Oleate replacement ultrafiltration: A new method for quantitative recovery of organic acids from human plasma

Abstract

A method was developed for the isolation of organic acids in high yields from body fluids containing a high protein content. The method, which includes ultrafiltration followed by anion-exchange chromatography, was used to recover organic acids from human plasma. It is based on the addition of oleic acid to the plasma sample before the ultrafiltration step. The oleic acid, which effectively competes for binding sites on the protein, results in the release of other organic acids, which are then recovered in the ultrafiltrate. Comparison of the recovery of various acids (with and without added oleic acid) shows that the yield of certain acids (like citric acid) can be increased by more than an order of magnitude when oleic acid is added to the plasma sample. The satisfactory reproducibility of this method, even for small amounts of plasma (less than 1 ml), makes it suitable for quantitative metabolic profiling analysis.