Monitoring and quantification on solid support of a by-product formation during peptide synthesis by Tof-SIMS

To evaluate the amount of pyroglutamic acid formation during the synthesis of glutamic acid containing peptides, resin beads were substituted by known amounts of Fmoc-Glu(O'Bu)-Phe-Ala-NH2 and the corresponding side-product Pyr-Phe-Ala-NH2 and directly analyzed by time of flight-secondary ion mass spectrometry. Detection and quantification of pyroglutamic acid was achieved without release of the peptide chains in solution. (C) 1999 Elsevier Science Ltd. All rights reserved.