A high-performance liquid chromatographic (HPLC) procedure for the determination and preparation of desmosine (DES) and isodesmosine (IDE), the major cross-links of elastin, has been developed. Hydrolysates of elastin are treated with a SEP-PAK silica-gel small column and then separated on a silica-gel normal phase column using n-propanol-water-25% ammonia (9:3:0.06, v/v/v) followed by detection at 275 nm. The quantitative yields of DES and IDE are 7.98 +/- 0.47 and 6.44 +/- 0.51 (mean +/- S.D., n = 10) mg/g dry weight, respectively, in bovine ligamentum nuchae. Preparations of cross-links are carried out by means of a preparative column (240 mm x 10 mm), using the same solvent system.