Identification of metabolites of 4,4'-methylenedianiline in vascular smooth muscle cells by liquid chromatography-electrospray tandem mass spectrometry.

A capillary liquid chromatography-electrospray tandem mass spectrometry (LC-ES-MS/MS) method was developed for the identification of metabolites of 4,4'-methylenedianiline (diaminodiphenyl methane, (DAPM)) derived from exposure of vascular smooth muscle cells (VSMC) to this compound. The use of precolumn concentration and column switching techniques prior to reversed-phase liquid chromatography coupled online to ES-MS enabled the separation and detection of low-level DAPM and its metabolites in the exposed cell samples. The employed LC-ES-MS method, and further LC-ES-MS/MS analysis enabled the structural assignments for two DAPM metabolites from vascular smooth muscle cells: N-acetyl methylenedianiline (N-acetyl-DAPM) and N,N'-diacetyl methylenedianiline (N,N'-diacetyl-DAPM).