GAS FACTS published periodically for analytical chemists
To remedy this situation, Scott has begun an experimental program to evaluate several systems of interest to chromatographers. First to be Miscibilities in examined was methanol/ supercritical carbon dioxide. A few of the experimental curves are fluids shown. It can be seen that In supercritical fluid chromasolubility of methanol in C02 tography, the use of a mobile is not significantly influenced phase containing a polar by either temperature or compound, ie, CH3OH in C02, pressure changes in the region can change separation propbelow 100 atmospheres—and erties without altering that in this pressure range, critical temperature, viscosity mole fraction of the alcohol or density of the fluid. Such must be kept below 0.15 to additions can greatly extend maintain a homogeneous the applications of this system. Above about 120 analytical method. However, atmospheres, pressure and it is necessary to know the temperature both exert miscibility of the two comsignificant effects. During ponents under operating conthe experiments, it was also ditions. Unfortunately, observed that after temperaexperimental data do not ture changes, several hours exist and sufficient data are were required before the not available for use in system reached a new 1 Peng-Robinson or other equilibrium. theoretical models. If you are interested in learning more of this pioneering work, get in touch with Scott. We'll be happy to discuss with you our efforts to generate solubility information so essential for chemists involved in supercritical fluid chromatography and extraction. You can also learn about mixtures at conditions near and below the critical point.
BRIEFS Control of Dispersion and Variation of Reaction Coil Length in Flow Injection Analyzers by Flow Reversals 1236 D. Betteridge, P. B. Oates, and Adrian P. Wade*, British Petroleum Research Centre, Chertsey Road, Sunbury-on-Thames, Middlesex, TW16 7LN, U.K. Anal. Chem., 59 (1987)
'Peng. DY and Robinson. DB. IndEna ChemFundam. 1976. I. 59-64.
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CIRCLE 150 ON READER SERVICE CARD 562 A · ANALYTICAL CHEMISTRY, VOL. 59, NO. 8, APRIL 15, 1987
Aids for Analytical Chemists Derivatization Procedure for Gas Chromatographic Determination of Hydroxylamine
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Robert L. Pesselman, Michael J. Foral, and Stanley H. Langer*, Department of Chemical Engineering, University of Wisconsin, Madison, Wis. 53706 Anal. Chem., 59 (1987)
Inductively Coupled Helium Plasma as an Ion Source for Mass Spectrometry 1240 Akbar Montaser* and Shi-Kit Chan, Department of Chemistry, The George Washington University, Washington, D.C. 20052, and David W. Koppenaal, Mineral Studies Laboratory, Bureau of Economic Geology, The University of Texas at Austin, Austin, Tex. 78712 Anal. Chem., 59 (1987)
Interchangeable Insert Thermospray Probe
1242
Steve E. Unger*, Terry J. McCormick, Mark S. Bolgar, and John B. Hunt, The Squibb Institute for Medical Research, P.O. Box 4000, Princeton, N.J. 08540 Anal. Chem., 59 (1987)
Improved Method for Determination of Stern-Volmer Quenching Constants 1244 David J. Desilets, Peter T. Kissinger, and Fred E. Lytle*, Department of Chemistry, Purdue University, West Lafayette, Ind. 47907 Anal. Chem., 59 (1987)
Applications of a Versatile Injection Valve for Flow Injection Analysis 1246 Brice C. Erickson and Bruce R. Kowalski*, Department of Chemistry, University of Washington, Seattle, Wash. 98195, and Jaromir Ruzicka, Chemistry Department A, The Technical University of Denmark, 2800 Lyngby, Denmark Anal. Chem., 59(1987)
Correction. Sampling and Excitation of Refractory Solids with a Theta Pinch Discharge Designed as an Atomic Emission Source 1248 Jeffrey S. White and Alexander Scheeline*, School of Chemical Sciences, University of Illinois, 1209 West California St., 79 RAL, Box 48, Urbana, 111. 61801 Anal. Chem., 59 (1987)
