Selection of internal standards for determining quantitative recovery of isoprenoid [fatty] acids after urea complexing [Animal fats]

Various types of esters are considered as internal standards for the quantitative gas liquid Chro‐matographic determination of isoprenoid fatty acids after urea complex treatment of esters of total or saturated fatty acids. It is shown that aromatic esters are potentially unsuitable because of on‐column losses with polyester columns. Two classes of ali‐phatic esters, either of 2‐ethyl‐l‐hexanol, or of 3‐cyclohexylpropionic acid, have been evaluated as satisfactory and certain gas liquid Chromatographic retention data is given to show which ester might be selected for a particular application.