A sensitive gas chromatographic method for determination of protein-associated sulfur

A sensitive method for the determination of elemental sulfur bound to serum albumin and other proteins has been devised. The sample is treated with a hexane solution of triphenylphosphine, and the triphenylphosphine sulfide formed is determined by gas chromatography with a flame photometric sulfur detector. The detection limit of the method is 0.3 microM albumin-associated sulfur. Protein-associated sulfur was not detected in plasma from rats or normal human beings, findings that do not support an earlier suggested transport function of serum albumin for sulfur. Significant amounts of protein-associated sulfur, however, were found in certain rat tissues.