The mass spectrometric behaviors of N-(2-oxopyn-olidin-l-ylmethyD- valine (PMV), N, N-bis(2-oxopyrrolidin-l-ylmethyl)-β-alanine (PMA) and N, N-bis(2-oxopyrrolidin-l-ylmethyl)-leucine (PML) were studied under electrospray ionization condition by multi-stage mass spectrometric (MS~n) experiments. Under this electrospray ionization condition, protonation forms of PMV, PML and PMA were observed, respectively, and their Na~+ and K~+ adducts were also detected. These three compounds followed the fragmentation passway with die preferential sequence relating to the cleavage of C-N bonds, and numerous dimmer and trimmer ions via hydrogen bonding interaction were formed under the experimental condition.

Key words: MASS SPECTROGRAPHY, AMINO ACID, PYRROLIDONE P, VALINE, LEUCINE