Preparation of standard vapor-gas mixtures for gas chromatography: continuous gas extraction

Abstract

Science Program at USC, and tothe Swedish Environmental Protection Board for their encouragement and financial (30) Yalkowski, S. H.; Valvanl, S. C.; Mackay, D. Residue Rev. 1083, 85, 43-55. (31) Aibro, P. W.; Corbett, J. T.; Schroeder, J. L. J . Chromatogr. The possibilities of using gas extractlon under dynamic conditlons in preparing gas mlxtures of known concentratlons for equipment testing and the development of analytical technlques are discussed. Conditions are specified for the preparation of mixtures in whlch the concentration of volatile components decreases regularly by contlnuous gas extraction from solutions. These methods widen the possibilities of using the exlstlng dynamic variatlons of Preparation vapor-gas mixtures and make it possible to operate with hlgh boiling, high polar, and unstable substances. Proposed methods were tested for hydrocarbon solutions in squalane or poly( ethylene glycol) from whlch vapor-gas mixtures at concentratlons ranging from 1 mg/ma to 50 mg/L were prepared.

Activity Coefficients at Infinite Dilution of Alkanols in the Ionic Liquids 1-Butyl-3-methylimidazolium Hexafluorophosphate, 1-Butyl-3-methylimidazolium Methyl Sulfate, and 1-Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl) Amide Using the Dilutor Technique

“…Hence, several authors, particularly from Russia, prefer to use the term "continuous gas extraction". 21,22 A scheme of the dilutor technique used in the present work is shown in Figure 1. This kind of equipment was already described previously.…”

The possibilities of a mass spectrometer equipped with a Llewellyn inlet system in the analysis of air and water samples

“…Standard gases with concentrations in air of styrene and p-xylene beginning at 1.18 ppm (5.6 mg/m 3 ), and of toluene and benzene of 2.18 ppm (7.8 mg/m 3 ), were prepared using a head space vapor-gas source (HSVS) [5]. Polydimethylsiloxane in the shape of a tube 30 mm long and with inner and outer diameters of 0.63 mm and 1.18 mm, respectively, was used as the first membrane of the inlet system.…”

“…When analyzing air mixtures during our experimental check of the inlet system, a (HSVS) [5] was used that ensured constant concentrations (the error was no greater than 7%) of the target components: 2.2 ppm for toluene, 1.8 ppm for benzene, and 1.2 ppm for styrene and p-xylene at an ambient temperature of 20°ë in a sample flow of up to 300 mL/min.…”

Utilization of a multimembrane inlet and a cyclic sudden sampling introduction mode in membrane inlet mass spectrometry

“…Gas standards of toluene, benzene, styrene, and p-xylene of 1.18 ppm-2.18 ppm (or 5.6 mg/m 3 -7.8 mg/m 3 ) concentrations in 95% nitrogen and 5% oxygen mixture were prepared using a head 1,2,3) through the multimembrane inlet system into a mass spectrometer and relative enrichment of the sample with compounds with the different permeabilities ( c ) in non-steady-state sudden sampling introduction mode depend on the extension of the time interval between the moment of sample supply to the inlet system and the time of measurement t I , t II , or t III , where t c ss is the time required to achieve steady state flow of Compound c through the entire membrane inlet, c is the response time of Compound c for a one membrane interface. space vapor-gas source (HSVS) [10], allowing the preparation of gas mixtures with vapor concentrations from 0.01 to 1000 mg/m 3 for volatile organic compounds. The uncertainty in the preparation of the gas mixtures with the HSVS is 2-7% at constant temperature.…”