A Rapid and Simple Method for the Determination of Esterified Fatty Acids and for Total Fatty Acids in Blood

Abstract

Carboxylic acid esters react with hydroxylamine in alkaline solution to form hydroxamic acids.These acids produce a red to violet reaction with ferric chloride which has been utilized by Feigl (1949) for the microchemical detection of carboxylic acid derivatives.Lipmann and Tuttle (1945) developed a method for the quantitative assay of acylphosphates by allowing hydroxyl- amine to react with these substances in aqueous solutions at pH 6.0.Hestrin (1949) adapted the reaction for the estimation of short-chain esters by employing alkaline aqueous reagents.Under these conditions esters of higher fatty acids did not react.In order to achieve a reaction of neutral fats and other natural lipids with these reagents, Bauer and Hirsch (1949) employed strictly an- hydrous conditions and developed a method for the determination of the total esterified fatty acids in blood serum.Since almost all the fatty acids in blood serum are in esterified form, this method gives results identical with those testing total fatty