The characterization of crude products from solid-phase peptide synthesis by mu-HPLC/fast atom bombardment mass spectrometry.
Crude product mixtures from the solid-phase synthesis of a series of peptides were analyzed by on-line packed, fused silica column mu-HPLC/Continuous Flow Fast Atom Bombardment Mass Spectrometry (mu-HPLC/CF-FABMS). The technique is superior to the direct FAB analysis of crude product mixtures since competitive ionization and suppression effects are not generally observed. Positive correlation between a chromatographic peak and the desired synthetic product may be obtained. An accurate assessment of peptide deprotection can be made without ambiguity arising from the MS fragmentation of the more labile t-butyl and BOC protecting groups used in FMOC-based solid-phase peptide synthesis strategies. mu-HPLC combined with in-line UV detection and MS analysis allows the use of minimum sample and injection volumes, typically 10-50 pmol contained in 0.2-0.5 microliters.