A sensitive and convenient method for the simultaneous determination of several of the compounds involved in the biosynthesis of penicillin and cephalosporin is described. The method involves derivatization with a chiral fluorogen ( o -phthaldialdehyde with an optically active thiol N -acetyl- l -cysteine), followed by high-performance liquid chromatography on a reverse-phase column as described by Aswad (D. W. Aswad, 1984, Anal. Biochem. 137 , 405–409) . With an analysis time of 1 h it was possible to determine simultaneously most of the common l -amino acids, l - and d -α-aminoadipic acid, l - and d -valine, δ-( l -α-aminoadipyl)- l -cysteine (AC), δ-( l -α-aminoadipyl)- l -cysteinyl- d -valine (ACV), glutathione, isopenicillin N, penicillin N, desacetoxycephalosporin C, desacetylcephalosporin C, and cephalosporin C. Using o -phthaldialdehyde alone it was possible to determine specifically the thiol-containing peptides AC, ACV, and glutathione.
