BAPTA-AM is the acetoxymethylester of the
calcium chelator BAPTA and has demonstrated efficacy in several animal models of
cerebral ischemia. This paper describes the development of a method for the determination of
BAPTA-AM in rat plasma by liquid chromatography/tandem mass spectrometry. Owing to multiple
ester groups in the structure of
BAPTA-AM, [M + Na](+) was chosen as the analytical ion for quantification of
BAPTA-AM. During the analytical method development, a high percentage of organic
solvent and the addition of an amount of
sodium acetate and
formic acid in the mobile phase were found to favor the sensitivity and reproducibility of [M + Na](+). Poor fragmentation was usually observed in the MS/MS spectra of
sodium adduct
ions. However, abundant and reproducible fragment
ions were observed for the
BAPTA-AM sodium adduct ion, and therefore the traditional selective reaction-monitoring mode was used to further improve the sensitivity of MS detection. Because of the lability of the
ester bond, a combination of
fluoride and
hydrochloric acid was applied to minimize the enzymatic hydrolysis, and
acetonitrile was chosen to avoid the chemical hydrolysis or solvolysis during the sample collection and preparation procedure. On the basis of these studies, a rapid, sensitive and reproducible method for the determination of
BAPTA-AM in rat plasma, using LC/ESI-MS/MS and a simple
protein precipitation procedure, was developed and validated. Also, the present method was successfully applied to the determination of
BAPTA-AM plasma concentrations for pharmacokinetic studies in rats.