Direct determination of low molecule fatty acids by gas-liquid chromatography.

Abstract

In order to determine fatty acids directly by gas-liquid chromatography, stearic acid and sebacic acid have been used conventionally as the column material.
In the authors studies however, an innegligible evaporating loss of these acids from column was observed. This caused the gradual changes in retention time and separation effect and made these acids unsuitable for the purpose.
The authors tried to use the high-boiling and low-melting behenic acid as a column material. G. Raupp's column packing with 85 parts dioctyl sebacate and 15 parts sebacic acid on 3 times quantity of celite 545, was modified, and the column packed with 1 part dioctyl sebacate and 1 part behenic acid on 3 times quantity of celite 545 was recommended. The column temperature was maintained at 150°C, and the flow rate of carrier gas (He) was adjusted to 40 ml/min.
The mixture of water, formic acid, acetic acid, n-propionic acid, iso-butyric acid, n-butyric acid, iso-valeric acid, crotonic acid, n-valeric acid and n-capronic acid was separated into each component completely, and no evaporating loss of behenic acid from column was observed after 70 hours.