylline in dosage forms using chloroform-methanol (9:1) mobile phase and scanning at 278 nm (Q65); paracetamol and diclofenac in pharmaceutical preparations with chloroform-methanol-ammonia (10:2.5:0.1) mobile phase and scanning at 286 nm (Q66); ibuprofen and paracetamol in combined dosage formulation using hexane-ethyl acetate-acetic acid (90:25:10) mobile phase and scanning at 265 nm (Q67); furazolidone and metronidazole in combined dosage form (Q68); benzoyl peroxide in acne medications by fluorescence quenching densitometry (Q69); chloroprocaine and its major impurity, 4-amino-2-chlorobenzoic acid, in drug substance and injection dosage form (Q70); p-aminosalicylic acid and its major impurity, m-aminophenol, in bulk and pharmaceuticals with chloroform-ethyl acetate-acetic acid-methanol (46:29:21:4) mobile phase (Q71); the indole alkaloids catharanthine and vindoline in Catharanthus roseus by scanning at 280 and 310 nm, respectively, after separation by triple development with petroleum ether-diethyl ether-acetone-ethanol (70:10:20:1) (Q72); ciprofloxacin and degradation products during UV photodegradation studies in aqueous solution using acetonitrileammonium chloride buffer (pH 10.6-11.1) eluents (Q73); drugs in equine urine samples (TLC was compared favorably to HPLC) (Q74); tinidazole and furazolidone in suspensions with chloroformmethanol-ammonia (9:1:0.1) mobile phase and scanning at 335 nm (Q75); antihistamines in multicomponent formulations (Q76); and solanum glycoalkaloids in potato leaves and tubers by a method designed for use in potato breeding programs based on microscale extraction, a simple cleanup procedure, and TLC scanning (Q77). Although all of the papers on densitometric TLC cited above contained some validation, such as determination of linear calibration range, limit of detection, limit of quantification, accuracy (recovery), precision (relative standard deviation), and/or ruggedness (interlaboratory study), five papers were devoted specifically to the topic of method validation, including general aspects of experimental design and statistical tests (Q78-Q80), a comparison of parameters in TLC and OPLC (Q81), and ruggedness testing (Q82). Ajmaline stereoisomers were determined by combined HPLC/ TLC; TLC discriminated ajmaline, isoajmaline, and sandwicine or isosandwicine, whereas HPLC separated every pair of the alkaloids except for the normal series of bases (ajmaline-sandwicine) (Q83). Alkaloids derived from Sanguinaria canadensis were separated by one- and two-dimensional TLC and capillary zone electrophoresis (CZE) and identified by TLC/FABMS; the higher loadings possible for TLC allowed easier identification of mixture components compared to CZE, and reproducibility of Rf and mass spectral data was excellent (Q84). Analytical Chemistry, Vol. 68, No. 12, June 15, 1996

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Purines, Pyrimidines, and Nucleic Acids. Reference maps of mobilities of modified ribonucleotides and nucleosides separated by 2-D cellulose TLC were presented (R1). Mixtures of purines and pyrimidines were separated on layers of the zeolite heulandite used as an adsorbent (R2). Comparison of TLC- and HPLC-32P-postlabeling assay for cisplatin-DNA adducts showed that one of the standards, platinated d(TGG), could be analyzed with recovery of 31% for both methods when the amount of adduct was 0.5-100 fmol, while for platinated DNA TLC had measurement sensitivity of 3.2 fmol and recovery of 28% compared to respective values of 8-40 fmol and 16% for HPLC (R3). Cigarette smoke-induced DNA adducts in human lymphocytes and granulocytes were analyzed by butanol extraction and nuclease P1enhanced 32P-postlabeling and thin-layer radiochromatography (R4). Multidimensional TLC was coupled with accelerator MS to study DNA adduction with heterocyclic amines (R5). Steroids. The influence of temperature, ionic strength, mobile-phase pH, and addition of modifiers to the mobile phase or support on the silica gel TLC of bile acids was evaluated (S1). Heulandite layers developed with carbon disulfide-pyridine (1: 1) were effective for the separation of steroid hormones (S2). A reversed-phase ion-pair OPLC method was optimized and validated for purity testing of the diuretic steroid potassium canrenoate (S3). A sensitive, reliable, and rapid silica gel TLC method was devised for the separation, identification, and quantification of regioselective and stereospecific androgen metabolites (S4). HPTLC and GC/MS were applied to the detection of anabolic steroids used as growth promoters in illegal cattle fattening within the European Community (S5). Corticosteroid hormones available on the European market were identified by silica gel TLC with a variety of mobile phases and fluorescence detection by spraying with alcoholic sulfuric acid and heating (S6). Corticosteroids and their esters in pharmaceutical preparations of creams and ointments were identified and quantified by dissolving in chloroform, centrifugation to remove water and insoluble material, silica gel TLC with hexane mobile phase to wash out base ingredients followed by chloroform-ethyl acetate (1:1) for free steroids or (2:1) for esters, and spectrodensitometry at 240 nm; recoveries were 98-101%, and excellent agreement of results with official methods was obtained (S7). Surfactants. The analysis of cationic surfactants by TLC, GC, and HPLC was reviewed (T1). The lipophilicity and specific hydrophobic surface area of 22 nonhomologous nonionic surfactants were determined by RP-TLC using methanol as an organic modifier (T2). Various mixtures of 16 anionic, cationic, amphoteric, and nonionic surfactants were separated by multiple development on silica gel plates (T3). RP-HPTLC combined with sample cleanup by ion exchange chromatography was used to quantify alkylphenolethoxylates in detergents and cleaning agents (T4). RP-TLC on C-18 bonded silica gel layers was used for the determination of the chain length distribution of alkylpolyglucoside surfactants (T5). Two-dimensional TLC with scanning densitometry allowed quantitative determination of ethylene oxide oligomer distribution in ethoxylated alkylphenol carboxymethyl ether salts; the surfactant’s degree of conversion, average ethoxylate number, and distribution were simultaneously determined on a single plate (T6). Toxins. The use of HPTLC for cost-effective, rapid, and reproducible quantification of aflatoxins in foods at picogram levels was reviewed (U1). A comparison of the reliability of mycotoxin 12R


assays found that the precision of TLC and HPLC is about the same, but that of ELISA is somewhat poorer (U2). A solventefficient TLC method using either visual or densitometric techniques for determining aflatoxins B1, B2, G1, and G2 in corn and peanut products was collaboratively studied and adopted as a first action official method by AOAC International (U3). The occurrence of aflatoxin M1 in 100 milk samples at 0.01-0.04 µg/L was determined by a dialysis diphasic procedure and HPTLC (U4). The efficiencies of two different immunoaffinity columns and a phenyl-bonded column were compared for the extraction and cleanup of aflatoxin B1 from sorghum and corn during its determination by fluorodensitometry (U5). Fumonisin B1 in corn was determined with 2-10% RSD and 100 mg/kg quantification limit by SPE, two-step TLC, and densitometry after derivatization with p-anisaldehyde (U6). TLC and competitive immunoassay methods were compared for detecting fumonisin on corn, and both methods were found to be well suited for rapid screening of contamination (U7). The use of liquid-liquid extraction and TLC gave a recovery rate of 92.5% for determination of ochratoxin A in blood serum of pigs at picogram per milligram levels (U8). Deoxynivalenol was determined in wheat with a detection limit of 40 ng/g by a modified HPTLC method involving extraction with acetonitrile-water (84: 16), cleanup on a charcoal-alumina-Celite (7:5:3) column, silica gel HPTLC with chloroform-acetone-2-propanol (8:1:1) mobile phase, spraying with aluminum chloride detection reagent, and fluorodensitometry (U9). Cyanobacterial hepatotoxins were detected in aqueous and algal samples by a TLC method utilizing in situ spectrum measurement (U10). Vitamins. Various dyes were evaluated as detection reagents for vitamins D, A, and E after separation by adsorption and partition TLC (V1). Separation of tocopherol isomers and enantiomers and the relationship between Rf values and topological indexes were studied (V2). TLC, HPTLC, and HPLC methods were developed for identification of retinoic acids, retinol, and retinyl acetate in topical facial creams and solutions (V3). Vitamin B complex and folic acid were separated on silica gel layers impregnated with transition metal ions and detected by exposure of the layer to iodine vapor (V4). Vitamin K was assayed in bovine liver by use of RP-TLC separation with dichloromethanemethanol (7:3) mobile phase for separation, densitometric quantification, and MS confirmation (V5). Low-nanogram levels of thiamine, riboflavin, and niacin were quantified by fiber-optic fluorodensitometry after silica gel HPTLC with methanol-water (7:3) mobile phase (V6). Miscellaneous Organic Compounds. TLC methods for compounds that were not easily classified in, or were omitted from, the other applications sections are reviewed in this section. TLC of acetonitrile extracts on silica gel and diol layers was used to determine the principal polar aromatic flavor compounds of commercial cinnamons (W1). The retention behavior of azolidones was studied in normal and RP systems on silica gel and cellulose layers (W2), and benzamides were studied on cellulose, starch, and aminoplast layers (W3). Total saponin content and composition were assayed in quinoa plant tissue by TLC (W4). ω-Formal-functionalized polystyrenes were synthesized and characterized by hydroxylamine end-group titration, NMR spectroscopy, and TLC (W5). A semiquantitative visual determination of Tinuvin 622 in extracts derived from polyolefinic foodstuffs-packaging materials was performed on cellulose plates

developed with 2-propanol-25% acetic acid-toluene (10:10:1); the detection limit was 0.25 µg/spot with iodine vapor (W6). A method using amino-bonded HPTLC plates and 52% acetonitrile in 100 mM Tris-HCl buffer (pH 8.6) as the mobile phase allowed evaluation of the 7,8-dihydropteroate synthase reaction via determination of pteroic acid, obtained by chemical oxidation of the enzymic product dihydropteroic acid (W7). Anthraquinone glycosides in Rumex species grown in Turkey were determined by TLC on silica gel and C-18 plates (W8). A new solvent system consisting of hexane-acetone-tert-butyl alcohol (17:2:1) gave excellent separations of anthraquinone aglycons on both analytical and preparative scales (W9). Three TLC systems were used to investigate copoly(iminoacetals) from terephthaldehyde and aliphatic aminodiols (W10). n-Octyl β-D-glucopyranoside and ndodecyl β-D-maltoside were quantified in biological samples, e.g., thylakoid membranes, after separation on silica gel by development with chloroform-methanol-water (65:25:4) (W11). TLC on silica gel with methanol-pyridine-formamide (16:3:1) mobile phase and detection by inhibition of cholinesterase or ninhydrin reagent was used for analysis of technical products from the synthesis of dialkylaminoethyl dialkylamido fluorophosphates (W12). Thioindigoid thiazolidinone mixtures were quantified by separation on mixed silica gel-starch plates, scraping of zones, elution with DMSO, and visible spectrophotometry (W13). Flame retardants in Styrofoam were detected by dissolving in toluene, precipitating polystyrene with hexane, and TLC of the supernatant on silica gel with toluene-hexane (1:3) mobile phase and detection by silver nitrate; 1,2,5,6,9,10-hexabromocyclododecane was the most frequently detected retardant (W14). The silica gel TLC analysis of warfare agents and explosives was described in the following papers: a field kit of developing chambers and visualizing reagents and techniques for collection and analysis of samples of warfare agents under battlefield conditions (W15); explosives and their stabilizing agents and nitro compounds at contaminated warfare sites (W16); trace quantities of OP warfare agents based on cholinesterase inhibition by metal ions; the presence of Co2+ in the detection reagent decreased the detection limit to 1 pg/spot (W17); explosives and related compounds in soil and water near former ammunition production sites in Germany by AMD-HPTLC (W18); and identification of TNT and its biodegradation products in simulated pond water (W19). The use of densitometry was reported in the following quantitative determinations: residues of nitrofurans in eggs and milk using acetonitrile extraction, liquid-liquid partitioning cleanup, postchromatography in situ photoreaction with pyridine to form fluorescent ionic products, and double development silica gel TLC (W20); stabilizers (e.g., diphenylamine, ethylcentralite) and their reaction products in propellants on silica gel developed with hexane-benzene-ethyl acetate (8:3:2) or hexane-dichloromethane (7:5) (W21); 2-hydroxycinnamaldehyde in commercial cinnamons by solvent-assisted SFE, separation on bonded propanediol layers, and fluorescence scanning (W22); 5-(hydroxymethyl)-2-furfural in vanilla extracts by silica gel HPTLC with chloroform-ethyl acetate-1-propanol mobile phase and scanning at 280 nm (W23); ginseng saponins by 2-D TLC and dual-wavelength flying-spot scanning (W24); saponins in leaves of Hedera helix L. by silica gel TLC with chloroform-methanol-water (64:50:10) mobile phase, detection by spraying with vanillin reagent, and scanning at 565 nm (W25); and vanillin and related flavor compounds in

natural vanilla extracts and vanilla-flavored foods using AMD (W26). Planar chromatography methods for determining the quality of spices and flavors based on densitometric spectral scanning and quantification were reviewed (W27). Inorganics and Metal Organics. Reviews were written on novel applications of TLC in inorganic analysis for the period 1958-1991 (X1), PC and TLC in the analysis of inorganic pollutants (X2), recent trends in the separation and determination of rare earth elements (X3), and the use of silica gel and modified cellulose layers for analysis of inorganic mixtures (X4). The following systems were described for general or specific TLC or HPTLC separations of metal cations: RP layers with mono(2-ethylhexyl) acid phosphate as impregnant and nitric acid mobile phase for separation of 3d transition metal ions (X5); amine-treated silica gel for rare earths (X6); silica gel impregnated with a primary alkylamine and developed with sulfuric acid and sulfate mobile phases for 49 ions (X7); trimethylhydroxypropylamine cellulose with sulfuric acid-organic solvent mobile phases for 49 ions (X8); silica impregnated with a high molecular weight amine and sulfuric acid and sulfuric acid-ammonium sulfate mobile phases for 49 ions (X9); stannic sulfosalicylate layers with dimethylformamide (DMF) plus either nitric or hydrochloric acid as mobile phases for separation of uranium from 15 other metals (X10); lithium chloride-impregnated silica gel and alumina layers with formate-containing eluents for 15 metal ions (X11); Th4+-modified silica gel layers and 1.0 M sodium formate mobile phase in combination with spectrophotometry for determination of Zn in mixtures with Cd, Hg, and Ni (X12); and layers prepared from binary mixtures of different ratios of alumina, silica gel, and cellulose developed with aqueous methanol containing tributyl phosphate and methanol for cations and anions (X13). Iron(III) hexafluoro complex in the presence of thiocyanate was used as a new reagent for detection of Sn(II), Al(III), and Th(IV) ions after separation by PC (X14). Eight transition metals were separated on plain and impregnated (1,10-phenanthroline, dimethylglyoxime, EDTA) silica gel layers, detected with a new reagent (0.1% β-naphthol in methanol), and quantified by AAS (X15). The following studies of the TLC of metal complexes and chelates were reported: metal-EDTA complexes on silica gel G developed with mixed solvents containing DMF, THF, and pyridine (X16); salting-out TLC of 24 mixed neutral and anionic aminocarboxylatocobalt(III) complexes on silica gel, polyacrylonitrile, and cellulose sorbents with aqueous ammonium sulfate mobile phases (X17, X18); N,N-disubstituted dithiocarbamates of Ni and Co (X19); dipeptidato-Co(III) complexes on silica gel developed with aqueous ammonium sulfate solutions (X20); and platinum metal 8-hydroxyquinolates on polar stationary phases with chloroform-THF or -alcohol mobile phases (X21). Joseph Sherma received a B.S. in chemistry from Upsala College, East Orange, NJ, in 1955 and a Ph.D. in analytical chemistry from Rutgers University in 1958. He is currently John D. & Frances H. Larkin Professor and Head of the Department of Chemistry at Lafayette College. Dr. Sherma independently and with others has written or edited over 425 papers, chapters, books, and reviews covering chromatographic and analytical methods. He has been editor for residues and trace elements of the Journal of AOAC International for 15 years. He received the 1995 ACS Award for Research at an Undergraduate Institution, sponsored by Research Corp. LITERATURE CITED (1) Poole, C. F.; Poole, S. K. J. Chromatogr., A 1995, 703, 573-612. (2) Somsen, G. W.; Morden, W.; Wilson, I. D. J. Chromatogr., A 1995, 703, 613-665. (3) Busch, K. L. J. Planar Chromatogr.-Mod. TLC 1994, 7, 318321.


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(4) Davies, I. J. Planar Chromatogr.-Mod. TLC 1995, 8, 172-176. (5) Kaiser, R. E. J. Planar Chromatogr.-Mod. TLC, 1995, 8, 256. (6) Jaenchen, D. J. Planar Chromatogr.-Mod. TLC 1995, 8, 264. GENERAL CONSIDERATIONS History, Books, Reviews, and Student Experiments (A1) Bussemas, H.; Ettre, L. S. Chromatographia 1994, 38, 243254. (A2) Jork, H.; Funk, W.; Fischer, W.; Wimmer, H. Thin Layer Chromatography: Reagents and Detection Methods, Vol. 1b: Physical and Chemical Detection Methods: Activation Reactions, Reagents Sequences, Reagents II; VCH: Weinheim, Germany, 1994. (A3) Sherma, J.; Fried, B. Handbook of Thin Layer Chromatography, 2nd ed.; Marcel Dekker: New York, in press. (A4) Fried, B.; Sherma, J. Practical Thin Layer Chromatography: A Multidisciplinary Approach; CRC Press: Boca Raton, FL, in press. (A5) Jork, H. Am. Lab. (Shelton, Conn.) 1993, 25 (7), 36L, 36N, 36O. (A6) Jork, H. Am. Lab. (Shelton, Conn.) 1993, 25 (9), 24B-24F. (A7) Sherma, J. J. AOAC Int. 1994, 77, 297-306. (A8) Sherma, J. Rev. Anal. Chem. 1995, 14, 75-147. (A9) Herold, A. J. Planar Chromatogr.-Mod. TLC 1994, 7, 180196. (A10) Jeger, A. N.; Briellmann, T. A. J. Planar Chromatogr.-Mod. TLC 1994, 7, 157-159. (A11) Cawley, J. J. J. Chem. Educ. 1995, 72, 272-273. (A12) Reynolds, R. C.; Comber, R. N. J. Chem. Educ. 1994, 71, 10751077. (A13) Baumbach, E. Math. Naturwiss. Unterr. 1994, 47, 270-273. (A14) Nagel, R. Math. Naturwiss. Unterr. 1994, 47, 425. (A15) Seaton, P.; Zimmer, J. Biochem. Educ. 1993, 21, 216-217. (A16) Redeker, J. Prax. Naturwiss., Chem. 1995, 44, 34-36; Chem. Abstr. 1995, 123, 284735z. Theory and Fundamental Studies (B1) Davis, J. M. Adv. Chromatogr. (N.Y.) 1994, 34, 109-176. (B2) Woolston, C. R. J.; Lee, J. B.; Swinbourne, F. J. Indian J. Chem., Sect. B: Org. Chem. Ind. Med. Chem. 1994, 33B, 590-592; Chem. Abstr. 1994, 121, 34737c. (B3) Vuckovic, G.; Miljevic, D.; Janjic, T. J.; Djuran, M. I.; Celap, M. B. Chromatographia 1995, 40, 445-447. (B4) Sabbu, C.; Nascu, H. Rev. Roum. Chim. 1992, 37, 945-951. (B5) Merkku, P.; Yliruusi, J.; Vuorela, H. J. Planar Chromatogr.Mod. TLC 1995, 8, 112-116. (B6) Merkku, P.; Yliruusi, J.; Vuorela, H.; Hiltunen, R. J. Planar Chromatogr.-Mod. TLC 1994, 7, 305-308. (B7) Cserhati, T. Biomed. Chromatogr. 1994, 8, 45-48. (B8) Dzido, T. H.; Polak, B. J. Planar Chromatogr.-Mod. TLC 1993, 6, 378-381. (B9) Cavalli, E. J.; Guinchard, C. Chromatographia 1993, 37, 107109. (B10) Pyka, A. J. Planar Chromatogr.-Mod. TLC 1994, 7, 41-49. (B11) Pyka, A. J. Planar Chromatogr.-Mod. TLC 1995, 8, 52-62. (B12) Pyka, A. J. Planar Chromatogr.-Mod. TLC 1994, 7, 389-393. (B13) Anton-Fos, G. M.; Garcia-March, F. J.; Perez-Giminez, F.; Salabert-Salvador, M. T.; Cercos-del-Pozo, R. A. J. Chromatogr., A 1994, 672, 203-211. (B14) Bazylak, G. Chem. Anal. (Warsaw) 1994, 39, 295-308. (B15) Bazylak, G. J. Planar Chromatogr.-Mod. TLC 1994, 7, 202210. (B16) Pyka, A. J. Planar Chromatogr.-Mod. TLC 1994, 7, 108-116. (B17) Bazylak, G. J. Planar Chromatogr.-Mod. TLC 1994, 7, 428434. (B18) Baranowska, I.; Swierczek, S. J. Planar Chromatogr.-Mod. TLC 1994, 7, 399-405. (B19) Baranowska, I.; Swierczek, S. J. Planar Chromatogr.-Mod. TLC 1994, 7, 251-253. (B20) Cserhati, T.; Forgacs, E. J. Chromatogr., A 1994, 685, 295302. (B21) Cserhati, T.; Forgacs, E. Chemom. Intell. Lab. Syst. 1995, 28, 305-313. (B22) Forgacs, E. Anal. Lett. 1994, 27, 1075-1093. (B23) Kowalska, T.; Klama, B. J. Planar Chromatogr.-Mod. TLC 1994, 7, 147-152. (B24) Lepri, L.; Coas, V.; Desideri, P. G. J. Planar Chromatogr.-Mod. TLC 1994, 7, 103-107. (B25) Nurok, D.; Kleyle, R. M.; Lipkowitz, K. B.; Myers, S. S.; Kearns, R. M. Anal. Chem. 1993, 65, 3701-3707. (B26) Podgorny, A.; Kowalska, T. J. Planar Chromatogr.-Mod. TLC 1994, 7, 217-220. (B27) Podgorny, A.; Kowalska, T. J. Planar Chromatogr.-Mod. TLC 1994, 7, 291-293. (B28) Waksmundzka-Hajnos, M.; Zareba, S.; Chabros, A. Chem. Anal. (Warsaw) 1994, 39, 121-132. (B29) Waksmundzka-Hajnos, M. Chem. Anal. (Warsaw) 1994, 39, 455-466. (B30) Tesic, Z. L.; Janjic, T. J.; Tosic, R. M.; Celap, M. B. Chromatographia 1993, 37, 599-602. (B31) Baranowska, L.; Swierczek, S. Acta Chromatogr. 1994, 3, 5969. (B32) Cserhati, T. Anal. Chim. Acta 1994, 292, 17-22. 14R


(B33) Janjic, T. J.; Zivkovic, V.; Celap, M. B. Chromatographia 1994, 38, 355-358. (B34) Janjic, T. J.; Zivkovic, V.; Celap, M. B. Chromatographia 1993, 37, 534-538. (B35) Golkiewicz, W.; Polak, B. J. Planar Chromatogr.-Mod. TLC 1994, 7, 453-457. (B36) Prus, W.; Kowalska, T. J. Planar Chromatogr.-Mod. TLC 1995, 8, 205-215. (B37) Malinowska, I.; Rozylo, J. K.; Gumieniak, A. J. Planar Chromatogr.-Mod. TLC 1995, 8, 23-32. (B38) Malinowska, I.; Rozylo, J. K. J. Planar Chromatogr.-Mod. TLC 1993, 6, 452-457. (B39) Prus, W.; Kowalska, T. J. Planar Chromatogr.-Mod. TLC 1995, 8, 288-291. (B40) Markowski, W.; Czapinska, K. L. J. Liq. Chromatogr. 1995, 18, 1405-1427. (B41) Matyska, M.; Soczewinski, E. Chem. Anal. (Warsaw) 1993, 38, 555-563. (B42) Wang, Q.-S.; Yan, B.-W.; Zhang, Z.-C. J. Planar Chromatogr.Mod. TLC 1994, 7, 477-480. (B43) Wang, Q.-S.; Yan, B.-W.; Zhang, Z.-C. J. Planar Chromatogr.Mod. TLC 1994, 7, 229-232. (B44) Wang, Q.-S.; Yan, B.-W.; J. Planar Chromatogr.-Mod. TLC 1993, 6, 296-299. (B45) Wang, Q.-S.; Yan, B.-W.; Zhang, L. Chromatographia 1995, 40, 463-466. (B46) Wang, Q.-S.; Zhan, Z.-P. J. Planar Chromatogr.-Mod. TLC 1994, 7, 394-398. (B47) Janicka, M.; Rozylo, J. K. J. Planar Chromatogr.-Mod. TLC 1993, 6, 362-367. (B48) Rozylo, J. K.; Janicka, M.; Siembida, R. J. Liq. Chromatogr. 1994, 17, 3641-3653. (B49) Bilesner, D. M. J. Planar Chromatogr.-Mod. TLC 1994, 7, 197201. (B50) Cserhati, T.; Forgacs, E. J. Chromatogr., A 1994, 668, 495500. (B51) Vuorela, P.; Rahko, E.-L.; Hiltunen, R.; Vuorela, H. J. Chromatogr., A 1994, 670, 191-198. (B52) Biagi, G. L.; Barbaro, A. M.; Sapone, A.; Recanatini, M. J. Chromatogr. 1994, 662, 341-361. (B53) Sonntag, C.; Mannhold, R. J. Chromatogr., A 1994, 673, 113124. (B54) Biagi, G. L.; Barbaro, A. M.; Recanatini, M. J. Chromatogr., A 1994, 678, 127-137. (B55) Gocan, S.; Irimie, F.; Cimpan, G. J. Chromatogr., A 1994, 675, 282-285. (B56) Forgacs, E.; Cserhati, T. J. Chromatogr., A 1995, 697, 5969. (B57) Darwish, Y.; Cserhati, T.; Forgacs, E. J. Chromatogr., A 1994, 668, 485-494. (B58) Biagi, G. L.; Barbaro, A. M.; Sapone, A.; Recanatini, M. J. Chromatogr., A 1994, 669, 246-253. (B59) Kalasz, H.; Kerecsen, L.; Csermely, T.; Goetz, H.; Friedmann, T.; Hosztafi, S. J. Planar Chromatogr.-Mod. TLC 1995, 8, 1722. Chromatographic Systems (Stationary and Mobile Phases) (C1) Hauck, H. E.; Junker-Buchheit, A.; Wenig, R.; Schoemer, S. LaborPraxis 1995, 19, 70-2, 109-110 (spec. Labor 2000); Chem. Abstr. 1995, 122, 204170c. (C2) Hahn-Deinstrop, E. J. Planar Chromatogr.-Mod. TLC 1993, 6, 313-318. (C3) Hajouj, Z.; Thomas, J.; Siouffi, A. M. Analusis 1994, 22, 404407; Chem. Abstr. 1995, 123, 73822n. (C4) Hajouj, Z.; Thomas, J.; Siouffi, A. M. J. Liq. Chromatogr. 1995, 18, 887-894. (C5) Khan, M. U.; Williams, J. P. Lipids 1993, 28, 953-955. (C6) Hauck, H. E.; Junker-Buchheit, A.; Wenig, R. LC-GC Int. 1995, 8 (1), 34, 36-38. (C7) Flodberg, G.; Roeraade, J. J. Planar Chromatogr.-Mod. TLC 1993, 6, 252-255. (C8) Kriz, D.; Kriz, C. B.; Andersson, L. L.; Mosbach, K. H. Anal. Chem. 1994, 66, 2636-2639. (C9) Coman, V.; Marutiou, C. J. Planar Chromatogr.-Mod. TLC 1994, 7, 450-452. (C10) Hadzija, O.; Spoljar, B.; Sesartic, L. Fresenius’ J. Anal. Chem. 1994, 348, 782. (C11) Mohammad, A.; Khan, M. A. M. J. Chromatogr. 1993, 642, 455-458. (C12) Mohammad, A.; Fatima, N.; Khan, M. A. M. J. Planar Chromatogr.-Mod. TLC 1994, 7, 142-146. (C13) Kovacs-Hadady, K.; Balazs, E. J. Planar Chromatogr.-Mod. TLC 1993, 6, 463-466. (C14) Poole, C. F.; Fernando, W. P. N. J. Planar Chromatogr.-Mod. TLC 1993, 6, 357-361. (C15) Shtykov, S. N.; Sumina, E. G.; Parshina, E. V.; Lopukhova, S. S. J. Anal. Chem. (Moscow) 1995, 50, 684-688 (transl of Zh. Anal. Khim.); Chem. Abstr. 1995, 123, 274786c. (C16) Soczewinski, E.; Maciejewicz, W. J. Planar Chromatogr.-Mod. TLC 1994, 7, 153-156. (C17) Huynh, T. K. X.; Lederer, M.; Leipzig-Pagani, E. J. Chromatogr., A 1995, 695, 155-159. (C18) Huynh, T. K. X.; Lederer, M.; Leipzig-Pagani, E. J. Chromatogr., A 1995, 695, 160-164.

(C19) Politzer, I. R.; Crago, K. T.; Hollin, T.; Young, M. J. Chromatogr. Sci. 1995, 33, 316-320. (C20) Levin, M.; Grizodoub, A.; Asmolova, N.; Grigorieva, V.; Georgievsky, V. Chromatographia 1993, 37, 517-524. (C21) Bieganowska, M. I.; Petruczynik, A. Chem. Anal. (Warsaw) 1994, 39, 445-454. (C22) Lepri, L.; Coas, V.; Desideri, P. G. J. Planar Chromatogr.-Mod. TLC 1994, 7, 322-326. (C23) Xuan, H. T. K.; Lederer, M. J. Chromatogr. 1994, 659, 191197. (C24) Lepri, L.; Coas, V.; Desideri, P. G.; Zocchi, A. J. Planar Chromatogr.-Mod. TLC 1994, 7, 376-381. (C25) Hinze, W. L.; Feng, L.-w.; Moreno, B.; Quina, F. H.; Suzuki, Y.; Wang, H. Anal. Sci. 1995, 11, 183-187. (C26) Armstrong, D. W.; Zhou, Y. J. Liq. Chromatogr. 1994, 17, 1695-1707. Apparatus and Techniques (D1) Poole, C. F.; Poole, S. K. Anal. Chem. 1994, 66, 27A-37A. (D2) Nores, G. A.; Mizutamari, R. K.; Kremer, D. M. J. Chromatogr., A 1994, 686, 155-157. (D3) Waksmundzka-Hajnos, M.; Wawrzynowicz, T. J. Planar Chromatogr.-Mod. TLC 1994, 7, 58-62. (D4) Matysik, G.; Wojtasik, E. J. Planar Chromatogr.-Mod. TLC 1994, 7, 34-37. (D5) Fateley, W. G.; Hammaker, R. M.; Paukstelis, J. V.; Wright, S. L.; Orr, E. A.; Mortensen, A. N.; Latas, K. J. Appl. Spectrosc. 1993, 47, 1464-1470. (D6) Flodberg, G.; Roeraade, J. J. Planar Chromatogr.-Mod. TLC 1995, 8, 10-13. (D7) Freeman, M.; Stead, A.; Stroud, R. J. Planar Chromatogr.-Mod. TLC 1993, 6, 419-421. (D8) Poole, C. F.; Poole, S. K.; Belay, M. T. J. Planar Chromatogr.Mod. TLC 1993, 6, 438-445. (D9) Delvordre, P.; Sarbach, C.; Postaire, E. Analusis 1992, 22, 31-34. (D10) Bonnier, H.; Delvordre, P.; Postaire, E. J. Planar Chromatogr.Mod. TLC 1994, 7, 117-121. (D11) Nyiredy, Sz.; Fater, Z. J. Planar Chromatogr.-Mod. TLC 1994, 7, 329-333. (D12) Matysik, G. Chromatographia 1994, 38, 109-113. (D13) Kalasz, H.; Bathori, M.; Ettre, L. S.; Polyak, B. J. Planar Chromatogr.-Mod. TLC 1993, 6, 481-486. (D14) Vegh, Z. J. Planar Chromatogr.-Mod. TLC 1993, 6, 341-345. (D15) Reinhartz, A.; Alajem, S.; Samson, A.; Herzberg, M. Gene 1993, 136, 221-226. (D16) Zamora, P. O.; Sasa, K.; Cardillo, A. S.; Lambert, C. R.; Budd, P.; Marek, M. J.; Rhoades, B. A. BioTechniques 1994, 16, 306-308, 310-311. (D17) Nilsson, S.; Lager, C.; Laurell, T.; Birnbaum, S. Anal. Chem. 1995, 67, 3051-3056. (D18) Muething, J.; Unland, F. Glycoconjugate J. 1994, 11, 486492. (D19) Watanabe, K.; Nishiyama, M. Anal. Biochem. 1995, 227, 195200. (D20) Lickl, E. Oesterr. Chem. Z. 1995, 96, 123-124; Chem. Abstr. 1995, 123, 305221w. (D21) Safronova, N. S.; Matveeva, S. S.; Fabelinsky, Y. I.; Ryabukhin, V. A. Analyst (Cambridge, U.K.) 1995, 120, 1427-1432. (D22) Banks, C. T. J. Pharm. Biomed. Anal. 1993, 11, 705-710. (D23) Moersel, J. T.; Huth, M.; Seifert, K. LaborPraxis 1991, 19, 24-26; Chem. Abstr. 1995, 123, 110356m. (D24) Esser, G.; Klockow, D. Mikrochim. Acta 1994, 113, 373-379. (D25) Delvordre, P.; Postaire, E. J. Planar Chromatogr.-Mod. TLC 1993, 6, 289-293. (D26) Buhlmann, R.; Carmona, J.; Donzel, A.; Donzel, N.; Gil, J. J. Chromatogr. Sci. 1994, 32, 243-248. (D27) Zieloff, K. Oesterr. Chem. Z. 1995, 96, 120-122; Chem. Abstr. 1995, 123, 305319j. Detection and Identification of Separated Zones (E1) Szabady, B. J. Planar Chromatogr.-Mod. TLC 1994, 7, 406409. (E2) Wagner, J.; Jork, H.; Koglin, E. J. Planar Chromatogr.-Mod. TLC 1993, 6, 446-451. (E3) Klaus, R.; Fischer, W.; Hauck, H. E. LC-GC 1995, 13, 816, 818, 820-822. (E4) Fenske, M. Chromatographia 1995, 41, 175-177. (E5) Konopski, L.; Pawlowska, E. J. Chromatogr., A 1994, 669, 275-276. (E6) Kotynski, A.; Kudzin, Z. H. J. Chromatogr. 1994, 663, 127131. (E7) Patil, V. B.; Shingare, M. S. Analyst (Cambridge, U.K.) 1994, 119, 415-416. (E8) Riemer, E.; Daldrup, T. Pharmazie 1992, 47, 559; Chem. Abstr. 1994, 120, 25113y. (E9) Wardas, W.; Pyka, A.; Jedrzejczak, M. J. Planar Chromatogr.Mod. TLC 1993, 6, 238-241. (E10) Taki, T. Fragrance J. 1994, 22, 85-90. (E11) Taki, T.; Handa, S.; Ishikawa, D. Anal. Biochem. 1994, 221, 312-316. (E12) Sorice, M.; Griggi, T.; Circella, A.; Garafolo, T.; d’Agostino, F.; Pittoni, V.; Pontieri, G. M.; Lenti, L.; Valesini, G. J. Immunol. Methods 1994, 173, 49-54.

(E13) Saxena, G.; Farmer, S.; Towers, G. H. N.; Hancock, R. E. W. Phytochem. Anal. 1995, 6, 125-129. (E14) Van de Nesse, R. J.; Vinkengurg, I. H.; Jonker, R. H. J.; Hoornweg, G. Ph.; Gooijer, C.; Brinkman, U. A. T.; Velthorst, N. H. Appl. Spectrosc. 1994, 48, 788-795. (E15) Wu, N.; Hule, C. W. J. Planar Chromatogr.-Mod. TLC 1994, 7, 88-94. (E16) Keller, S.; Loechte, T.; Dippel, B.; Schrader, B. Fresenius’ J. Anal. Chem. 1993, 346, 863-867. (E17) Wright, S. L.; Latas, K. J.; Mortensen, A. N.; Orr, E. A.; Paukstelis, J. V.; Hammaker, R. M.; Fateley, W. G. Proc. SPIEInt. Soc. Opt. Eng. 1993, 1857, 135-145; Chem. Abstr. 1994, 120, 123635q. (E18) Koglin, E. GIT Fachz. Lab. 1994, 38, 627-628, 630-632; Chem. Abstr. 1994, 121, 72718e. (E19) Bouffard, S. P.; Katon, J. E.; Sommer, A. J.; Danielson, N. D. Anal. Chem. 1994, 66, 1937-1940. (E20) Buschmann, N.; Kruse, A. Comun. Jorn. Com. Esp. Deterg. 1993, 24, 457-468. (E21) Chambuso, M.; Kovar, K.-A.; Zimmermann, W. Pharmazie 1994, 49, 142-148. (E22) Fong, A.; Hieftje, G. M. Appl. Spectrosc. 1994, 48, 394-399. (E23) Wolff, S. C.; Kovar, K.-A. J. Planar Chromatogr.-Mod. TLC 1994, 7, 344-348. (E24) Wolff, S. C.; Kovar, K.-A. J. Planar Chromatogr.-Mod. TLC 1994, 7, 286-290. (E25) Yao, Z.; Wen, H.; Zha, Q.; He, W.; Zhao, S. Rapid Commun. Mass Spectrom. 1994, 8, 481-483. (E26) Yassin, A. F.; Haggenei, B.; Budzikiewicz, H.; Schaal, K. P. Int. J. Syst. Bacteriol. 1993, 43, 414-420. (E27) Taki, T.; Ishikawa, D.; Handa, S.; Kasama, T. Anal. Biochem. 1995, 225, 24-27. (E28) Oka, H.; Ikai, Y.; Ohno, T.; Kawamura, N.; Hayakawa, J.; Harada, K.-i.; Suzuki, M. J. Chromatogr., A 1994, 674, 301307. (E29) Oka, H.; Ikai, Y.; Hayakawa, J.; Masuda, K.; Harada, K.-i.; Suzuki, M. J. AOAC Int. 1994, 77, 891-895. (E30) Chai, W.; Rosankiewicz, J. R.; Lawson, A. M. Carbohydr. Res. 1995, 269, 111-124. (E31) Morden, W.; Wilson, I. D. J. Planar Chromatogr.-Mod. TLC 1995, 8, 98-102. (E32) Lafont, R.; Porter, C. J.; Williams, E.; Read, H.; Morgan, E. D.; Wilson, I. D. J. Planar Chromatogr.-Mod. TLC 1993, 6, 421424. (E33) de Koster, C. G.; Vos, B.; Versluis, C.; Heerma, W.; Haverkamp, J. Biol. Mass Spectrom. 1994, 23, 179-185. (E34) Krutchinsky, A. N.; Dolgin, A. I.; Utsal, O. G.; Khodorkovski, A. M. J. Mass Spectrom. 1995, 30, 375-379. (E35) Fanibanda, T.; Milnes, J.; Gormally, J. Int. J. Mass Spectrom. Ion Processes 1994, 140, 127-132. (E36) Gusev, A. I.; Procter, A.; Rabinovich, Y. I.; Hercules, D. M. Anal. Chem. 1995, 67, 1805-1814. Quantitative Analysis (F1) Aginsky, V. N. J. Planar Chromatogr.-Mod. TLC 1994, 7, 309314. (F2) Nagy-Turak, A.; Vegh, Z. J. Planar Chromatogr.-Mod. TLC 1995, 8, 188-193. (F3) Navas Diaz, A.; Garcia Sanchez, F. Instrum. Sci. Technol. 1994, 22, 273-281. (F4) Baker, M.; Denton, M. B. In Charge-Transfer Devices in Spectroscopy; Sweedler, J. V., Ratzlaff, K. L., Denton, M. B., Eds.; VCH: New York, 1994; pp 197-226; Chem. Abstr. 1995, 123, 131585a. (F5) Spangenberg, B.; Stehle, S.; Stroebele, C. GIT Fachz. Lab. 1995, 39, 461-462, 464; Chem. Abstr. 1995, 123, 187192n. (F6) Guilleux, J. C.; Barnouin, K. N.; Ricchiero, F. A.; Lerner, D. A. J. Liq. Chromatogr. 1994, 17, 2821-2831. (F7) Garcia Sanchez, F.; Navas Diaz, A.; Fernandez Correa, M. R. J. Chromatogr. 1993, 655, 31-38. (F8) Bharati, S.; Roestrum, G. A.; Loeberg, R. Org. Geochem. 1994, 22, 835-862. Preparative-Layer Chromatography and Radio-Thin-Layer Chromatography (G1) Laeufer, K.; Lehmann, J.; Petry, S.; Scheuring, M.; SchmidtSchuchardt, M. J. Chromatogr., A 1994, 684, 370-373. (G2) Matysik, G.; Soczewinski, E.; Polak, B. Chromatographia 1994, 39, 497-504. (G3) Kristensen, S.; Grislingaas, A. L.; Greenhill, J. V.; Skjetne, T.; Karlsen, J. Int. J. Pharm. 1993, 100, 15-23. (G4) Kennedy Keller, R.; Thompson, R. J. Chromatogr. 1993, 645, 161-167. (G5) Deleva, D. D.; Ilinov, P. P.; Zaprianova, E. T. Bulg. Chem. Commun. 1992, 25, 514-519; Chem. Abstr. 1994, 120, 186406m. (G6) Wawrzynowicz, T.; Waksmundzka-Hajnos, M.; Mulak-Banaszek, K. J. Planar Chromatogr.-Mod. TLC 1994, 7, 315-317. (G7) Vingler, P.; Filthuth, H.; Bague, A.; Pruche, F.; Kermici, M. Steroids 1993, 58, 429-438. (G8) Hazal, I.; Urmos, I.; Klebovich, I. J. Planar Chromatogr.-Mod. TLC 1995, 8, 92-97. (G9) Nagatsuka, S.-i.; Ueda, K.; Ninomiya, S.-i.; Esumi, Y. Yakubutsu Dotai 1993, 8, 1261-1271; Chem. Abstr. 1994, 121, 103106k.


15R

(G10) Ueda, K.; Ninomiya, S.-i.; Esumi, Y.; Shimada, N.; Nagatsuka, S.-i. Yakubutsu Dotai 1993, 8, 1273-1282; Chem. Abstr. 1994, 121, 98931u. (G11) Klein, O.; Clark, T. J. Planar Chromatogr.-Mod. TLC 1993, 6, 368-371. (G12) Zamora, P. O.; Domalewski, M. D.; Marek, M. J.; Budd, P.; Rhodes, B. A. Nucl. Med. Biol. 1994, 21, 205-210. (G13) van Waarde, A.; Anthonio, R. L.; Visser, T. J.; Elsinga, P. H.; Posthumus, H.; Weemaes, A.-M. A.; Blanksma, P. K.; Visser, G. M.; Paans, A. M. J. J. Chromatogr., B 1995, 663, 361-369. (G14) Gattavecchia, E.; Tonelli, D.; Breccia, A.; Fini, A.; Ferri, E. J. Radioanal. Nucl. Chem. 1994 181, 77-84. (G15) Tonelli, D.; Zappoli, S.; Marengo, M. Appl. Radiat. Isot. 1994, 45, 549-552. (G16) Green, M. J.; Donohoe, M. E.; Foster, M. E.; Glajch, J. L. J. Nucl. Med. Technol. 1994, 22, 21-26. (G17) Tal, A.; Rubin, B. Pestic. Sci. 1993, 39, 207-212. (G18) Singh, S. P.; Moody, D. E. J. Pharm. Biomed. Anal. 1995, 13, 1027-1032. (G19) Nadeau, L. J.; Menn, F. M.; Breen, A.; Sayler, G. S. Appl. Environ. Microbiol. 1994, 60, 51-55. (G20) Kornyei, J.; Torko, J.; Volford, J. J. Radioanal. Nucl. Chem. 1994, 186, 189-197. (G21) Koopdonk-Kool, J. M.; van Lopik-Peterse, M. C.; Veenboer, G. J. M.; Visser, T. J.; Schoenmakers, C. H. H.; de Vijlder, J. J. M. Anal. Biochem. 1993, 214, 329-331. (G22) Kasahara, K.; Guo, L.; Nagai, Y.; Sanai, Y. Anal. Biochem. 1994, 218, 224-226. (G23) Foster, J. M.; Pennock, J. F.; Marshall, I.; Rees, H. H. Mol. Biochem. Parasitol. 1993, 61, 275-284. (G24) Cajigas, A.; Gayer, M.; Beam, C.; Steinberg, J. J. Arch. Environ. Health 1994, 49, 25-36. (G25) Agarwal, H. C.; Singh, D. K.; Sharma, V. B. J. Environ. Sci. Health, Part B 1994, B29, 87-96.

(I15) Petrovic, M.; Kastelan-Macan, M. J. Chromatogr., A 1995, 704, 173-178. (I16) Dehtiar, W. G.; Tyaglov, B. V.; Degterev, E. V.; Krylov, V. M.; Malakhova, I. I.; Krasikov, V. D. J. Planar Chromatogr.-Mod. TLC 1994, 7, 54-57. (I17) Das, B.; Sawant, S. J. Planar Chromatogr.-Mod. TLC 1993, 6, 294-295. (I18) El-Thaher, T. S.; Bailey, G. S. Anal. Biochem. 1994, 217, 335337. (I19) Van Der Geer, P.; Luo, K.; Sefton, B. M.; Hunter, T. In Protein Phosphorylation; Hardie, D. G., Ed.; IRL: Oxford, U.K., 1993; pp 31-59; Chem. Abstr. 1994, 120, 293156b. (I20) Song, Y. M.; Yoo, G. S.; Lee, S. K.; Choi, J. K. Arch. Pharmacol. Res. 1993, 16, 99-103. Antibiotics (J1) Schwaiger, I.; Hoertner, H. Wien. Tieraerztl. Monatsschr. 1992, 79, 365-369; Chem. Abstr. 1994, 120, 29575y. (J2) Naidong, W.; Hua, S.; Roets, E.; Hoogmartens, J. J. Planar Chromatogr.-Mod. TLC 1994, 7, 297-300. (J3) Roets, E.; Adams, E.; Muriithi, I. G.; Hoogmartens, J. J. Chromatogr., A 1995, 696, 131-138. (J4) Naidong, W.; Hua, S.; Roets, E.; Hoogmartens, J. J. Pharm. Biomed. Anal. 1995, 13, 905-910. (J5) Funk, W.; Kuepper, T.; Wirtz, A.; Netz, S. J. Planar Chromatogr.Mod. TLC 1994, 7, 10-13. (J6) Vega, M.; Garcia, G.; Saelzer, R.; Vilegas, R. J. Planar Chromatogr.-Mod. TLC 1994, 7, 159-162. (J7) Vega, M., Garcia, G.; Saelzer, R. J. Planar Chromatogr.-Mod. TLC 1993, 6, 208-211. (J8) Schuck, D. F.; Pavlina, T. M. J. Planar Chromatogr.-Mod. TLC 1994, 7, 242-246. Bases and Amines

APPLICATIONS Acids and Phenols (H1) Bieganowska, M. L.; Petruczynik, A.; Glowniak, K. J. Planar Chromatogr.-Mod. TLC 1995, 8, 63-68. (H2) Baranowska, I.; Skotniczna, A. Chromatographia 1994, 39, 564-568. (H3) Bund, O.; Fischer, W.; Hauck, H. E. J. Planar Chromatogr.Mod. TLC 1995, 8, 300-305. (H4) Lalaguna, F. J. Chromatogr. 1993, 657, 445-449. (H5) Amarowicz, R.; Rudnicka, B.; Ciska, E. Pol. J. Food Nutr. Sci. 1994, 3, 159-162; Chem. Abstr. 1995, 123, 168093q. (H6) Smolarz, H. D.; Waksmundzka-Hajnos, M. J. Planar Chromatogr.-Mod. TLC 1993, 6, 278-281. (H7) Wardas, W.; Pyka, A.; Jedrzejczak, M. J. Planar Chromatogr.Mod. TLC 1995, 8, 148-151. (H8) Kaouadji, M.; Morand, J. M.; Garcia, J. J. Nat. Prod. 1993, 56, 1618-1621. (H9) Madelaine-Dupuich, C.; Azema, J.; Escoula, B.; Rico, L.; Lattes, A. J. Chromatogr. 1993, 653, 178-180. (H10) Sarbach, Ch.; Postaire, E.; Sauzieres, J. J. Liq. Chromatogr. 1994, 17, 2737-2749. (H11) Shi, R.; Schwedt, G. Dtsch. Lebensm.-Rundsch. 1995, 91, 1417. (H12) Agbaba, D.; Stojanov, M.; Rajacic, S.; Zivanov-Stakic, D.; MajkicSingh, N. Clin. Chem. (Washington, D.C.) 1993, 39, 25002503. (H13) Khan, S. H.; Murawski, M. P.; Sherma, J. J. Liq. Chromatogr. 1994, 17, 855-865. (H14) Smith, M. C.; Sherma, J. J. Planar Chromatogr.-Mod. TLC 1995, 8, 103-106. Amino Acids, Peptides, and Proteins (I1) Siddiqi, Z. M.; Rani, S. J. Planar Chromatogr.-Mod. TLC 1995, 8, 141-143. (I2) Bhushan, R.; Parshad, V. J. Planar Chromatogr.-Mod. TLC 1994, 7, 480-483. (I3) Bhushan, R.; Mahesh, V. K.; Varma, A. Biomed. Chromatogr. 1994, 8, 69-72. (I4) Norfolk, E.; Khan, S. H.; Fried, B.; Sherma, J. J. Liq. Chromatogr. 1994, 17, 1317-1326. (I5) Sinhababu, A.; Basak, B.; Laskar, S. Anal. Proc. 1994, 31, 6566. (I6) Pyka, A. J. Planar Chromatogr.-Mod. TLC 1993, 6, 282-288. (I7) Jork, H.; Ganz, J. L-Tryptophan: Curr. Prospects Med Drug Saf. 1994, 338-350; Chem. Abstr. 1995, 123, 41025p. (I8) Aboul-Enein, J. Y.; Serignese, V. Biomed. Chromatogr. 1994, 8, 317-318. (I9) Bhushan, R.; Reddy, G. P.; Joshi, S. J. Planar Chromatogr.-Mod. TLC 1994, 7, 126-128. (I10) Mathur, V.; Kanoongo, N.; Mathur, R.; Narang, C. K.; Mathur, N. K. J. Chromatogr., A 1994, 685, 360-364. (I11) LeFevre, J. W. J. Chromatogr. 1993, 653, 293-302. (I12) Hao, A.-Y.; Tong, L.-H.; Zhang, F.-S.; Gao, X.-M.; Inou, Y. Anal. Lett. 1995, 28, 2041-2048. (I13) Ohtake, H.; Hase, Y.; Sakemoto, K.; Oura, T.; Wada, Y.; Kodama, H. Screening 1995, 4, 17-26. (I14) Clift, J.; Hall, S. K.; Carter, R. A.; Denmeade, R.; Green, A. Screening 1994, 3, 39-43. 16R


(K1) Mohammad, A.; Ajmal, M.; Anwar, S. J. Planar Chromatogr.Mod. TLC 1995, 8, 216-218, (K2) Mohammad, A.; Ajmal, M.; Anwar, S. J. Chromatogr. Sci. 1995, 33, 383-385. (K3) Bieganowska, M. L.; Doraczynska-Szopa, A.; Petruczynik, A. J. Planar Chromatogr.-Mod. TLC 1995, 8, 122-128. (K4) Matyska, M. T.; Siouffi, A. M.; Volpe, N. J. Planar Chromatogr.Mod. TLC 1995, 8, 39-46. (K5) Heuser, D.; Meads, P. J. Planar Chromatogr.-Mod. TLC 1993, 6, 324-325. (K6) Jain, R.; Gupta, S. J. Indian Chem. Soc. 1994, 71, 709-710. (K7) Klaus, R.; Fischer, W.; Hauck, H. E. Chromatographia 1993, 37, 133-143. (K8) Alemany, G.; Nicolau, M. C.; Gamundi, A.; Rial, B. Biomed. Chromatogr. 1993, 7, 315-316. (K9) Naguib, K.; Ayesh, A. M.; Shalaby, A. R. J. Agric. Food Chem. 1995, 43, 134-139. (K10) Shalaby, A. R. Food Chem. 1995, 52, 367-372. (K11) Shalaby, A. R. Food Chem. 1994, 49, 305-310. Carbohydrates (L1) Zarzycki, P. K.; Nowakowska, J.; Chmielewaka, A.; Lamparczyk, H. J. Planar Chromatogr.-Mod. TLC 1995, 8, 227-231. (L2) Szilagyi, J.; Kovacs-Hadady, K.; Kovacs, A. J. Planar Chromatogr.-Mod. TLC 1993, 6, 212-215. (L3) Kharbade, B. V.; Joshi, G. P. Stud. Conserv. 1995, 40, 93102. (L4) Yao, Z.; Liu, G.; Wen, H.; He, W.; Zhao, S.; Hu, W. J. Planar Chromatogr.-Mod. TLC 1994, 7, 410-412. (L5) Lodi, G.; Betti, A.; Brandolini, V.; Menziani, E.; Tosi, B. J. Planar Chromatogr.-Mod. TLC 1994, 7, 29-33. (L6) Robyt, J. F.; Mukerjea, R. Carbohydr. Res. 1994, 251, 187202. (L7) Perez, M. K.; Fried, B.; Sherma, J. J. Parasitol. 1994, 80, 336338. (L8) Conaway, C. A.; Fried, B.; Sherma, J. J. Planar Chromatogr.Mod. TLC 1995, 8, 184-187. (L9) Esaiassen, M.; Oeverboe, K.; Olsen, R. L. Carbohydr. Res. 1995, 273, 77-81. Dyes and Pigments (M1) Sweeney, E. G.; Schmidt, C. H.; Zimin, A.; Caputo, P. A.; Anderson, P. M. Soc. Automot. Eng., [Spec. Publ.] 1994, SP1056, 1-9; Chem. Abstr. 1995, 122, 218059k. (M2) Mariani, E.; Bargagna, A.; Longobardi, M.; Dorato, S. Int. J. Cosmet. Sci. 1994, 16, 17-27. (M3) Wall, P. E. J. Planar Chromatogr.-Mod. TLC 1993, 6, 394403. (M4) Dugar, S. M.; Leibowitz, J. N. J. AOAC Int. 1994, 77, 13351337. (M5) Ahmed, A. K. S.; Fattah, L. E. A.; El-Gendy, A. E. Egypt. J. Pharm. Sci. 1992, 33, 485-501. (M6) Aginsky, V. N. J. Forensic Sci. 1993, 38, 1131-1133. (M7) Aginsky, V. N. J. Forensic Sci. 1993, 38, 1111-1130. (M8) Gocan, S.; Panea, I.; Anechitei, I. Stud. Univ. Babes-Bolyai, Chem. 1990, 35, 54-58; Chem. Abstr. 1994, 120, 56646d. (M9) Ganz, J.; Jork, H. J. Planar Chromatogr.-Mod. TLC 1994, 7, 18-21.

(M10) Peischl, R. J.; Sabo, M.; Dugan, G. E.; Puerschner, G. J. Planar Chromatogr.-Mod. TLC 1994, 7, 211-216. (M11) Varshney, K. M.; Jettappa, T.; Mehrotra, V. K.; Baggi, T. R. Forensic Sci. Int. 1995, 72, 107-115. (M12) Aginsky, V. N. J. Chromatogr., A 1994, 678, 119-125. (M13) Schiedt, K. Carotenoids 1995, 1A, 131-144. (M14) Lai, C.-K.; Lam, C.-W.; Chan, Y.-W. Clin. Chem. (Washington, D.C.) 1994, 40, 2026-2029. (M15) Cserhati, T.; Forgacs, E.; Hollo, J. J. Planar Chromatogr.-Mod. TLC 1993, 6, 472-475. (M16) Rosas, R. A. J.; Herrera, J. C.; Martinez De Aparicio, E.; Molina Cuevas, E. A. J. Chromatogr., A 1994, 667, 361-366. (M17) Johjima, T. Engei Gakkai Zasshi 1993, 62, 567-574; Chem. Abstr. 1994, 120, 211707v. (M18) Bartolome, E. R. J. Planar Chromatogr.-Mod. TLC 1994, 7, 70-72. (M19) Ficarra, P.; Ficarra, R.; Costantino, D.; Carulli, M.; Tommasini, S.; De Pasquale, A.; Calabro, M. L. Boll. Chim. Farm. 1994, 133, 221-227; Chem. Abstr. 1994, 121, 244940q. (M20) Burton, D. E.; Bailey, D. L.; Lillie, C. H. J. Planar Chromatogr.Mod. TLC 1993, 6, 223-227. (M21) Hadj-Mahammed, M.; Meklati, B. Y. J. Planar Chromatogr.Mod. TLC 1993, 6, 242-244. (M22) Nikolova-Damyanova, B.; Ilieva, E.; Handjieva, N.; Bankova, V. Phytochem. Anal. 1994, 5, 38-40. (M23) Krawczyk, U.; Petri, G.; Kery, A. Acta Pol. Pharm. 1993, 50, 317-319.

(O22) Alvarez, J. C.; Slomovic, B.; Ludmir, J. J. Chromatogr., B: Biomed. Appl. 1995, 665, 79-87. (O23) Schuerer, N. Y.; Schliep, V.; Barlag, K. Exp. Dermatol. 1995, 4, 46-51. (O24) Lin, L.; Zhang, J.; Huang, S.; He, C.; Tang, J. J. Planar Chromatogr.-Mod. TLC 1994, 7, 25-28. (O25) Wiesner, D. A.; Sweeley, C. C. Anal. Chim. Acta 1995, 311, 57-62. (O26) Davani, B.; Olsson, N. U. J. Planar Chromatogr.-Mod. TLC 1995, 8, 33-35. (O27) Smith, M. C.; Webster, C. L.; Sherma, J.; Fried, B. J. Liq. Chromatogr. 1995, 18, 527-535. (O28) Vecchini, A.; Chiaradia, E.; Covalovo, S.; Binaglia, L. Mol. Cell. Biochem. 1995, 145, 25-28. (O29) Tvrzicka, E.; Votruba, M. Chromatogr. Sci. Ser. 1994, 65, 5173. (O30) St. Angelo, A. J.; James, C., Jr. J. Am. Oil Chem. Soc. 1993, 70, 1245-1250. (O31) Przybylski, R.; Eskin, N. A. M. Food Chem. 1994, 51, 231235. (O32) Dunstan, G. A.; Volkman, J. K.; Barrett, S. M. Lipids 1993, 28, 937-944. (O33) Gerin, C.; Goutx, M. J. Planar Chromatogr.-Mod. TLC 1993, 6, 307-312. (O34) Marquez-Ruiz, G.; Perez-Camino, M. C.; Dobarganes, M. C. J. Chromatogr. 1994, 662, 363-368. Pesticides

Hydrocarbons (N1) Tyrpien, K. J. Planar Chromatogr.-Mod. TLC 1993, 6, 413415. (N2) Moeller, K.; Sieber, M. GIT Spez. Chromatogr. 1994, 14, 8184; Chem. Abstr. 1995, 123, 178909z. (N3) Dhole, V. R.; Ghosal, G. K. J. Planar Chromatogr.-Mod. TLC 1994, 7, 469-471. (N4) Dhole, V. R.; Ghosal, G. K. J. Planar Chromatogr.-Mod. TLC 1995, 8, 80-81. (N5) Baranowska, I.; Szeja, W.; Wasilewski, P. J. Planar Chromatogr.Mod. TLC 1994, 7, 137-141. (N6) Asaumi, M.; Shirai, K.; Venkateswaran, K. J. Mar. Biotechnol. 1994, 2, 45-50. (N7) Cavanagh, J.-A. E.; Juhasz, A. L.; Nichols, P. D.; Franzmann, P. D.; McMeekin, T. A. J. Microbiol. Methods 1995, 22, 119130. (N8) Friedbacher, E. C.; Schindbauer, H. Bitumin 1994, 56, 105108. (N9) Friedbacher, E. C.; Schindbauer, H. Bitumin 1993, 55, 149151. (N10) Vela, J.; Cebolla, V. L.; Membrado, L.; Andres, J. M. J. Chromatogr. Sci. 1995, 33, 417-425. Lipids (O1) Wardas, W.; Pyka, A. J. Planar Chromatogr.-Mod. TLC 1993, 6, 320-322. (O2) Wardas, W.; Jedrzejczyk, M. Chem. Anal. (Warsaw) 1995, 40, 73-79. (O3) Wardas, W.; Pyka, A. J. Planar Chromatogr.-Mod. TLC 1994, 7, 440-443. (O4) Sagami, H.; Kurisaki, A.; Ogura, K.; Chojnacki, T. J. Lipid Res. 1992, 33, 1857-1861. (O5) Bonte, F.; Pinguet, P.; Chevalier, J. M.; Meybeck, A. J. Chromatogr., B: Biomed. Appl. 1995, 664, 311-316. (O6) Sajbidor, J.; Certik, M.; Grego, J. J. Chromatogr., A 1994, 665, 191-195. (O7) Nikolova-Damyanova, B.; Christie, W. W.; Herslof, B. J. Planar Chromatogr.-Mod. TLC 1994, 7, 382-385. (O8) Martinez-Lorenzo, M. J.; Marzo, I.; Naval, J.; Piniero, A. Anal. Biochem. 1994, 220, 210-212. (O9) Nikolova-Damyanova, B.; Chobanov, D.; Dimov, S. J. Liq. Chromatogr. 1993, 16, 3997-4008. (O10) Tarandjiiska, R.; Marekov, I.; Nikolova-Damyanova, B.; Amidzhin, B. J. Liq. Chromatogr. 1995, 18, 859-872. (O11) Hamid, M. E.; Minnikin, D. E.; Goodfellow, M.; Ridell, M. Zentralbl. Bakteriol. 1993, 279, 354-367. (O12) Schnaar, R. L.; Needham, L. K. Methods Enzymol. 1994, 230, 371-389. (O13) Watanabe, K.; Mizuta, M. J. Lipid Res. 1995, 36, 1848-1855. (O14) Ogawa-Goto, K.; Ohta, Y.; Kubota, K.; Funamoto, N.; Abe, T.; Taki, T.; Nagashima, K. J. Neurochem. 1993, 61, 1398-1403. (O15) Taki, T.; Handa, S.; Ishikawa, D. Anal. Biochem. 1994, 223, 232-238. (O16) Muething, J. J. Chromatogr., B: Biomed. Appl. 1994, 657, 7581. (O17) Arnsmeier, S. L.; Paller, A. S. J. Lipid Res. 1995, 36, 911915. (O18) Cartwright, I. J. Methods Mol. Biol. (Totowa, N.J.) 1993, 19, 153-167. (O19) Perez, M. K.; Fried, B.; Sherma, J. J. Planar Chromatogr.-Mod. TLC 1994, 7, 340-343. (O20) Linard, A.; Guesnet, P.; Durand, G. J. Planar Chromatogr.-Mod. TLC 1993, 6, 322-323. (O21) Brailoiu, E.; Saila, L.; Huhurez, G.; Costuleanu, M.; Filipeanu, C. M.; Slatineau, S.; Cotutz, C.; Branisteanu, D. D. Biomed. Chromatogr. 1994, 8, 193-195.

(P1) Sherma, J. J. Planar Chromatogr.-Mod. TLC 1994, 7, 265272. (P2) Wang, Q. S.; Yan, B. W.; Zhang, L. Chromatographia 1995, 40, 463-466. (P3) Darwish, Y.; Cserhati, T.; Forgacs, E. Chromatographia 1994, 38, 509-513. (P4) Reuke, S.; Hauck, H. E. Fresenius’ J. Anal. Chem. 1995, 351, 739-744. (P5) Pfaab, G.; Jork, H. Acta Hydrochim. Hydrobiol. 1994, 22, 216223. (P6) Burger, K. Chem. Plant Prot. 1995, 12, 181-195. (P7) Stan, H.-J.; Butz, S. Chem. Plant Prot. 1995, 12, 197-216. (P8) Butz, S.; Stan, H.-J. Anal. Chem. 1995, 67, 620-630. (P9) Mali, B. D.; Garad, M. V.; Patil, V. B.; Padalikar, S. V. J. Chromatogr., A 1995, 704, 540-543. (P10) Bose, D.; Shivhare, P.; Gupta, V. K. J. Planar Chromatogr.-Mod. TLC 1994, 7, 415-418. (P11) Leuenberger, U.; Gauch, R.; Rieder, K.; Mueller, U. Mitt. Geb. Lebensmittelunters. Hyg. 1994, 85, 669-680; Chem. Abstr. 1995, 123, 54380a. (P12) Patil, V. B.; Shingare, M. S. Talanta 1994, 41, 2127-2130. (P13) Falah, I. I.; Hammers, W. E. Toxicol. Environ. Chem. 1994, 42, 35-49. (P14) Zayed, S. M. A. D.; Mostafa, I. Y.; El-Arab, A. E. J. Environ. Sci. Health, Part B 1994, B29, 169-175. (P15) Jablonkai, I.; Hatzios, K. K. Pestic. Biochem. Physiol. 1994, 48, 98-109. (P16) Guerrini, P.; Vilarem, G.; Gaset, A. J. Planar Chromatogr.-Mod. TLC 1995, 8, 194-199. (P17) Johnson, R. M.; Pepperman, A. B. J. Liq. Chromatogr. 1995, 18, 739-753. (P18) Zahradnickova, H.; Simek, P.; Horicova, P.; Triska, J. J. Chromatogr., A 1994, 688, 383-389. (P19) Sherma, J.; McGinnis, S. C. J. Liq. Chromatogr. 1995, 18, 755761. Pharmaceuticals, Drugs, and Alkaloids (Q1) Kovacs-Hadady, K. J. Planar Chromatogr.-Mod. TLC 1995, 8, 47-51. (Q2) Tivert, A. M.; Backman, A. J. Planar Chromatogr.-Mod. TLC 1993, 6, 216-219. (Q3) Bieganowska, M. L.; Petruczynik, A. Chem. Anal. (Warsaw) 1994, 39, 139-147. (Q4) Munro, Ch; White, Pc Sci. Justice 1995, 35, 37-44. (Q5) Patil, V. B.; Shingare, M. S. J. Planar Chromatogr.-Mod. TLC 1993, 6, 497-498. (Q6) Lillsunde, P.; Korte, T. In Analysis of Addictive and Misused Drugs; Adamovics, J. A., Ed.; Dekker: New York, 1995; pp 221-265. (Q7) Schuetz, H.; Rochholz, G.; Seno, H.; Weiler, G. Pharmazie 1994, 49, 213-216; Chem. Abstr. 1994, 120, 289249s. (Q8) Brunk, S. D. In Analysis of Addictive and Misused Drugs; Adamovics, J. A., Ed.; Dekker: New York, 1995; pp 41-50. (Q9) de Zeeuw, R. A.; Franke, J. P.; van Halem, M.; Schaapman, S.; Logawa, E.; Siregar, C. J. P. J. Anal. Toxicol. 1994, 18, 402406. (Q10) de Zeeuw, R. A.; Francke, J. P.; van Halem, M.; Schaapman, S.; Logawa, E.; Siregar, C. J. P. J. Chromatogr., A 1994, 664, 263-270. (Q11) Rochholz, G.; Ahrens, B.; Schuetz, H. Arzneim.-Forsch. 1994, 44, 469-471. (Q12) Jain, R. Indian J. Pharmacol. 1993, 25, 240-242. (Q13) Dietzen, D. J.; Koenig, J.; Turk, J. J. Anal. Toxicol. 1995, 19, 299-303. (Q14) Kenyon, A. S.; Flinn, P. E.; Layloff, T. P. J. AOAC Int. 1995, 78, 41-49.


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(Q15) Shearan, P.; O’Keeffe, M. Analyst (Cambridge, U.K.) 1994, 119, 2761-2764. (Q16) Pachaly, P. Dtsch. Apoth. Ztg. 1993, 133, 15-16, 19-21; Chem. Abstr. 1994, 121, 238490b. (Q17) Parvais, O.; Vander Stricht, B.; Vanhaelen-Fastre, R.; Vanhaelen, M. J. Planar Chromatogr.-Mod. TLC 1994, 7, 80-82. (Q18) Romano, G.; Caruso, G.; Musumarra, G.; Pavone, D.; Cruciani, G. J. Planar Chromatogr.-Mod. TLC 1994, 7, 233-241. (Q19) Bailey, D. N. Am. J. Clin. Pathol. 1994, 101, 342-345. (Q20) Heinisch, G.; Kopelent-Frank, H.; Nixdorf, C. Sci. Pharm. 1993, 61, 251-264; Chem. Abstr. 1995, 122, 38975x. (Q21) Medina, M. B.; Unruh, J. J.; Jones, E.; Bueso, C. E. Residues Vet. Drugs Food, Proc. EuroResidue Conf., 2nd 1993, 2, 490494; Chem. Abstr. 1994, 121, 156018q. (Q22) Misztal, G.; Gumieniczek, A. Acta Pol. Pharm. 1994, 51, 215218. (Q23) Otsubo, K.; Seto, H.; Futagami, K.; Oishi, R. J. Chromatogr., B: Biomed. Appl. 1995, 669, 408-412. (Q24) Pachaly, P.; Schick, W. Pharm. Ind. 1993, 55, 259-267; Chem. Abstr. 1994, 120, 15001w. (Q25) Tombesi, O. L.; Maldoni, B. E.; Bartolome, E. R.; Haurie, H. M.; Faraoni, M. B. J. Planar Chromatogr.-Mod. TLC 1994, 7, 77-79. (Q26) Taylor, W. G.; Danielson, T. J.; Orcutt, R. L. J. Chromatogr., B: Biomed. Appl. 1994, 661, 327-333. (Q27) Chauhan, B. L.; Mitra, S. K.; Mohan, A. R.; Gopumadhavan, S.; Anturlikar, S. D. Indian Drugs 1994, 31, 333-338. (Q28) Marciniec, B.; Kujawa, E.; Ogrodowczyk, M. Pharmazie 1992, 47, 502-504. (Q29) Parimoo, P.; Bharathi, A.; Shajahan, M. Indian Drugs 1994, 31, 139-143. (Q30) Sanyal, A. K.; Chowdhury, B.; Banerjee, A. B. J. AOAC Int. 1993, 76, 1152-1155. (Q31) Zarapkar, S. S.; Dhanvate, A. A.; Soshi, V. J.; Salunkhe, U. B.; Sawant, S. V. Indian Drugs 1994, 31, 468-471. (Q32) Jindal, K. C.; Chaudhary, R. S.; Gangwal, S. S.; Singla, A. K.; Khanna, S. J. Chromatogr., A 1994, 685, 195-199. (Q33) Shirke, P. P.; Patel, M. K.; Tamhane, V. A.; Tirodkar, V. B.; Sethi, P. D. East. Pharm. 1994, 37, 155-156; Chem. Abstr. 1995, 123, 266276w. (Q34) Shirke, P. P.; Patel, M. K.; Tamhane, V. A.; Tirodkar, V. B.; Sethi, P. D. East. Pharm. 1994, 37, 179-180; Chem. Abstr. 1995, 123, 266285y. (Q35) Aboul-Enein, H. Y.; Serignese, V. Anal. Lett. 1994. 27, 723729. (Q36) Alemany, G.; Gamundi, A.; Nicolau, M. C.; Saro, D. Biomed. Chromatogr. 1993, 7, 273-274. (Q37) Argekar, A. P.; Raj, S. V.; Kapadia, S. U. Indian Drugs 1995, 32, 166-171. (Q38) Capote, R.; Francisco, G.; Gonzalez, J. A.; Nunez, A. J. J. Planar Chromatogr.-Mod. TLC 1995, 8, 155-156. (Q39) Cenni, B.; Betschart, B. J. Planar Chromatogr.-Mod. TLC 1994, 7, 294-296. (Q40) Chandrashekhar, T. G.; Rao, P. S. N.; Smrita, K.; Vyas, S. K.; Dutt, C. J. Planar Chromatogr.-Mod. TLC 1994, 7, 458-460. (Q41) Chandrashekhar, T. G.; Rao, P. S. N.; Sneth, D.; Vyas, S. K.; Dutt, C. J. Planar Chromatogr.-Mod. TLC 1994, 7, 249-250. (Q42) Dammertz, W.; Paulus, H. J. Planar Chromatogr.-Mod. TLC 1995, 8, 314-318. (Q43) El-Bardicy, M. G.; El-Gendy, A. E.; Loutfy, H. M.; Ellaithy, M. M. Bull. Fac. Pharm. (Cairo Univ.) 1993, 31, 291-296; Chem. Abstr. 1995, 122, 197122h. (Q44) Farina, A.; Doldo, A.; Cotichini, V.; Gallo, F. R.; Calandra, S. J. Planar Chromatogr.-Mod. TLC 1994, 7, 386-388. (Q45) Farina, A.; Quaglia, M. G.; Doldo, A.; Calandra, S.; Gallo, F. R. J. Pharm. Biomed. Anal. 1993, 11, 1215-1218. (Q46) Fijalek, Z.; Snycerski, A. Acta Pol. Pharm. 1993, 50, 301306. (Q47) Guilleux, J.-C.; Barnouin, K. N.; Lerner, D. A. Anal. Chim. Acta 1994, 292, 141-149. (Q48) Gyulemetova, R.; Zdravcheva, D.; Pangarova, T. J. Planar Chromatogr.-Mod. TLC 1995, 8, 241-242. (Q49) Kaniou, I.; Zachariadis, G.; Kalligas, G.; Tsoukali, H.; Stratis, J. J. Liq. Chromatogr. 1994, 17, 1385-1398. (Q50) Khan, K.; Paesen, J.; Roets, E.; Hoogmartens, J. J. Planar Chromatogr.-Mod. TLC 1994, 7, 349-353. (Q51) Koch, A. Dtsch. Apoth. Ztg. 1993, 133, 26, 29-30, 35; Chem. Abstr. 1994, 121, 164084y. (Q52) Kockar, O. M.; Kara, M.; Kara, S.; Bozan, B.; Baser, K. H. C. Fitoterapia 1994, 65, 439-443; Chem. Abstr. 1995, 122, 170314k. (Q53) Konfino, M.; Deltcheva, S.; Mindjova, K. J. Planar Chromatogr.Mod. TLC 1993, 6, 404-406. (Q54) Martin, E.; Duret, M.; Vogel, J. Mitt. Geb. Lebensmittelunters. Hyg. 1993, 84, 274-280; Chem. Abstr. 1994, 121, 203609v. (Q55) Matysik, G.; Toczolowski, J.; Matysik, A. Chromatographia 1995, 40, 737-739. (Q56) McLaughlin, J. R.; Sherma, J. J. Planar Chromatogr.-Mod. TLC 1991, 4, 492-493. (Q57) Mody, V. D.; Patel, R. B.; Chakravarthy, B. J. Planar Chromatogr.-Mod. TLC 1994, 7, 164-165. (Q58) Paesen, J.; Quintens, I.; Thoithi, G.; Roets, E.; Reybrouck, G.; Hoogmartens, J. J. Chromatogr., A 1994, 677, 377-384. (Q59) Ponder, G. W.; Stewart, J. T. J. Chromatogr. 1994, 659, 177183. (Q60) Ray, S.; De, P. K. Indian Drugs 1994, 31, 543-547. 18R


(Q61) Rossini, C.; Pandolfi, E.; Dellacassa, E.; Moyna, P. J. AOAC Int. 1995, 78, 115-117. (Q62) Sanghavi, N. M.; Puranik, K. A.; Samarth, M. M. Indian Drugs 1995, 32, 53-54. (Q63) Shinde, V. M.; Desai, B. S.; Tendolkar, N. M. Indian Drugs 1994, 31, 119-121. (Q64) Shinde, V. M.; Desai, B. S.; Tendolkar, N. M. Indian Drugs 1994, 31, 192-196. (Q65) Shinde, V. M.; Tendolkar, N. M.; Desai, B. S. J. Planar Chromatogr.-Mod. TLC 1994, 7, 133-136. (Q66) Shinde, V. M.; Tendolkar, N. M.; Desai, B. S. J. Planar Chromatogr.-Mod. TLC 1994, 7, 50-53. (Q67) Shirke, P. P.; Patel, M. K.; Tamhane, V. A.; Tirodkar, V. B.; Sethi, P. D. Indian Drugs 1993, 30, 653-654. (Q68) Shirke, P. P.; Patel, M. K.; Tamhane, V.; Sethi, P. D. Indian J. Pharm. Sci. 1994, 56, 108-109. (Q69) Smith, M. C.; Sherma, J. J. Planar Chromatogr.-Mod. TLC 1995, 8, 14-16. (Q70) Spell, J. C.; Stewart, J. T. J. Planar Chromatogr.-Mod. TLC 1995, 8, 72-74. (Q71) Spell, J. C.; Stewart, J. T. J. Planar Chromatogr.-Mod. TLC 1994, 7, 472-473. (Q72) Tam, M. N.; Nikolova-Damyanova, B.; Pyuskyulev, B. J. Liq. Chromatogr. 1995, 18, 849-858. (Q73) Tammilehto, S.; Salomies, H.; Torniainen, K. J. Planar Chromatogr.-Mod. TLC 1994, 7, 368-371. (Q74) Taylor, M. R.; Westwood, S. A. J. Planar Chromatogr.-Mod. TLC 1993, 6, 415-418, (Q75) Tendolkar, N. M.; Desai, B. S.; Gaudh, J. S.; Shinde, V. M. Anal. Lett. 1995, 28, 1641-1653. (Q76) Tuszynska, E.; Podolska, M.; Kwiatkowska-Puchniarz, B.; Kaniewska, T. Acta Pol. Pharm. 1994, 51, 317-323. (Q77) Ferreira, F.; Moyna, P.; Soule, S.; Vazquez, A. J. Chromatogr. 1993, 653, 380-384. (Q78) Sun, S. W.; Fabre, H. J. Liq. Chromatogr. 1994, 17, 433-445. (Q79) Sun, S. W.; Fabre, H.; Maillols, H. J. Liq. Chromatogr. 1994, 17, 2495-2509. (Q80) Renger, B.; Jehle, H.; Fischer, M.; Funk, W. J. Planar Chromatogr.-Mod. TLC 1995, 8, 269-278. (Q81) Ferenczi-Fodor, K.; Vegh, Z. J. Planar Chromatogr.-Mod. TLC 1993, 6, 256-258. (Q82) Szepesi, G. J. Planar Chromatogr.-Mod. TLC 1993, 6, 259268. (Q83) Sosa, M. E.; Valdes, J. R.; Martinez, J. A. J. Chromatogr. 1994, 662, 251-254. (Q84) Lemire, S. W.; Busch, K. L. J. Planar Chromatogr.-Mod. TLC 1994, 7, 221-228. Purines, Pyrimidines, and Nucleic Acids (R1) Keith, G. Biochimie 1995, 77, 142-144. (R2) Srinivas, B.; Srinivasulu, K. J. Indian Chem. Soc. 1994, 71, 711-712. (R3) Foersti, A.; Staffas, J.; Hemminki, K. Carcinogenesis 1994, 15, 2829-2834. (R4) Savela, K.; Hemminki, K. Environ. Health Perspect. 1993, 101, 145-150. (R5) Turteltaub, K. W.; Vogel, J. S.; Frantz, C. E.; Fultz, E. IARC Sci. Publ. 1993, 124, 293-301. Steroids (S1) Rivas-Nass, A.; Muellner, S. J. Planar Chromatogr.-Mod. TLC 1994, 7, 278-285. (S2) Srinivas, B.; Srinivasulu, K. J. Indian Chem. 1993, 70, 853854. (S3) Vegh, Z. J. Planar Chromatogr.-Mod. TLC 1993, 6, 228-231. (S4) Agrawal, A. K.; Pampori, N. A.; Shapiro, B. H. Anal. Biochem. 1995, 224, 455-457. (S5) Daeseleire, E.; Vanoosthuyze, K.; Van Peteghem, C. J. Chromatogr., A 1994, 674, 247-253. (S6) Hoebus, J.; Daneels, E.; Roets, E.; Hoogmartens, J. J. Planar Chromatogr.-Mod. TLC 1993, 6, 269-273. (S7) Datta, K.; Das, S. K. J. AOAC Int. 1994, 77, 1453-1458. Surfactants (T1) McPherson, B. P.; Rasmussen, H. T. Surfactant Sci. Ser. 1994, 53, 289-326. (T2) Cserhati, T. J. Biochem. Biophys. Methods 1993, 27, 133-142. (T3) Kruse, A.; Buschmann, N.; Cammann, K. J. Planar Chromatogr.Mod. TLC 1994, 7, 22-24. (T4) Buergi, Ch.; Otz, T. Tenside, Surfactants, Deterg. 1995, 32, 22-24. (T5) Buschmann, N.; Wodarczak, S. Comun. Jorn. Com. Esp. Deterg. 1994, 25, 203-207. (T6) Yang, J.; Zhang, L.; Li, X. J. Am. Oil Chem. Soc. 1994, 71, 109-111. Toxins (U1) Nawaz, S.; Coker, R. D.; Haswell, S. J. J. Planar Chromatogr.Mod. TLC 1995, 8, 4-9. (U2) Horwitz, W.; Albert, R.; Nesheim, S. J. AOAC Int. 1993, 76, 461-491.

(U3) Park, D. L.; Trucksess, M. W.; Nesheim, S.; Stack, M.; Newell, R. F. J. AOAC Int. 1994, 77, 637-646. (U4) Diaz, S.; Dominguez, L.; Prieta, J.; Blanco, J. L.; Moreno, M. A. J. Agric. Food Chem. 1995, 43, 2678-2680. (U5) Bradburn, N.; Coker, R. D.; Blunden, G. Food Chem. 1994, 52, 179-185. (U6) Dupuy, J.; Le Bars, P.; Le Bars, J.; Boudra, H. J. Planar Chromatogr.-Mod. TLC 1993, 6, 476-480. (U7) Shelby, R. A.; Rottinghaus, G. E.; Minor, H. C. J. Agric. Food Chem. 1994, 42, 2064-2067. (U8) Mallmann, C. A.; Santurio, J. M.; Baldissera, M. A.; von Mickwitz, G. Rev. Microbiol. 1994, 25, 107-111. (U9) Fernandez, C.; Stack, M. E.; Musser, S. M. J. AOAC Int. 1994, 77, 628-630. (U10) Ojanperae, I.; Pelander, A.; Vuori, E.; Himberg, K.; Waris, M.; Niinivaara, K. J. Planar Chromatogr.-Mod. TLC 1995, 8, 6972. Vitamins (V1) Wardas, W.; Pyka, A. Chem. Anal. (Warsaw) 1995, 40, 6772. (V2) Sliwiok, J.; Kocjan, B.; Labe, B.; Kozera, A.; Zalejska, J. J. Planar Chromatogr.-Mod. TLC 1993, 6, 492-494. (V3) Bargagna, A.; Mariani, E.; Dorato, S. Acta Technol. Legis Med. 1991, 2, 75-86; Chem. Abstr. 1994, 120, 280385a. (V4) Bhushan, R.; Parshad, V. Biomed. Chromatogr. 1994, 8, 196198. (V5) Madden, U. A.; Stahr, H. M. J. Liq. Chromatogr. 1993, 16, 2825-2834. (V6) Navas Diaz, A.; Guirado Paniagua, A.; Garcia Sanchez, F. J. Chromatogr. 1993, 655, 39-43. Miscellaneous Organic Compounds (W1) Poole, S. K.; Poole, C. F. Analyst (Cambridge, U.K.) 1994, 119, 113-120. (W2) Petrovic, S. M.; Loncar, E.; Perisic-Janjic, N. U. Chromatographia 1994, 38, 744-748. (W3) Perisic-Janjic, N. U.; Djakovic, T. Lj.; Petrovic, S. M. Chromatographia 1995, 40, 96-98. (W4) Ng, K. G.; Price, K. R.; Fenwick, G. R. Food Chem. 1994, 49, 311-315. (W5) Quirk, R. P.; Kuang, J. Polym. Int. 1994, 33, 181-186. (W6) Gutorska, A.; Helbrecht, A. J. Planar Chromatogr.-Mod. TLC 1995, 8, 36-38. (W7) Bartels, R.; Bock, L. J. Chromatogr. 1994, 659, 185-189. (W8) Demirezer, L. O. Pharmazie 1994, 49, 936-937. (W9) Danielsen, K.; Francis, G. W. Chromatographia 1994, 38, 520. (W10) Baranowska, I.; Maslinska-Solich, J.; Swierczek, S. Acta Chromatogr. 1993, 2, 56-64. (W11) Bratt, C. E.; Akerlund, H.-E. Plant Physiol. Biochem. (Paris) 1994, 32, 313-315. (W12) Tusarova, I.; Halamek, E.; Kobliha, Z. J. Planar Chromatogr.Mod. TLC 1994, 7, 372-375. (W13) Upadhyay, R. K.; Sharma, R. K.; Babu, G.; Mishra, (Km.) G. J. Planar Chromatogr.-Mod. TLC 1994, 7, 464-468. (W14) Zitko, V. Chemosphere 1994, 28, 1211-1215. (W15) Rozylo, J. K. J. Planar Chromatogr.-Mod. TLC 1993, 6, 467471. (W16) Sohr, J.; Janes, W.; Bongartz, A. Analusis 1995, 23, M25M26. (W17) Mazurek, M.; Witkiewicz, Z. Chem. Anal. (Warsaw) 1994, 40, 531-542. (W18) Steuckart, C.; Berger-Preiss, E.; Levsen, K. Anal. Chem. 1994, 66, 2570-2577.

(W19) Zou, H.; Zhou, S.; Hu, X.; Zhang, Y.; Lu, P. J. Planar Chromatogr.-Mod. TLC 1994, 7, 461-463. (W20) Echterhoff, A. M.; Petz, M. Dtsch. Lebensm.-Rundsch. 1994, 90, 341-344; Chem. Abstr. 1995, 123, 31512f. (W21) Bladek, J.; Miszczak, M. Adv. Anal. Detect. Explos., Proc. Int. Symp., 4th 1992 1993, 199-207; Chem. Abstr. 1994, 120, 221769f. (W22) Kiridena, W.; Miller, K. G.; Poole, C. F. J. Planar Chromatogr.Mod. TLC 1995, 8, 177-183. (W23) Kiridena, W.; Poole, S. K.; Poole, C. F. J. Planar Chromatogr.Mod. TLC 1994, 7, 273-277. (W24) Di, X.; Wu, W.; Sun, Y.; Hu, Y. Sepu 1994, 12, 173-174; Chem. Abstr. 1994, 121, 164095c. (W25) Barthomeuf, C.; Chmielowiec, C.; Pourrat, H. J. Planar Chromatogr.-Mod. TLC 1994, 7, 474-476. (W26) Belay, M. T.; Poole, C. F. Chromatographia 1993, 37, 365373. (W27) Poole, S. K.; Kiridena, W.; Miller, K. G.; Poole, C. F. J. Planar Chromatogr.-Mod. TLC 1995, 8, 257-268. Inorganics and Metal Organics (X1) Mohammad, A.; Khan, M. A. M. Chem. Environ. Res. 1992, 1, 3-31. (X2) Mohammad, A.; Fatima, N.; Ahmad, J.; Khan, M. A. M. J. Chromatogr. 1993, 642, 445-453. (X3) Kumar, M. Analyst (Cambridge, U.K.) 1994, 119, 2013-2024. (X4) Ahmad, J. Sep. Sci. Technol. 1995, 30, 2429-2454. (X5) Yadev, S. K.; Singh, O. V.; Tandon, S. N. J. Planar Chromatogr.Mod. TLC 1994, 7, 75-77. (X6) Takeda, Y.; Nagai, T.; Ishida, K. Fresenius’ J. Anal. Chem. 1995, 351, 186-189. (X7) Shimizu, T.; Kaneko, M.; Toyoshima, Y. J. Planar Chromatogr.Mod. TLC 1995, 8, 152-154. (X8) Shimizu, T.; Jindo, S.; Satoh, M.; Mura, Y. J. Planar Chromatogr.-Mod. TLC 1994, 7, 412-415. (X9) Shimizu, T.; Jindo, S.; Iwata, N.; Tamura, Y. J. Planar Chromatogr.-Mod. TLC 1994, 7, 98-102. (X10) Nabi, S. A.; Farooqui, W. U.; Rahman, N. J. Planar Chromatogr.Mod. TLC 1994, 7, 38-40. (X11) Mohammad, A.; Khan, M. A. M. J. Planar Chromatogr.-Mod. TLC 1995, 8, 134-140. (X12) Mohammad, A.; Khan, M. A. M. J. J. Chromatogr. Sci. 1995, 33, 531-535. (X13) Mohammad, A.; Ajmal, M.; Fatima, N.; Yousuf, R. J. Planar Chromatogr.-Mod. TLC 1994, 7, 444-449. (X14) Anwar, J.; Mahmud, T.; Bhatti, T. Sci. Int. (Lahore) 1993, 5, 19-20; Chem. Abstr. 1994, 120, 44644p. (X15) Gupta, V. K.; Ali, I.; Khurana, U.; Dhagarra, N. J. Liq. Chromatogr. 1995, 18, 1671-1681. (X16) Sharma, S. D.; Misra, S.; Agrawal, R. J. Chromatogr. Sci. 1995, 33, 463-466. (X17) Celap, M. B. Conf. Coord. Chem. 1993, 14th, 51-52; Chem. Abstr. 1994, 120, 314570z. (X18) Janjic, T. J.; Zivkovic, V.; Celap, M. B. Chromatographia 1994, 38, 447-452. (X19) Martinez, B.; Orte, J. C.; Miro, M.; Crovetto, G.; Thomas. J. J. Chromatogr. 1993, 655, 45-49. (X20) Vuckovic, G.; Miljevic, D.; Janjic, T. J.; Solujic, L.; Juranic, N. J. Serb. Chem. Soc. 1993, 58, 921-924; Chem. Abstr. 1995, 122, 204197s. (X21) Wenclawiak, B. W.; Flemming, M. J. High Resolut. Chromatogr. 1994, 17, 343-346.

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