Colorimetric determination of free fatty acids in biological fluids

Following the introduction by Duncombe of a colorimetric micromethod for the determination of free fatty acids (FFA) dissolved in chloroform, we studied the optimum conditions for chloroform extraction of FFA from blood or other biological fluids. A degree and rate of extraction similar to those with Dole's extraction mixture were obtained.Phospholipids are not extracted by the procedure described. As little as 0.2 ml of whole blood, instead of serum or plasma, can serve as a FFA sample in the subsequent colorimetric determination, which has been modified to render it simpler and more sensitive.