Time-of-flight mass spectrometry (TOF-MS) exact mass database for benzodiazepine screening

Abstract Time-of-flight mass spectrometry coupled with liquid chromatography (TOF-MS) has been developed for screening and determination of benzodiazepines with an exact mass database. Benzodiazepines display similar chemical structures and molecular weights, and thus show similar mass spectra and protonated molecule ions. Discrimination of mass spectrometry at low resolving power using single liquid chromatography mass spectrometry (LC–MS) is commonly difficult. TOF-MS analysis was performed using a 1100 TOF (Agilent Technologies) equipped with a Zorbax C18 Extend column. Purine and fluorine compound solution was always introduced into the ion source, and real-time mass adjusting was performed. Specimens were prepared utilizing the liquid–liquid extraction procedure with 1-chlorobutane. Benzodiazepines are widely used in medical practice in Japan, and data acquired from TOF-MS measurements of 41 benzodiazepines, including active metabolites, were used to create an exact mass database. This database comprised molecular formulae, calculated exact masses and retention times. Calibrations were also included in a database. Precision for the 41 drugs was considered sufficient for quantitative analysis. In analysis of samples from patient who had taken ⩾2 benzodiazepines, selectivity was improved using the TOF-MS exact mass database. TOF-MS is effective for forensic toxicology in discriminating between benzodiazepines with similar structure and metabolites.