Rapid Drop-Volume Electrochemical Detection of the “Date Rape” Drug Flunitrazepam in Spirits Using a Screen-Printed Sensor in a Dry-Reagent Format

Abstract

Flunitrazepam is an extremely potent benzodiazepine sedative which is associated with “drug-facilitated sexual assault” when administered within an alcoholic drink. This work describes a simple electrochemical method for on-site rapid detection of flunitrazepam in untreated spirits (whiskey, vodka and gin) using a single-use screen-printed sensor (featuring graphite working and auxiliary electrodes and an Ag/AgCl reference electrode) in a dry reagent format. Analysis was performed by placing a drop of sample on the sensor, which was previously coated with dry KCl, and recording selected reduction/oxidation peaks of the target compound in a cyclic voltammetry scan. The limit of quantification of flunitrazepam was at the sub-mg L−1 range. The between-sensor % relative standard deviation of the analytically useful reduction peak in a solution containing 11.4 mg L−1 flunitrazepam was 9.8% (n = 5). Quantification was performed using calibration curves constructed from pooled samples spiked with flunitrazepam with relative errors <15%. The main advantages of the methodology are that it involves no sample pretreatment (such as deoxygenation, extraction or reagent(s) addition) and requires only drop-sized volumes of the sample, thus facilitating rapid on-site screening using portable equipment.

Interpol Review of Drug Analysis 2019-2022

“…2019 hybrid electrocatalyst modified SPCE was developed for the determination of flunitrazepam [ 111 ]; Lab-on-a-screen-printed electrochemical cell for drop-volume voltammetric screening and detection of flunitrazepam to a wide range of untreated and undiluted spiked samples (Pepsi cola (R), Vodka, Whisky, Tequila, Gin, and Rum) [ 112 ]; 2020 electrochemical sensor for on-site detection of flunitrazepam in spirits [ 113 ]; electrochemical sensor for trace analysis of flunitrazepam in aqueous solutions [ 114 ]; 2021 carbon paste electrode for electrochemical determination of flunitrazepam [ 115 ]; electrochemical sensor for detection of Rohypnol/flunitrazepam in drinks [ 116 ]; miniaturized sensing device for the determination of flunitrazepam in carbonated soft drinks, energy drink, and malt beverage [ 117 ]…”

Wearable Electronic Finger for Date Rape Drugs Screening: From “Do-It-Yourself” Fabrication to Self-Testing

“…Among the most commonly used DRDs are flunitrazepam (FLU), scopolamine (SCO), and ketamine (KET). − , FLU belongs to the benzodiazepine family and is legally prescribed for insomnia treatment under different trade names (Rohypnol, Vulbegal, Hipnosedon, etc. ), while it is colloquially known as “Roofies” or “Mexican Valium”. − SCO (also known as hyoscine) is a tropane alkaloid extensively used in medicine (trade name: Buscopan) because of its strong parasympatholytic, anticholinergic, and antiemetic actions, while it can cause box lock amnesia. “Burundanga” is the slang word for SCO.…”

“…Indeed, different electrochemical sensors have been applied to DRDs and analgesics determination in spirits. More specifically, a boron-doped diamond electrode was used for the detection of SCO in diluted alcoholic beverages; a paper-based analytical device (PAD) modified with zeolites and graphene-oxide was applied to the determination of KET in reagent-treated alcoholic drinks; and a pencil-drawn electrochemical PAD was used to determine analgesics in diluted whiskey samples. , Regarding the determination of FLU, five carbon-based screen-printed electrodes (SPE) (bare or modified with ion-sensing polymeric membrane) were applied in deoxygenated or diluted alcoholic drinks, and a graphite SPE modified with Fe nanoparticles and with glucose oxidase/glucose was used to determine FLU in untreated spirits. − On the other hand, wearable devices have emerged as a major technological breakthrough mainly for the monitoring of the wearer’s health status and recently have made their first steps to the screening of drugs of abuse. − The few existing wearable electrochemical interfaces for drug abuse monitoring include a screen-printed ring-based sensor for the detection of Δ 9 -tetrahydrocannabinol and alcohol and a screen-printed glove-based sensor for fentanyl and cocaine. − However, all these devices are not directly accessible to end users, as their fabrication requires trained personnel, centralized laborious multistep processes (such as screen-printing), and modification steps. In addition, existing DRDs sensors are mainly intended for single-drug detection using assays requiring addition of reagents and sample pretreatment and thus are not suitable for rapid on-site self-analysis.…”