Evaluation of bumetanide as a matrix for prompt fragmentation matrix-assisted laser desorption/ionization and demonstration of prompt fragmentation/post-source decay matrix-assisted laser desorption/ionization mass spectrometry.

Bumetanide was evaluated as a matrix for prompt fragmentation matrix-assisted laser desorption/ionization (MALDI) experiments on peptides. Both the MALDI mass spectrum and some physical properties of bumetanide were compared with those of some commonly used matrices. Bumetanide was then evaluated for prompt fragmentation MALDI by comparing the prompt fragmentation produced using bumetanide with that for alpha-cyano-4-hydroxycinnamic acid and 2, 5-dihydroxybenzoic acid. Bumetanide was also evaluated for use in a mixed matrix with alpha-cyano-4-hydroxycinnamic acid. A 4 : 1 matrix mixture was found to be useful for the post-source decay analysis of a prompt fragment ion. The prompt fragmentation/post-source decay analysis experiment is demonstrated on a prompt fragment ion from the oxidized b-chain of insulin.