Gas-chromatographic method for determining the solubility of gases in liquids

Abstract

DETERMINING the solubility constant of oxygen in organic compounds is an important technical problem. To solve this problem gas-chromatographic methods, as well as conventional statistical methods, have been used in recent years. Well known gas-chromatographic methods of determining distribution constants may be conventionally separated into two groups. In one group the gas chromatography is used as an analytical method to determine dissolved gases liberated from high boiling solvents. In the second group the distribution constant is determined directly from chromatographic retention values. The latter well developed group of methods is based on a conventional relationship between retention volume and distribution coefficient [2, 3]. I t was found experimentally, that in the range of low concentrations, the distribution coefficient is constant and for polar compounds is independent of the amount of stationary liquid phase, the type and flow rate of carrier gas, the type of solid carrier and column length [4]. Porter [5] determined the solubility of paraffin, cyclic hydrocarbons and alcohols in di-isodecylphthalate for the first time by gas-liquid chromatography. The methods involved the use of a solvent as stationary liquid phase in the chromatographic column and the dissolved material was added by a pulse method in the carrier gas flow. Subsequently [6] the same authors determined the solubility of chlorine and nitrosyl chloride in Cle-C20 paraffinic hydrocarbons at a temperature somewhat higher than the melting point of solvents. The method assumes the use of a pure solvent, the dissolved material may be purified in a preliminary column. The accuracy of solubility measurement by this method is considerably affected by solvent volatility. The authors of another study [4] proposed to use for volatile solvents hermetically closed columns joined to the system by injection needles to enable them to be disconnected easily from the device and less of solvent determined by weighing. The distribution constants of acetylene hydrocarbons in N,Ndimethylformamide obtained by this method agree with data obtained by the statistical method.