Determination of free fatty acids: a comparative study of the enzymatic versus the gas chromatographic and the colorimetric method.

We determined the concentration of free fatty acids in 51 plasma samples by three different methods: a gas-liquid chromatographic, a colorimetric and an enzymatic method. Values obtained by the three methods show a good correlation. The gas-liquid chromatographic method was used as the reference method. The results of the enzymatic method are about 5% too high and the colorimetric results have a bias of +27%. The coefficients of variation of the three assays are 4, 7 and 5% respectively. Storage of the samples at -18 degrees C gives no change in the total amount of free fatty acids, enzymatically determined. Because of low costs (time, reagents and apparatus), combined with a sufficient accuracy and precision, the enzymatic method for the determination of total free fatty acids is the method of choice.