Reliable measurement of non-esterified long-chain fatty acid pattern in blood plasma.

In this reliable assay for determining the non-esterified long-chain fatty acid pattern in plasma, only 100 microliters of sample are needed and a single assay can be done within 40 min. The isolation procedure was performed by adsorption of fatty acids from plasma onto graphitized carbon black (Carbopack B) using a column method. After desorption and removal of the eluting phase, fatty acids are methylated by diazomethane and quantified by packed column gas chromatography. Analytical recoveries ranged between 91% and 103%. Within-run precision gave coefficients of variation of 2.3% and 11% for fatty acid concentrations of 58.2 and 0.6 mumol/l, respectively. Studies of plasma samples under various storage conditions indicated that reliable measurement of the non-esterified fatty acid fraction can be obtained even after 60 days if specimens are conserved at -18 degrees C in the presence of a suitable phospholipase inhibitor.