Serum PhospholipidsDetermined without Acid Digestion

A method for determination of phospholipids in serum is described that involves complexing intact phospholipids with chromogenic reagent, thus eliminating the need for acid digestion, which is a mandatory step in all the current procedures for phospholipid analysis. Inorganic phos-phorus and other serum components do not interfere in the determination. Excellent agreement between results of this new procedure and the conventional acid digestion method (r = 0.986, y intercept = 3.053, and slope = 0.986) makes it an attractive alternative clinical method for determination of phospholipids in serum. AddItIonal Keyphrase: normal values In clinical laboratories, total serum phospholipids are measured by procedures that are based on obligatory conversion of phospholipid phosphorus to inorganic phosphorus by acid digestion, usually with H2S04 and H2O2 or HC1O4 (1). Recently a colorimetric procedure described by Raheja et al. (2) obviates the need for acid digestion. In their procedure a modified spray reagent (chromogenic solution) formulated by Vaskovsky and Kostetsky (3) is used for color development with intact phospholipids. They reported assays for only purified phospholipids, and did not apply the technique to serum phospholipid determination. Here, I describe a new approach to the routine anal-ysis of serum phospholipids that eliminates the need for acid digestion. Materials and Methods All chemicals were of analytical grades and were used without further purification