A new rapid method for the identification of reducible collagen cross-links in small tissue samples.

A normal-phase high-pressure liquid-chromatography system was used with amino-propyl-bonded silica as the column packing in order to resolve amino acids, reduced amino acid derivatives and reduced cross-links of collagen. The method utilized a solvent system comprising acetonitrile and 10 mM-potassium phosphate buffer, pH 4.3, as described by Schuster [(1980) Anal. Chem. 52, 617-620]. With modifications to the original gradient elution it was possible to resolve fully the radiolabelled components of reduced collagen in one run of less than 80 min. The method is very sensitive, and small biopsy samples can readily be investigated. Although solute retention times gradually decreased with repeated use, little loss of resolution of the reducible cross-links of collagen occurred during a 30-day trial period.