Supramolecular Solvent Extraction-Gas Chromatography-Tandem Mass Spectrometry for Detection of Benzodiazepines in Urines

Abstract

Objective To establish a method using supramolecular solvent and gas chromatography-tandem mass spectrometry （GC-MS/MS） to analyze 9 benzodiazepines in urines. Methods Urine samples containing 9 benzodiazepines reference substance were subjected to liquid-liquid extractions with supramolecular solvent, which consisted of tetrahydrofuran and 1-hexanol. The solvent layer was evaporated to dryness by stream of nitrogen. The residue was reconstituted with methanol, and GC-MS/MS analysis was performed on it. The way of data collection was multiple reaction monitoring （MRM） mode; internal standard method was employed for quantification. Results In urine samples, when the range of mass concentration was 1- 100 ng/mL for diazepam, midazolam, flunitrazepam and clozapine, 5- 100 ng/mL for lorazepam and alprazolam, 2-100 ng/mL for nitrazepam and clonazepam, and 0.2-100 ng/mL for estazolam, respectively, good linearities were obtained, correlation coefficients were 0.999 1-0.999 9, the lower limits of the quantifications ranged from 0.2 to 5 ng/mL, the extraction recovery rates were 81.12%- 99.52%. The intra-day precision［relative standard deviation（RSD）］and accuracy（bias）were lower than 9.86% and 9.51%, respectively; the inter-day precision（RSD）and accuracy（bias）were lower than 8.74% and 9.98% , respectively. Nine drugs in urine samples showed good stability at ambient temperature and -20 ℃ within 15 days. The mass concentrations of alprazolam in urine samples obtained from 8 volunteers who took alprazolam tablets orally within 8-72 h after ingestions ranged from 6.54 to 88.28 ng/mL.

Keywords

• forensic toxicology; gas chromatography-tandem mass spectrometer; benzodiazepines; supramolecular solvent; urin