HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY IONSPRAY MASS-SPECTROMETRY OF N-ETHYLMALEIMIDE AND ACRYLIC-ACID ESTER DERIVATIVES FOR BIOANALYSIS OF THIOL COMPOUNDS

High performance liquid chromatography/ionspray mass spectra of N-ethylmaleimide (NEM) and acrylate derivatives of the sulfhydryl compound BMS186716 exhibited a variety of fragmentation patterns, in positive- or negative-ion mode, providing a wide choice of conditions for developing a bioanalytical method based on selected-ion monitoring. Because the NEM derivative gave two chromatographic peaks (due to two diastereomers) whereas the acrylate derivative gave a single peak, the acrylate derivatization was chosen for further investigations. While BMS186716 in blood or plasma was extremely unstable, the compound could be stabilized by adding methyl acrylate (MA) to the biological matrix, owing to instantaneous reaction to form the stable BMS186716-MA derivative. This stabilization scheme is being investigated for developing a sensitive bioanalytical liquid chromatographic/mass spectrometric method for BMS186716.