Liquid chromatography-tandem mass spectrometry analysis of nitrogen mustard degradation products after derivatization with benzoylimidazole

Nitrogen mustards are highly toxic compounds and strictly controlled by the Chemical Weapons Convention. When those agents are used, exposure must be confirmed by analyzing biological samples from victims to allow prompt medication and reduction of secondary damage. In this study, a derivatization-liquid chromatography (LC)-tandem mass spectrometry (MS/MS) method to analyze nitrogen mustard degradation products (ethanol- amines; EAs) in human urine was developed. Benzoylimidazole (BzI) was used as a derivatization reagent, and two highly hydrophilic EAs (methyldiethanolamine and ethyldiethanolamine) were analyzed by using a reversed-phase column with sufficient retention. For urine samples, after solid-phase extraction with cation exchange cartridge and derivatization, EAs were analyzed at low limits of detection (5 ng/mL). The calibration curves had a wide linear range (50-1000 ng/mL), and the quantitation results were sufficient for screening. Compared with our previous derivatization-LC-MS/MS method using pentafluorobenzoyl chloride as a derivatization reagent and hydrophilic interaction liquid chromatography (HILIC)-MS/MS method, not only the limits of detection but also the operability and throughput were improved. The performance of the newly developed derivatization reagent was also evaluated using density functional theory (DFT) calculations.