Improvements in or relating to the separation of organic compounds by gas chromatography

摘要

An active constituent for use in the resolution of a mixture of organic compounds by gas chromatography comprises a mixture of a particulate organo-clay wherein some or all of the replaceable inorganic cations are replaced by organic cations, and a modifying agent which is a liquid of low volatility at the temperature of operation, is a solvent for at least one component of the organic mixture and reacts chemically with neither the organo-clay nor the components of the organic mixture. The organoclay may be a montmorillonoid, a nontronite or a montmorillonite, e.g. bentonite. The organic cation may be a quaternary ammonium ion containing long chain alkyl groups or both alkyl and aryl groups, a preferred compound being dimethyl dioctadecyl ammonium bentonite. A wide range of classes of organic compounds including petroleum fractions and organopolysiloxanes are specified as suitable modifying agents whilst the use of phenyl methyl and dimethyl silicones, aqualene, polyethylene glycol and tolyl phosphate are specifically exemplified. The modifying agent may be used 0,2-3,0 parts, but preferably 0,3-2,0 parts by weight per part of organo-clay and the mixture thereof may be used on an inert support, e.g. Kieselghur. Ranges of size and ratios of active constituent to support are specified. The separation of mixtures of up to 23 hydrocarbons is described.