Derivatization Reagent for LC-ESI-MS

Higashi et al. have developed 1-(5-Fluoro-2,4-dinitrophenyl)-4-methylpiperazine (1) which can be used as a derivatization reagent for LC-ESI-MS, and is useful for the analysis of hydroxysteroids. For example, 1 reacts rapidly with the phenolic hydroxy group in estradiol to give 3-O-[2,4-dinitro-5-(4-methylpiperazino)phenylestradiol. Then subsequent quaternarization of the piperazine amino group with methyl iodide affords a positively-charged derivative which provides more than 2000-fold higher sensitivity compared to the original estradiol in LC-ESI-MS determination. Higashi et al. have quantified the amount of estrogens in pregnant woman serum, which is clinically important for the diagnosis of the fetoplacental function, with high precision by utilizing this procedure.