Determination of lipid-bound sulfate by ion chromatography and its application to quantification of sulfolipids from kidneys of various mammalian species

A variety of procedures have been developed for determining the sulfate est er content of various biomolecules. Ion chromatography (IC), that is, quant itation of ionic substances by ion conductimetry after separation by anion- exchange chromatography, has been increasingly utilized for the determinati on of inorganic sulfate in clinical and environmental samples. We adopted s uppressed-mode IC to the determination of lipid- or glycolipid-bound sulfat e released by acid hydrolysis and found that it has the advantage of increa sed precision for wide concentration ranges (30 pmol to similar to mu mol) and lack of interference from other lipids. To minimize deterioration of th e separation column, the lipophilic constituents in the acid hydrolysate we re removed by a two-phase partition system of chloroform-methanol-water. Th e inorganic sulfate was quantitatively extracted into the aqueous phase by replacing water with an alkaline buffer. jlr By this method, the concentrat ion of sulfolipids was determined in the kidney of mammals with various bod y mass. Sulfolipids were more concentrated in the kidney of smaller animals , which have higher maximum urine concentrating activity per gram of body m ass, supporting the hypothesis of the function of sulfolipids as an ion bar rier on the luminal surface of renal tubules.