An Approach to Optimizing Parameters of Mass Spectrometric Detection in the Identification of Trace Amounts of Highly Toxic Substances

Abstract

This study describes a procedure for optimizing the following parameters: scanning rate, the duration of selective transition registration (dwell time), and the delay between transitions from one selective transition to another (pause time). The study employed a liquid chromatograph coupled with a triple quadrupole mass spectrometric detector (LC–MS/MS Shimadzu 8050). Chromatographic separation was carried out on a Phenomenex Kinetex C18 reversed-phase column. Mobile phase A consisted of a 0.1% solution of formic acid in water with an addition of 10 mmol/L ammonium formate. Mobile phase B consisted of a 0.1% solution of formic acid in methanol with an addition of 10 mmol/L ammonium formate. The optimal parameters for confirmatory methods were determined: the dwell time of the selective transition was at least 10 ms, the pause time between the transitions was 1 ms, and the scanning rate ranged from 1000 to 5000 scans per second. This procedure was successfully applied to routine chemical-toxicological studies of urine samples with low concentrations of various narcotic and pharmaceutical substances.