A C BRIEFS

compared with data from conventional volumetric procedures. .... of Virginia, Richmond, Va. ... recovery. The behavior of stable inorganic and organic...
2 downloads 0 Views 719KB Size
Download PDF
A C BRIEFS Highlights of Articles in This Issue

Basic and Practical Considerations in Utilizing Photon Counting for Quantitative Spectrochemical Methods The topics discussed include the effects of the photomultiplier tube and the measurement system on the signal and the reasons why a photon counting technique can lead to improved spectral resolution. A photon counting sys­ tem is described for use with the 1P28 photomultiplier tube. M. L. FRANKLIN, GARY HORLICK, and H. V. MALMSTADT, University of Illinois, Department of Chemistry and Chemial Engineering, Urbana, III. 61801 Anal. Chem. 41, 2 (1969) Nuclear Magnetic Resonance Study of the Thermal Decomposition of Ethylenedinitrilotetraacetic Acid and Its Salts in Aqueous Solutions By recording the proton spectra of the organic chelating agent, the rate of thermal decomposition of oxygen-free aqueous and deuterium oxide solutions containing eth­ ylenedinitrilotetraacetic acid, disodium cthylcnedinitrilotetraacetate, and tetralithium ethylenedinitrilotetraacetate was found. DAVID L. VENEZKY and WILLIAM B. MONIZ, Chemistry Division, Naval Research Laboratory, Washington, D. C. 20390 Anal. Chem. 41, 11 (1969) Computation of Channels Ratio in Liquid Scintillation Counting. A Theoretical Consideration The channels ratio is computed from two measurable parameters to determine if an approximate and optimal linear relationship with appropriate slope between the counting efficiency and channels ratio can be obtained for given instrument settings. C. T. PENG, Radioactivity Research Center and Depart­ ment of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco Medical Center, San Francisco, Calif. 94122 Anal. Chem. 41, 16 (1969)

Metastable Ion Characteristics. Measurements with a Modified Time-of-Flight Mass Spectrometer Included in this study are an instrument modification to defocus interfering normal ions and a computer method to calculate daughter ion masses. W. F. HADDON and F. W. McLAFFERTY, Department Chemistry, Purdue University, Lafayette, Ind. 47907

of

Anal. Chem. 41, 31 (1969) Resolution of Overlapping Bands: Simulating Band Shapes

Functions for

Expressions for symmetrical, skewed, and derivate bands are given and the types most suited to various analytical techniques are discussed. R. D. B. FRASER and EIKICHI SUZUKI, Division of Protein Chemistry, C.S.I.R.O., 343 Royal Parade, Parkville, Victoria 3052, Australia Anal. Chem. 41, 37 (1969) A Luminescence Method for the Determination of Iridium Iridium is determined by measuring the luminescence of the Ir(III)-[2,2',2"-terpyridine] chelate. This compound features high emission intensity and can be easily prepared in solution as a species of known stoichiometry. DAVID W. FINK AND WILLIAM E. OHNESORGE, Department of Chemistry, Lehigh University, Bethlehem, Pa. 18015 Anal. Chem. 41, 39 (1969) A Standardized Inert Dilution Method in X-Ray Fluorescence Analysis The method discussed is independent of the matrix sample and does not involve infinite dilutions, chemical compounds, or sample preparation for each element that is to be determined in the sample. RAFAEL VERA MEGE, Instituto Central de F'tsica, Universidad de Concepcion, Casilla 947, Concepcion, Chile Anal. Chem. 41, 42 (1969)

Computerized Learning Machines Applied to Chemical Problems. Molecular Formula Determination from Low Resolution Mass Spectrometry The method is applied to American Petroleum Institute Research Project 44 tables. Spectra were taken for com­ pounds in the range &-?, Ηι-ιο, Ο0-3, N0-= and included 150 CH, 138 CHO, 46 C H N , and 12 OHOH compounds. P. C. JURS, B. R. KOWALSKI, and T. L. ISENHOUR, De­ partment of Chemistry, University of Washington, Seattle, Wash. 98105 Anal. Chem. 41, 21 (1969)

Problems in Using Mossbauer Spectrometry for Quantitative Analysis: Application to Tin A series of synthetic stannic samples was used to measure the ness and sample concentration on parameters. The time stability analyzer was also studied.

oxide-aluminum oxide effecis of sample thickthe Mossbauer spectral of the single channel

P. A. PELLA, J. R. DeVOE, and D. K. SNEDIKER, National Bureau of Standards, Washington, D. C, and LEOPOLD MAY, Catholic University of America, Washington, D. C. Anal. Chem. 41, 46 (1969)

Determination by Neutron Activation Analysis of the Burn-Up Indicator Neodymium-148 in Irradiated Uranium Dioxide—Plutonium Dioxide Neodymium-148 is first isolated from all active and stable fission products by a 147 three-column separation procedure. A known amount of Nd tracer is then added to the sample and is irradiated. The 211 keV ' " N d peak is measured with a gamma ray spectrometer. M. R. MONSECOUR and A. C. DEMILDT, Studiecentrum voor Kernenergie, Centre d'Etude de l'Energie Nucléaire, Mol, Belgium Anal. Chem. 41, 27 (1969)

Analysis of Rare Earth Materials by Cathodoluminescence Spectra Excited in an Electron Microprobe The utility of the electron microprobe is extended by cathodoluminescence spectra for impurities, at concentration levels far below the detection limits of conventional X-ray techniques. Areas of less than 1 μ" to over 300 μ2 are examined. R. N. KNISELEY, FRANCIS C. LAABS, and VELMER A. FASSEL, Institute for Atomic Research and Department of Chemistry, Iowa State University, Ames, Iowa 50010 Anal. Chem. 41, 50 (1969) VOL. 4 1 , NO. 1, JANUARY 1969

·

11 A

AC

An Absorption Spectrometric Study of Molybdogermanic A c i d . M e t h o d s for t h e D e t e r m i n a t i o n of G e r m a n i u m

T h e r m o m e t r i c Titration Studies of Divalent Metal—Nitrilotriacetate Complexation Reactions

Nitrilotriacctic acid is titrated with concentrated solutions of divalent metal ions and the effects of p H are studied. The results are compared with a study of E D T A com­ plexation as a function of p H . F. E. FREEBERG, The Procter & Gamble Technical Center, Cincinnati, Ohio 45217

Co.,

BRIEFS

Ivorydale

Anal. Chem. 41, 54

(1969)

12-Molybdogermanic acid can be used for the direct ultra­ violet spectrophotometric determination of Ge either in aqueous or nonaqueous solution, the indirect ultraviolet spectrophotometric determination, and the indirect atomic absorption spectrometric determination of Ge. ROBERT JAKUBIEC and D. F. Chemistry, Wayne State University,

BOLTZ, Detroit,

Department Mich.

Anal. Chem. 41, 78

of (1969)

D e t e r m i n a t i o n of M e t a l l i c A l u m i n u m in H i g h Purity Aluminum Materials

Aluminum is determined by oxidation of the aluminumcontaining material in an acid solution of cerium (IV) sul­ fate followed by titration with sodium arsenite with Ferroin as indicator. RAYMOND S. LAMBERT, Hercules Incorporated, Bacchus Works, Magna, Utah 84044 Anal. Chem. 41, 57 (1969)

D e t e r m i n a t i o n of C o p p e r ( l l ) by C h e m i c a l S t r i p p i n g in A m m o n i a a n d Chloride Media

A simple, unpolished rotated platinum wire microelectrode is used for the determination of Cu(II) in complexing media where the reaction Cu° + Cu(II) —> 2 C u d ) is thcrmodynamically favorable. T. W. MALMGREN and J. W. BIXLER, Department of istry, Lake Forest College, Lake Forest, III. 60045

Chem­

Anal. Chem. 41, 61

(1969)

Distribution Coefficients and Effect of Chelating Agent in Removal of T r a c e M e t a l s f r o m U r e t h a n e by Zone Refining

if-values are measured for the removal of trace quantities of F e ( I I I ) and Mg(II) from urethane. The zone refining was performed in the absence and in the presence of 8quinolinol in order to study the effect of the chemical system on the separation. LOUIS N. JONES and BRUCE McDUFFIE, Department of Chemistry, State University of New York at Binghamton, Binghamton, Ν. Υ. 13901 Anal. Chem. 41, 65 (1969)

Solvent Extraction Separation of T a n t a l u m a n d N i o b i u m Fluorides with N-Benzoyl-N-Phenylhydroxylamine

Tantalum and niobium systems at various salt, acid, metal, fluoride, and BPHA concentrations define the extraction model over a wider fluoride concentration range and de­ termine optimum separation conditions.

A p p a r e n t Circular Dichroism of Oriented Systems

This paper examines the relationship between true and apparent circular dichroism spectra for an anisotropic uniaxial specimen having its optic axis perpendicular to the direction of the light beam. R. L. D/SCH and D. I. SVERCLIK, Department of Chemistry and Columbia Radiation Laboratory, Colombia University, New York, Ν. Υ. 10027 Anal. Chem. 41, 82 (1969)

Imidazole Catalysis of Organic Hydroxyl Group Determination by Reaction with Pyromellitic Dianhydride in D i m e t h y l f o r m a m i d e

Determination of alcohols by I M D A catalysis offers the advantages of a stable reagent solution, rapid reaction, instantaneous hydrolysis of excess P M D A , a colorless titration solution, a sharp visual end point, and excellent precision. β. Η. Μ. KINGSTON, J. J. GAREY, W. B. HELLWIG, Gen­ eral Electric, Silicone Products Department, Waterford, Ν. Υ. Anal. Chem. 41, 86 (1969)

Molecular Weight Determination of Polystyrene S t a n d a r d s by Vapor Pressure O s m o m e t r y

An extended range vapor pressure osmometer determines true number average molecular weights of polystyrene up to at least 400,000. The instrument detects temperature differences between a drop of solution and a drop of sol­ vent with a standard deviation of 3.5 X 10"° °C. ALFRED H. WACHTER and WILHELM of Organic Chemistry, Swiss Federal ogy (ΕΤΗ), 8006 Zurich, Switzerland

SIMON, Institute

of

Department Technol­

Anal. Chem. 41, 90

(1969)

J . S. ERSKINE, M. L. SINK, and L. P. VARGA, D e p a r t m e n t of Chemistry, Oklahoma State University, Stillwater, Okla. 74074 Anal. Chem. 41, 70 (1969) Column Efficiency a n d Electrolyte Effects of Inorganic Salts in Aqueous Gel C h r o m a t o g r a p h y An Error Analysis of Indicator M e a s u r e m e n t s

The analysis of errors in indicator plots shows that points in the vicinity of log / —· +0.7 are the most valuable in fixing the slope of a linear logarithmic plot. A. J. KRESGE and H. J. CHEN, Department Illinois Institute of Technology, Chicago, III.

of C h e m i s t r y , 60616

Anal. Chem. 41, 74

(1969)

In order to apply stcric exclusion for the characterization of inorganic polymers, the elution behaviors of simple salts and polymeric phosphate salts have been studied as functions of porosity and chemical nature of the gel. P. A. NEDDERMEYER and L. B. ROGERS, Department Chemistry, Purdue University, Lafayette, Ind. 47907 Anal. Chem. 41, 94 VOL. 4 1 , NO. 1, JANUARY 1969

·

of (1969) 13 A

AC Chemisorption of Carbon Monoxide on M e t a l Surfaces by Pulse C h r o m a t o g r a p h y

A pulse chromatographic procedure is used to measure the chemisorption of carbon monoxide on supported nickel and unsupported nickel and platinum catalysts. Results obtained on the supported nickel catalyst are compared with data from conventional volumetric procedures. C. S. BROOKS, United Aircraft Research Laboratories, East Hartford, Conn. 06108, and V. J. KEHRER, JR., Advanced Materials Research and Development Laboratory, Pratt and Whitney Division of United Aircraft Corporation, South Windsor, Conn. Anal. Chem. 41, 103 (1969)

BRIEFS

Resistance Compensation in N o n a q u e o u s Polarography. Evaluation of U n c o m p e n s a t e d Resistance a n d Effects of D a m p i n g in Two- a n d Three-Electrode Cells

Λ graphical method is presented for construction of an approximate residual current curve for a polarogram greatly distorted by uncompensated resistance. WILLIAM E. THOMAS, Jr., and WARD B. SCHAAP, ment of Chemistry, Indiana University, Bloomington,

Depart­ Ind.

Anal. Chem. 41, 136

(1969)

Nonunity Electrode Reaction Orders a n d Stationary Electrode Polarography M i c r o d e t e r m i n a t i o n of Fluorine in Organic C o m p o u n d s by Potentiometric Titration U s i n g a Fluoride Electrode

Determination results on typical microchemical fluorine standards in the range of 1 to 10 mg of sample are within the ± 0 . 3 % (absolute) values common for microelemental analysis. TRUMAN S. LIGHT and RICHARD F. MANNION, Center, The Foxboro Co., Foxboro, Mass. 02035

Research

Anal. Chem. 41, 107

A calcium-selective membrane electrode, which is not af­ fected potentiometrically by hydrogen ions and which lacks the complicated internal arrangement of inert sup­ port membrane and active ion exchanger and reference liquids, is evaluated. G. A. RECHNITZ and T. M. HSEU, Department of Chem­ istry, State University of New York, Buffalo, Ν. Υ. 14214

Anal. Chem. 41, 142

(1969)

Electrochemical Oxidation of Nitrite a n d Oxide on P l a t i n u m Surfaces in Fused Potassium Nitrate—Sodium N i t r a t e Eutectic M e l t s at 2 5 0 C

Data supporting the formation of a reversible couple be­ tween nitrite and N 0 2 gas in the melt is presented. I t is also suggested that oxidation of the oxide ion is a oneelectron process, and that the peroxide produced is de­ composed in a post chemical step. P. G. McCORMICK and H. S. SWOFFORD, Jr., Department of Chemistry, University of Minnesota, Minneapolis, Minn. Anal Chem. 41, 146

(1969)

(1969)

Determination of Trace Quantities of Thiourea a n d Cysteine by Hydrogen Overvoltage M e a s u r e m e n t on P l a t i n u m in Dilute Sulfuric Acid

A l t e r n a t i n g Current Polarography: Theoretical Predictions for Systems with First-Order C h e m i c a l Reactions Preceding t h e Charge T r a n s f e r Step

Calculations are presented that indicate a notable sensi­ tivity of ac polarographic observables to kinetic character­ istics of the reaction Υ ±=; Ο + ne R. Theoretical data provide insights into the expected response and appropri­ ate data analysis procedures. THOMAS G. McCORD a n d DONALD E. SMITH, D e p a r t m e n t of C h e m i s t r y , Northwestern University, Evanston, III. 60201 Anal. Chem. 41, 116

MARK S. SHUMAN, Department of C h e m i s t r y , Texas Chris­ tian University, Fort Worth, Texas 76129

(1969)

Analytical and Biochemical M e a s u r e m e n t s with a New, S o l i d - M e m b r a n e Calcium-Selective Electrode

Anal. Chem. 41,111

This study outlines the general method for obtaining theoretical current-potential curves when the electrode mechanism is mO -\- ne ^± qR and m and q have any in­ tegral values.

(1969)

Second H a r m o n i c Alternating Current Polarography: S o m e Experimental Observations with Quasi-Reversible Processes

Trace quantities of thiourea and e.ysteine can be detected at 10~*M and can be determined quantitatively between 10~7M and 5 X 10~'M. Detection of cysteine and methio­ nine is also possible with good precision for qualitative work. PAUL E. HOLLAND, J. T. PEELER, and A. J. WEHBY, Na­ tional Center for Urban and Industrial Health, U. S. De­ partment of Health, Education, and Welfare, Public Health Service, Cincinnati, Ohio Anal. Chem. 41, 153 (1969)

Potentiometric Determinations of C a l c i u m , M a g n e s i u m , and C o m p l e x i n g Agents in W a t e r a n d Biological Fluids

A detailed comparison of experimental results with theo­ retical predictions for the second harmonic wave shape and magnitude as a function of frequency is provided for the 2 systems, Cr(CN) 0 : , -/Cr(CN)o 4 - in \M K C N and C d 7 C d ( H g ) in \M Na,.SO t .

Calcium and magnesium are determined potentiometri­ cally by titration with tetrasodium salt solutions of ethyleneglycolbis-(betaaminoethylether)-iV,iV'-tetraacetic acid and ethylenediaminetetraacctic acid, respectively.

THOMAS G. McCORD and DONALD E. SMITH, Department of Chemistry, Northwestern University, Evanston, III. 60201

BART V A N T RIET and JAMES E. W Y N N , Department of Chemistry and Pharmaceutical Chemistry, Medical College of Virginia, Richmond, Va. 23219

Anal. Chem. 41, 131

(1969)

Anal. Chem. 41, 158 VOL. 4 1 , NO. 1, JANUARY 1969

·

(1969) 15 A

AC Notes

BRIEFS

Effect of t h e Gel C h r o m a t o g r a p h i c M e d i u m on Recoveries a n d Retention V o l u m e s

Gas C h r o m a t o g r a p h i c Analysis of Pyruvic a n d o-Ketoglutaric Acids

Based on the formation of quinoxalones, infrared and N M R spectral studies of these heterocyclics showed they existed entirely in the keto form and not in the hydroxyquinoxaline enol form.

Several commonly used gel media are compared for the separation of iron polymer on the basis of resolution and recovery. The behavior of stable inorganic and organic species on those media is also compared. C. H. LOCHMULLER and L. B. ROGERS, Department of Chemistry, Purdue University, Lafayette, Ind. 47907 Anal. Chem. 41, 173

N O R M A N E. HOFFMAN and THOMAS A. KILLINGER, Todd Wehr Chemistry Building, Marquette University, Milwau­ kee, Wis. 53233 Anal. Chem. 41, 162 (1969)

1 , 1 , 3 - T r i c y a n o - 2 - A m i n o - 1 - P r o p e n e — S p e c i f i c Reagent for Fluorometric D e t e r m i n a t i o n of Copper in M i c r o Amounts

The method is based upon the reaction that takes place in neutral to slightly alkaline media between 1,1,3tricyano-2-amino-l-propene and C u ( I I ) . A fluorescence is obtained upon the addition of excess acid at the end of the reaction. KIM RITCHIE and JOSEPH HARRIS, Barrow Neurological Institute of St. Joseph's Hospital, 350 W. Thomas Rd., Phoenix, Ariz. 80513 Anal. Chem. 41, 163 (1969)

Gas C h r o m a t o g r a p h i c D e t e r m i n a t i o n of Plasticizers a n d Stabilizers in C o m p o s i t e Modified Double-Base Propellants

A column packed with OV-17 on Gas Chrom Q combined with the technique of programmed temperature on-column injection of the sample permits the analysis of stabilizers and plasticizers in C M D B propellants without interfer­ ences caused by N G breakdown. J. M. TROWELL and M. C. PHILPOT, Bacchus Works, Magna, Utah

Hercules

Direct R e a d i n g Emission S p e c t r o m e t r i c D e t e r m i n a t i o n of Trace M e t a l s in C a l c i u m Sulfate M i n e r a l s by Organic E n r i c h m e n t

C d and Lu, fused in mixed with the solid were used as internal out at a p H of 5.9 and

a sodium m-phosphate buffer and enriched sample prior to analysis, standards. Precipitation is carried Al is used as the collector.

EDGAR F. CRUFT and JOHN HUSLER, Department of Geology, University of New Mexico, Albuquerque, Ν. Μ. 87106 Anal. Chem. 41, 175 (1969)

D e t e r m i n a t i o n of I m p u r i t i e s in S o d i u m by L a n t h a n u m Hydroxide C a r r i e r Precipitation a n d Spectrographic Analysis

Fe, Ni, Cr, Mn, and Co are determined quantitatively with a precision of ± 1 3 % and some other 31 elements are estimated semiquantitatively within a factor of two. ROY KO and PAMELA ANDERSON, oratory, Battelle Memorial Institute,

Pacific Northwest Richland, Wash.

Anal. Chem. 41, 177

Lab­ (1969)

Incorporated,

Anal. Chem. 42, 166

(1969) Solvent Composition Effects in Thin-Layer C h r o m a t o g r a p h y Systems of t h e T y p e Silica Gel—Electron Donor Solvent

Solution of Blank P r o b l e m s in 1 4 - M e V N e u t r o n Activation Analysis for T r a c e Oxygen

Two problems discussed are determination of the attenu­ ation of the activity from the container by samples of different diameters, and definition of a geometric model which quantitatively expresses the observed attenuation by the samples. S. S. NAGOLWALLA, E. P. PRZYBYLOWICZ, J. DUETH, and S. L. BIRKHEAD, National Bureau dards, Washington, D. C. 20234 Anal.

(1969)

E. of

Chem. 41, 168

SUDStan­

EDWARD SOCZEWINSKI, D e p a r t m e n t of Inorganic and Analytical Chemistry, Medical Academy, Lublin, Poland Anal. Chem. 41, 179

(1969)

(1969)

A Gas C h r o m a t o g r a p h i c P r o c e d u r e for t h e S i m u l t a n e o u s D e t e r m i n a t i o n of Pyridoxine, Ascorbic A c i d , a n d N i c o t i n a m i d e in V i t a m i n Capsules a n d Tablets

jV,0-Bis(trimethylsilyl)aeetamide is reacted with the con­ tents of a multivitamin capsule or tablet and the resulting solution chromatographed with phenanthrene as internal standard. LAWRENCE T. SENNELLO and C. J. ARGOUDELIS, Depart­ ment of Food Science, The Burnsides Research Laboratory, University of Illinois, Urbana, III. 61801 Anal. Chem. 41, 171

A simple approach to characterize solvent composition effects in certain types of adsorption systems is reported which is analogous in theory to that used in the treat­ ment of partition systems involving the formation of solvation complexes.

(1969)

Differential S p e c t r o p h o t o m e t r i c D e t e r m i n a t i o n of E u r o p i u m in Y t t r i u m E u r o p i u m V a n a d a t e U s i n g a n Expanded-Scale Absorption Slidewire

The technique described uses an expanded-scale slidewire and appropriate reference solutions to extend the range of precise spectrophotometric analysis to small amounts of europium, permitting absorbances of from 0.0 to 0.2 to be read at ±0.0001. EDWARD W. LANNING, The Bayside Laboratory, Research Center of Genera/ Telephone & Electronics Laboratories, Inc., Bayside, Ν. Y. Anal. Chem. 41, 182 (1969) VOL. 4 1 , NO. 1, JANUARY 1969

·

17 A

AC Near-Infrared Spectrophotometric Analysis of Ethylene-Propylene Copolymers The combination, tone region is studied with Ε—Ρ copoly­ mers and physical blends of homopolymers with absorbances at 2.466 μ as well as at 2.275, 2.31, and 2.35 μ. Absorbances ratios associated with the 2.466-μ band intro­ duce less fluctuations than the other ones.

BRIEFS

Amperometric Titration of Corypalline with Sodium Tetraphenylborate at the Intermittently-Polarized Rotating Pyrolytic Graphite Electrode The standard deviation in the titration of 5.060 vo.M KC1 •at -f-0.55 V was ±0.4%. Corypalline was titrated directly at +0.55 V and +0.70 V, respectively, and indirectly by addition of T P B and back-titration with KC1.

TSUGIO TAKEUCHI, SHIN TSUGE, and YOSHIHIRO SUGIMURA, Institute of Analysis, Faculty of Engineering, Nagoya University, Japan Anal. Chem. 41, 184 (1969)

JOHN T. STOCK and R. D. PUGLIESE, University Connecticut, Storrs, Conn. 06268

Oxidation of Coordinated Thiourea in Copper(l)— Thiourea Complexes by Copper(ll)—Perchlorate in Acetonitrile

Calcium Activity Measurements Using a Liquid Ion Exchange Electrode in Concentrated Aqueous Solutions

A gradual increase in potential is observed with the progressive addition of oxidant. A sharp jump in potential (200 to 250 mV) is registered at the end point of the titration. H. C. MRUTHYUNJAYA and A. R. VASUDEVA MURTHY, Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 12 Anal. Chem. 41, 186 (1969) Molecular Flame Absorption Spectrometry for Sulfur

of

Anal. Chem. 41, 198 (1969)

The systems described shows Nernstian behavior in solu­ tions of high concentration (up to 5.5ΛΟ if the internal reference solution is matched in concentration with the test solution. RIMA HUSTON and JAMES N. BUTLER, Tyco Laboratories, Inc., Waltham, Mass. 02154 Anal. Chem. 41, 200 (1969) Sodium Ion-Selective Electrode Studies of Ion Association in Solutions of Sodium Tetrametaphosphate and Trimetaphosphate

The 3200-2609 A, 2300-1800 A , a n d 1580-^1520 Â absorption bands and those below 1350 Â are utilized in the determination of sulfur. The analytical detection limit is 10 ,ug with the present apparatus.

This work supports the conclusions of Bates—i.e., within experimental error, no difference could be detected be­ tween total and free sodium concentrations within the range [Na + ] = 5 X 10"4 to 5 X 10"3 and [HPO, 2 "] = 10"1 to 10Λ

KEIICHIRO FUWA and BERT L. VALLEE, Biophysics Research Laboratory, Department of Biological Chemistry, Harvard Medical School, and Division of Medical Biology, Department of Medicine, Peter Bent Brigham Hospital, Boston, Mass. Anal. Chem. 41, 188 (1969)

GARY L. GARDNER and GEORGE H. NANCOLLAS, Depart­ ment of Chemistry, State University of New York at Buffalo, Buffalo, Ν. Υ. Anal. Chem. 41, 202 (1969)

Determination of Degree of Cure of Polymeric Materials through Evaporative Rate Analysis An economical, simple method by which the rate of cure of polymeric materials may be followed as a function of pressure, temperature, and time is described. Approximately 2 minutes per analysis are required. EUGENE CERCEO, Vertol Division, The Boeing Co., Philadelphia, Pa. 19142 Anal. Chem. 41, 191 (1969) Determination of Tantalum and Its Separation from Niobium and Other Closely Associated Elements Using Tetra-N-Pentylammonium Bromide Tantalum is quantitatively precipitated as tetra-n-pentylammonium tantalum hexafluoride which is subsequently fired and the tantalum weighed as TaaOs. R. G. DOSCH, Sandia Laboratory, Albuquerque, Ν. M. Anal. Chem. 41, 193 (1969) Direct Ultraviolet Spectrophotometric Determination of Benzene in Aqueous Solutions The technique reported which excludes all possible losses of benzene gave experimentally determined values of A that are higher than those previously reported by approxi­ mately 14%. DENNIS G. MARKETOS, Nuclear Research Center "Democritos," Radiation Chemistry Laboratory, Aghia ParaskeviAttikis, Athens, Greece Anal. Chem. 41, 195 (1969)

Errors in Coulometric Chloride Titrations Due to Photodecomposition of Silver Chloride For titrations where precision and accuracy of the order of 0.005%· is satisfactory, a correction based on the fitted equation, R = at + bt2 + ci3, is applied to titrations not protected from the light. CHARLES E. CHAMPION and GEORGE MARINENKO, Insti­ tute for Materials Research, National Bureau of Standards, Washington, D. C. 20234 Anal. Chem. 41, 205 (1969) Coulometric Titration of Mercury Fulminate with Electrogenerated Iodine The content of 200-mg samples of standard grade mercury fulminate was determined coulometrically as well as titrated in accordance with the Bofors' method, both aeidimetrically and iodometrically. A. J. VAN DER HULST, Technological Laboratory, National Defence Research Organisation TNO, Rijswijk (Z.H.), The Netherlands Anal. Chem. 41, 207 (1969) Brunauer-Emmett-Teller Specific Measurement of Solids Using Krypton No fundamental differences were found to exist between the use of s "Kr or Ν as the measuring gas in the B.E.T. method. Samples of Al 2 03-Si0 2 , A1203) aFe2Os, Ti0 2 , aFeOOH, Fe, and human hair were examined. JAN MEDEMA and J. P. W. HOUTMAN, Reator Instituât, Delft, Netherlands Anal. Chem. 41, 209 (1969) VOL. 4 1 , NO. 1, JANUARY 1969

·

19 A

A C BRIEFS

INDICATING DESICCANT

Polarographic Behavior of l-Hydroxypyridine-2-Thione

The effect of pH on the polarographic behavior of 1-hydroxypyridine-2-thionc is studied in aqueous and ethanolic media. ALAN F. KR/VIS, Department of Chemistry, The University of Akron, Akron, Ohio 44304, and EUGENE S. GAZDA, Oiin Mathieson Chemical Corp., New Haven, Conn. Anal. C h e m . 41, 212

(1969)

Determination of Hydrogen in Partially Deuterated Water

The method offers an accuracy of approximately 0.002 in χα, the atom fraction of ordinary hydrogen and is par­ ticularly convenient for applications where other spectrophotometric measurements have been made on the same samples. MAURICE M. KREEVOY a n d THOMAS S. STRAUB, Schoo/ of Chemistry, University of Minnesota, Minneapolis, Minn. Anal. Chem. 41, 214 (1969)

Conversion of Polarographic and Other Potentials f r o m One Reference Electrode to Another

The emf of a galvanic cell consisting of two reference electrodes, which are connected to each other through the sample solution, are used to convert polarographic and other potentials measured against one reference electrode to values vs. the other reference electrode. ΚΕΙ/CHI TSUJI and PHILIP Michigan, A n n Arbor, Mich.

J. ELV/NG, The University of Anal. C h e m . 41, 216

(1969)

Correspondence Controlled Surface Porosity Supports for High Speed Gas and Liquid Chromatography J . J. K/RKLAND, E. I. du Pont de Nemours & Co., Inc., Industrial and Biochemicals Dept., Experimental S t a t i o n , W i l m i n g t o n , Del. Anal. Chem. 41, 218 (1969)

Aids for Analytical Chemists Electronic M e a s u r e m e n t of t h e T i m e Constant of Exponential Recovery in Nuclear Magnetic Resonance ANTHONY L. VAN GEET and LAZAR D. WECHSLER, De­ p a r t m e n t of Chemistry, State University of New York, Buffalo, Ν. Υ. 14214 Anal. Chem. 4 1 , 220 (1969)

Anal. Chem. 41, 223

Indicating DRIERITE is a chemical drying agent for the efficient and rapid drying of air and gases in systems where visual indication of active desiccant is desired. In use, the color changes sharply to a rose-red as the margin between the exhausted and active desiccant progresses through the tube or column. It is available in 8 Mesh, the standard granule size, and in 20-40, 10-20, 6 and 4 Mesh. Impregnated with cobalt chloride, Indicating DRIERITE retains the high efficiency of Regular DRIERITE, anhydrous calcium sulfate, plus the added advantage of the color change for indication. It dries air and gases to a terminal dryness of 0.005 milligram per liter of gas. Regeneration reverses the color change and makes possible repeated use after heating at 375-450°F while spread one granule deep for one hour. Regular white DRIERITE (non-indicating) is available in the above mentioned sizes and also in 200 Mesh and 325 Mesh. DRIERITE is a product of the W. A. Hammond Drierite Co., Xenia, Ohio. Available from your nearest LABORATORY SUPPLY HOUSE.

DRIERITE

Spinning Band Distillation C o l u m n Still Heads R. E. JENTOFT, W. R. DOTY, a n d T. H. GOUW, Research Co., R i c h m o n d , Calif. 9 4 8 0 2

INDICATING DRIERITE changes from blue when dry to rose-red when exhausted

Chevron (1969) Circle Να. 25 on Readers' Service Card

VOL 4 1 , NO. 1, JANUARY 1969

·

21 A