UPCOMING RESEARCH Separation and Molecular Weight Distribution of Anionic and Cationic Water-Soluble Polymers by Flow Field-Flow Fractionation
Heuristic Evolving Latent Projection: Resolving Two-Way MulticomponentData. 1 . Selectivity, Latent-Projective Graph, Datascope, Local Rank, and Unique Resolution
Flow FFF is used to separate and characterize the molecular weight distribution and averages of anionic polystyrene sulfonate and cationic polyvinylpyridine. Phenomena associated with the separation are discussed. Maria Anna Benincasa and J. Calvin Giddings*, Field-Flow Fractionation Research Center, Department of Chemistry, University of Utah, Salt Lake City, UT 84112
A method called heuristic evolving latent projections (HELP) is developed for the resolution of two-way mixture data into pure spectra and concentration profiles. Olav M. Kvalheim* and Yi-zeng Liang, Department of Chemistry, University of Bergen, N-5007 Bergen, Norway
Determination of Selenium by Inductively Coupled Plasma Mass Spectrometry Utilizing a New Hydride Generation Sample Introduction System An inductively coupled plasma mass spectrometer with a newly designed continuous-flow hydride generator is used for the determination of Se in biological materials. Under optimum conditions a detection limit of 6.4 pg is achieved, whereas a detection limit of 1.3 ng is attained for routine analysis of 1-g samples of plant material. Wayne T. Buckley*, James J. Budac, and David V. Godfrey, Agriculture Canada Research Station, P.O. Box 1000, Agassiz, British Columbia, Canada VOM 1A0 and Karen M. Koenig, Department of Animal Science, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 Intravenous Microdialysis Sampling in Awake, Freely Moving Rats Intravenous microdialysis sampling in awake, freely moving rats is used to determine the pharmacokinetics of theophylline. Microdialysis sampling provides results t h a t are consistent with but not as perturbing to the system as whole blood sampling. Martin Telting-Diaz, Dennis O. Scott, and Craig E. Lunte*, Department of Chemistry, The University of Kansas, Lawrence, KS 66045 Determination of Amino Acids by Capillary Zone Electrophoresis Based on Semiconductor Laser Fluorescence Detection Amino acids are determined by indirect fluorometry and by labeling with a synthetic reagent t h a t is fluorescent in the red region. Second harmonic emission is used to detect amino acids labeled with a visible dye. Toshiyuki Higashijima, Tetsuhiro Fuchigami, Totaro Imasaka*, and Nobuhiko Ishibashi, Faculty of Engineering, Kyushu University, Hakozaki, Fukuoka 812, Japan
These articles are scheduled to appear in AC RESEARCH in the near future. *Corresponding author
Heuristic Evolving Latent Projection: Resolving Two-Way Multicomponent Data. 2. Detection and Resolution of Minor Constituents HELP resolves two-component isomer mixture data from an HPLC diode array detector system. Data are resolved down to at least 2% of the minor constituent and a chromatographic resolution of 0.2. Factor analysis reference methods fail to accomplish this task. Yi-zeng Liang and Olav M. Kvalheim'", Department of Chemistry, University of Bergen, N-5007 Bergen, Norway, Hans R. Keller and D. Luc Massart, Pharmaceutical Institute, Vrije Univesiteit Brussels, Laarbeeklaan 103, B-1090 Brussels, Belgium, and Peter Kiechle and Fritz Erni, Sandoz Pharma Ltd., CH-4002 Basel, Switzerland Rapid Functional Group Characterization of Gas Chromatography/Fourier Transform-Infrared Spectra by a Principal Components Analysis-Based Expert System A principal components analysis-based expert system is used to classify GC/FT-IR spectra into specific functional groups. This system shows more specificity than do selective wavelength chromatograms. Erik J. Hasenoehrl, Jonathan H. Perkins, and Peter R. Griffiths*, Department of Chemistry and Idaho Center for Hazardous Waste Remediation Research, University of Idaho, Moscow, ID 83843 Polymer Molecular Weight Distributions by Thermal Field-Flow Fractionation Using Mark-Houwink Constants Molecular weight distributions of polymers are measured by t h e r m a l F F F using calibrations determined with Mark-Houwink constants. The procedure uses concentration-dependent and viscometer detectors, connected in series. J. J. Kirkland* and S. W. Rementer, E. I. du Pont de Nemours and Co., Experimental Station, P.O. Box 80228, Wilmington, DE 19980-0228 Hartley/Hilbert Transform Spectroscopy: Absorption-Mode Resolution with Magnitude-Mode Precision Absorption and dispersion Fourier transform spectra are combined to enhance absorption spectra that are superior to conventional absorption, magnitude, a n d zero-filled absorption spectra. Christopher P. Williams and Alan G. Marshall*, Department of Biochemistry, 776 BioScience Building, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210 ANALYTICAL CHEMISTRY, VOL. 64, NO. 6, MARCH 15, 1992 · 373 A
UPCOMING RESEARCH Parts-per-Trillion Determination of Trihalomethanes in Water by Purge-and-Trap Gas Chromatography with Electron Capture Detection The detection limits are between 0.01 and 0.05 pptr, the linear dynamic range is up to 10,000 pptr, and the precision is better than or equal to ± 29c at 100 pptr. Louis Lépine* and Jean-François Archambault, Institut de Recherche d'Hydro-Québec, 1800 montée Sainte-Julie, Varennes, Québec, Canada J3X 1S1 Migration Behavior of Inorganic Anions in Micellar Electrokinetic Capillary Chromatography Using Cationic Surfactant Monovalent inorganic anions in cetyltrimethylammonium chloride solution migrate with a unique separation selectivity because of ion association with the surfactant and partitioning into the micelle. Takashi Kaneta, Shunitz Tanaka, Mitsuhiko Taga*, and Hitoshi Yoshida, Department of Chemistry, Faculty of Science, Hokkaido University, Kita-ku, Sapporo, 060, Japan Supercritical Carbon Dioxide Extraction of 2,4-Dichlorophenol from Food Crop Tissues Supercritical C 0 2 extraction with an acidic sample pretreatment is effective for the isolation of residues of 2,4dichlorophenol from food crop tissues. LC-EC detection limits are 0.06-0.18 ppm, and method precision is 1 0 20% RSD. Cynthia A. Thomson and David J. Chesney*, Department of Chemistry, Michigan Technological University, Houghton, MI 49931 Microscopic Order as a Function of Surface Coverage in Alkyl-Modified Silicas: Spin Probe Studies Increased microscopic order with increased grafting density for solvated octadecyl bonded silicas is established by the spin probe technique using dimethyloxazolidine-/Voxyl-cholestane. Paul B. Wright, Edward Lamb, John G. Dorsey, and Robert G. Kooser*, Department of Chemistry, Knox College, Galesburg, IL 61401 Selective Sorption and Column Concentration of Alkali-Metal Cations by Carboxylic Acid Resins with Dibenzo-14-crown-4 Subunits and Their Acyclic Polyether Analogues Good competitive sorption selectivity for Li + and Na + over other alkali-metal cations is observed for a dibenzo14-crown-4 resin in which the pendant carboxylic acid group is oriented over the polyether cavity. Takashi Hayashita, Joung Hae Lee, Matthew G. Hankins, Jong Chan Lee, Jong Seung Kim, John M. Knobeloch, and Richard A. Bartsch*, Department of Chemistry and Biochem istry, Texas Tech University, Lubbock, TX 79409-1061
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ANALYTICAL CHEMISTRY, VOL. 64, NO. 6, MARCH 15, 1992 · 375 A
