Measurement of serum glycosaminoglycans by laser nephelometry

A simple, sensitive micromethod for the assay of serum hyaluronic acid and chondroitin sulphates is presented. The method is based on the binding of the quaternary ammonium salt, cetylpyridinium chloride (CPC) to serum polyanions, and quantitation of the complexes by laser nephelometry. Measurement of the CPC complexes in serum before and after digestion with specific enzymes enables quantitation of hyaluronic acid and chondroitin sulphates in less than 100 μl serum. Using this technique, hyaluronic acid is detectable in a small number of normal human sera at concentrations up to 4 mg/l, and chondroitin sulphates are consistently present at concentrations ranging from 2 to 25 mg/l.