Application of phase equilibria to gas chromatographic trace analysis

Vitenberg, A. G.; Ioffe, B. V.; Борисов, В. Н.

doi:10.1007/bf02269053

Cited by 31 publications

(8 citation statements)

References 43 publications

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“…To increase the sensitivity of microimpurity determination in solutions, we used head-space analysis. This technique finds increasingly extensive use in the trace determinations (3) of sulfur compounds (7)(8)(9)(10).…”

Section: Resultsmentioning

confidence: 99%

“…The key condition for a successful use of the head space analysis of the sulfur impurities in solutions is the exclusion of adsorption losses of the compounds of interest, as well as of losses involved in sampling, injection in the chromatograph, and in the chromatographic process itself. The existing devices for establishing equilibrium distribution of a compound between a liquid and gas and the techniques of injecting the equilibrium gas in the chromatograph do not preclude such losses since they have rubber membranes and the injection is accompanied by a change in the analyte concentration in the gas phase (3).…”

Section: K=c~g (1>mentioning

confidence: 99%

“…Because of the high toxicity of these pollutants, the corresponding tolerance limits for their content are very low, their analysis thus requiring extremely sensitive methods which should permit selective determination of impurities at the 10~5% level or 0.1 ppm. These requirements are best met by gas chromatography (1) which is widely used in the analysis of sulfur compounds (2), in particular in trace amounts (3).…”

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Gas chromatographic determination of trace amounts of sulfur compounds in industrial effluents

Vitenberg¹,

Кузнецова²,

Butaeva³

et al. 1977

Anal. Chem.

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speed of analysis, and adequate sensitivity were attained. And the results obtained were comparable to the results of an established ASTM method.Concerning cost of equipment, a GC already owned by a laboratory can be used if it is equipped with an FPD and a gas mixing device, or a very inexpensive GC may be purchased. Even if all the necessary equipment has to be purchased, costs are only a little more than those required for the Lamp Method. Amortization of the equipment can readily be seen in the following rationale: The Lamp Method can analyze 12 samples per man day and a lead correction is necessary. The FPD method can analyze 60 samples per man day and no lead content correction is necessary. A fivefold increase in throughput is anticipated using the same staffing level. At an assumed figure of $80/man day the costs for replacing the Lamp Method by the GC/FPD are amortizable in less than three weeks.

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Section: Resultsmentioning

confidence: 99%

Section: K=c~g (1>mentioning

confidence: 99%

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Gas chromatographic determination of trace amounts of sulfur compounds in industrial effluents

Vitenberg¹,

Кузнецова²,

Butaeva³

et al. 1977

Anal. Chem.

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“…This method, the so-called headspace analysis, has been thoroughly tested in trace impurity analysis (Vitenberg et al, 1974), collection of thermodynamically relevant data for the characterization of non-ideal solutions (Kolb, 1975) and determination of the constant of chemical equilibria in solution (Vitenberg et al, 1976). It has been experimentally studied by chromatographic analysis of the vapor phase using an apparatus designed by ourselves.…”

mentioning

confidence: 99%

“…It has been experimentally studied by chromatographic analysis of the vapor phase using an apparatus designed by ourselves. This method, the so-called headspace analysis, has been thoroughly tested in trace impurity analysis (Vitenberg et al, 1974), collection of thermodynamically relevant data for the characterization of non-ideal solutions (Kolb, 1975) and determination of the constant of chemical equilibria in solution (Vitenberg et al, 1976). The last application is very close to the characterization of reactive distillation equilibrium, so the reliability of our apparatus has been evaluated by measuring the ionization constant of some volatile amines.…”

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Reactive distillation of pyridine mixtures with an organic acid. I. Determination of the reactive distillation equilibrium

Duprat¹,

Gau²

1991

Can J Chem Eng

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The reactive distillation equilibrium has been experimentally determined by chromatographic analysis of the vapor phase for various mixtures of two pyridines plus an organic acid in stoichiometric deficiency in an organic solvent. Protonation of pyridines by a weak acid seems to involve ion pair formation, while protonation by a strong acid seems to result in free ion formation, and may involve a small quantity of triple molecule ions (two pyridine molecules for one acid molecule). Steric effects are not significant in such ion formation and the chemical equilibrium constant can be predicted from the pyridine pK, difference using a linear relationship. Despite the possible formation of triple molecule ions, the reactive distillation equilibrium at constant acid quantity can be reasonably well described as an ideal liquid-vapor equilibrium combined with an ideal chemical equilibrium. However, the increase of the chemical equilibrium constant with the acid quantity should be taken into account in a more refined model. On a dttermint de facon exptrimentale l'tquilibre de la distillation reactive par I'analyse chromatographique de la phase vapeur pour des mtlanges divers de deux pyridines plus un acide organique dans des conditions de dtficience stoechiomttrique dans un solvant organique. La protonation de pyridines par un acide faible semble entrafner la formation de paires d'ions, tandis que la protonation par un acide fort semble conduite h une formation d'ions libres et donner une petite quantite d'ions triples (deux moltcules de pyridine pour une moltcule d'acide). Les effets sttriques ne sont pas importants dans une formation d'ions de ce type et la constante d'tquilibre chimique peut Ctre prMite ii partir de la difftrence pK, de la pyridine par une relation lintaire. Malgrt la formation possible d'ions triples, I'tquilibre de la distillation rtactive avec des quantitts d'acide constantes peut Ctre raisonnablement dtcrit c o m e un tquilibre liquidevapeur idtal combint ? I un tquilibre chimique idtal. Cependant, I'augmentation de la constante d'tquilibre chimique avec la quantitt acide devrait stre prise en compte dans un modkle plus precis.

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