Comparative gas chromatography-mass spectrometry bioanalysis of diazepam and its metabolites: nordazepam, temazepam, oxazepam using different ionization in forensic toxicology practice

Abstract

Introduction. Benzodiazepine usage continues to grow, despite strict prescription control. Main reasons are irrational prescribing and designer benzodiazepine drugs [2,3]. Negative ion chemical ionization mass spectrometry (NICI-MS) is “soft” ionization technique and can improve the sensitivity by a factor of several thousand if compared with positive ion electron impact MS detection, especially for the determination of Diazepam, Nordazepam, Oxazepam, Temazepam with electronegative moieties, such as halogen atom in the xenobiotic itself. Materials and methods. Subject of study – the drug-free urine spiked with stock standards of drugs. The concentration of internal standards oxazepam-D5, fludiazepam, and clonazepam-D4 for these studies was 200 ng/ml. Equipment - AGILENT TECHNOLOGIES-7890A gas chromatograph coupled to a detector 5975C NCI-MS and SHIMADZU GCMS-QP2010 Ultra. Analysis was done according to literature source [1]. Results and discussion. Total chromatographic analysis time was 4.9 min. in GC-NICI-MS and 17 min. in GC-EI-MS analysis. Analysis for diazepam carried out with GC-EI-MS had 68 ng mL-1 limit of detection (LOD) and 340 ng mL-1 limit of quantification (LOQ), while analysis with GC-NICI-MS had 1,4 ng mL-1 and 4,2 ng mL-1.