Assay of serum free fatty acids by extraction-photometric procedure

Reaction conditions for extraction-photometric determination of free fatty acids in serum were studied. The results were found to be influenced by (a) sodium chloride concentration in the copper reagent, (b) the kind of standard solution used, (c) centrifugation of the reaction mixture and (d) serum phospholipids. A micromethod based on the formation of free fatty acids-copper soaps with a stable copper reagent and sensitive indicator for copper, 2-(2-thiazolylazo)-4-methoxyphenol, is described.