Volatile Fatty Acid Analyses of Blood and Rumen Fluid by Gas Chromatography

Abstract

A quantitative method by gas chromatography for the determination of free fatty acids in rumen fluid and blood was developed. Five ml. of strained rumen fluid and 1 ml. metaphosphoric acid are centrifuged 3000 rpm for 10 min. Without further preparation the supernatant is chromatographed. A protein-free filtrate (folin-wu) of 20 ml. whole blood is made basic with KOH and lyophylized. The salts are taken up with 3 ml. acid and chromatographed without further preparation. A 1 meter 1/4 in. stainless steel column was packed with a mixture of 20% Twenn 80 and 2% phosphoric acid on Chromosorb W (60-80). A column temperature of 120[degree] C was used with nitrogen carrier gas flow of 120 ml./min. The hydrogen and air flow to the flame lonization detector was 35 and 250 ml./min. with a direct current of 300 volts across the flame. Under these conditions free fatty acids from acetate to valerate and their isomers can be separated in symmetrical peaks in 18 min.