Cellulose Paper Sorptive Extraction (CPSE) Combined with Gas Chromatography–Mass Spectrometry (GC–MS) for Facile Determination of Lorazepam Residues in Food Samples Involved in Drug Facilitated Crimes

Abstract

Reports related to incidences of drug facilitated crimes (DFCs) have notably increased in recently. In such cases, victims report being assaulted or robbed while under the influence of drugs. Lorazepam (LZ) is frequently used in DFCs as it can easily make victims docile owing to its potent numbing effect. Therefore, a straightforward and green analytical method to analyze LZ in spiked food matrices in connection with criminal acts becomes important. The current study reports a simple, green, and high sample throughput analytical method for determining LZ in food and drink matrices commonly encountered in DFCs, based on recently introduced cellulose paper sorptive extraction (CPSE). For the extraction of LZ from food matrices, pristine cellulose paper (CP, commonly used laboratory filter paper) was used as a sorptive medium. Five pieces of CP (1.5″ × 1.5″ each) were dipped into diluted food matrices (cream biscuits and tea) and stirred on a rotary shaker for 30 min at 200 rpm. The CPs were then dried, and the adsorbed LZ was back-extracted into 2 mL of methanol. The extract was then subjected to GC–MS analysis in selected ion monitoring (SIM) mode. Several parameters, including CP size and number, back-extraction solvent type and volume, sample volume, extraction time and stirring speed, pH, ionic strength, elution time and speed, were thoroughly screened and optimized. Under the optimized conditions, the method was found to be linear in the range of 0.2–10 µg·mL−1 (or µg·g−1) with a coefficient of determination (R2) ranging from 0.996–0.998. The limit of detection and limit of quantification for cream biscuits were 0.054 and 0.18 µg·g−1 whereas they were 0.05 and 0.16 µg·mL−1 for tea samples. For all measurements, the relative standard deviations (%RSD) were always below 10%. Two mL of methanol per sample was used during the entire sample preparation process. The greenness of the proposed procedure was evaluated using Analytical Eco-Scale and GAPI greenness assessment tools. Finally, the CPSE–GC–MS method has been applied for the determination of LZ in forensic food samples which were used in DFCs.