Screening procedure for the analysis of distigmine bromide in serum by high-performance liquid chromatography–electrospray ionization mass spectrometry

A screening procedure was developed for the identification and quantification of distigmine bromide in serum samples by using liquid chromatography (LC)–electrospray ionization (ESI)-mass spectrometry (MS). In this method, distigmine bromide was analyzed in 0.5 mL serum by using pancuronium bromide as the internal standard, and gradient elution was performed using a reversed-phase column and a mixture of 10 mM-ammonium formate and methanol as the mobile phase. A highly sensitive assay could be performed with simple solid phase extraction using a cation exchange cartridge column by carrying out selected ion monitoring analysis in the positive ion detection mode. The procedure was validated in terms of linearity (0.997 < r2 < 0.999 for concentrations ranging from 5 to 250 ng/mL), extraction recovery (83.0% to 89.3%, n = 5), and detection limit (S/N ratio, >3 at 2.5 ng/mL). The inter- and intra-day precisions (coefficient of variation; CV%) were <8.5% and <9.7%, respectively. The analytes were evaluated for stability and were found to be stable in serum for 1 week at 4 °C and 4 weeks at −30 °C, and successfully applied to in the analysis of two overdose cases. This method is sensitive and useful for the detection, quantification, and confirmation of distigmine bromide in serum.