Development of an ultra-sensitive electrochemical sensor for Δ9-tetrahydrocannabinol (THC) and its metabolites using carbon paper electrodes

Recent reports on the sensing strategy and the On-site detection of illegal drugs

In this review, works on the on-site detection of illegal drugs in recent years are summarised and discussed, most of which were published within the past five years. The detection methods are categorised as colourimetric, fluorescence, Raman spectrometry, ion mobility spectrometry, electrochemistry, and mass spectrometry. Also, strategies that are possibly suitable for on-site detection and the actual instrumentation to be used in the field are listed.

An electrochemical approach for the prediction of Δ9-tetrahydrocannabinolic acid and total cannabinoid content in Cannabis sativa L

Two electrochemical sensors are proposed here for the first time for the fast screening of cannabinoids in Cannabis sativa L. plant material (inflorescences). The accurate control of cannabinoid content is important for discriminating between recreational, i.e. illegal, and fibre-type C. sativa samples, which differ mainly according to the amount of Δ9-tetrahydrocannabinol (Δ9-THC) and Δ9-tetrahydrocannabinolic acid (Δ9-THCA). Two screen printed electrodes obtained using different electrode materials were tested for the analysis of extracts from recreational and fibre-type C. sativa and their performance was compared with a consolidated method based on high-performance liquid chromatography (HPLC). The voltammetric responses recorded in the different samples reflected the compositional differences of the recreational and fibre-type extracts in accordance with the results of HPLC analyses. Moreover, the quantification of Δ9-THCA and the total cannabinoid content on the basis of the intensity of the peaks of the voltammograms was possible through a simple and fast electrochemical procedure.

Nitrazepam and 7-aminonitrazepam studied at the macroscopic and microscopic electrified liquid-liquid interface

Two benzodiazepine type drugs, that is, nitrazepam and 7-aminonitrazepam, were studied at the electrified liquid-liquid interface (eLLI). Both drugs are illicit and act sedative in the human body and moreover are used as date rape drugs. Existence of the diazepine ring in the concerned chemicals structure and one additional amine group (for 7-aminonitrazepam) allows for the molecular charging below their pKa values, and hence, both drugs can cross the eLLI interface upon application of the appropriate value of the Galvani potential difference. Chosen molecules were studied at the macroscopic eLLI formed in the four electrode cell and microscopic eLLI formed within a microtip defined as the single pore having 25 μm in diameter. Microscopic eLLI was formed using only a few μL of the organic and the aqueous phase with the help of a 3D printed cell. Parameters such as limit of detection and voltammetric detection sensitivity are derived from the experimental data. Developed methodology was used to detect nitrazepam in pharmaceutical formulation and both drugs (nitrazepam and 7-aminonitrazepam) in spiked biological fluids (urine and blood).

An electrochemical aptasensor for Δ9-tetrahydrocannabinol detection in saliva on a microfluidic platform

We present a novel "on-off", cost-effective, rapid electrochemical aptasensor combined with a microfluidics cartridge system for the detection of Δ⁹-THC (Δ⁹-tetrahydrocannabinol) in human saliva via differential pulse voltammetry. The assay relied on the competitive binding between the Δ⁹-THC and a soluble redox indicator methylene blue, using an aptamer selected via FRELEX. We found that the aptasensor can detected 1 nM of Δ⁹-THC in PBS in a three-electrode cell system, while the sensitivity and both the dissociation constant (K_d) and association constant (K_b) were dependent on the aptamer density. The aptamer also showed great affinity towards Δ⁹-THC when tested against cannabinol and cannabidiol. The same limit of detection of 1 nM in PBS was achieved in small volume samples (∼60 μL) using the aptamer-modified gold screen-printed electrodes combined with the microfluidic cartridge setup, however, the presence of 10% raw human saliva had a negative effect which manifested in a 10-fold increase in the LOD due to interfering elements. Filtering the saliva, improved the tested volume to 50% and the LOD to 5 nM of Δ⁹-THC which is lower than the concentrations associated with impairment (6.5-32 nM). The aptasensor showed a good storage capability up to 3 days, however, the reusability significantly dropped from 10 cycles (freshly prepared) to 5 cycles. The results clearly demonstrate the feasibility of the aptasensor platform with the microfluidics chamber towards a point-of-care testing application for the detection of Δ⁹-THC in saliva.

Heroin detection in a droplet hosted in a 3D printed support at the miniaturized electrified liquid-liquid interface

Simple sensing protocols for the detection of illicit drugs are needed. Electrochemical sensing is especially attractive in this respect, as its cost together with the analytical accuracy aspires to replace still frequently used colorimetric tests. In this work, we have shown that the interfacial transfer of protonated heroin can be followed at the electrified water-1,2-dichloroethane interface. We have comprehensively studied the interfacial behavior of heroin alone and in the presence of its major and abundant cutting agents, caffeine and paracetamol. To maximally increase developed sensing protocol applicability we have designed and 3D printed a platform requiring only a few microliters of the aqueous and the organic phase. The proposed sensing platform was equipped with a cavity hosting a short section of Ag/AgCl electrode, up to 20 µL of the aqueous phase and the end of the micropipette tip being used as a casing of a fused silica capillary having 25 µm as the internal pore diameter. The volume of the organic phase was equal to around 5 µL and was present inside the micropipette tip. We have shown that under optimized conditions heroin can be detected in the presence of caffeine and paracetamol existing in a sample with 10,000 times excess over the analyte of interest. The calculated limit of detection equal to 1.3 µM, linear dynamic range spanning to at least 50 µM, good reproducibility, and very low volume of needed sample is fully in line with forensic demands.

Portable biosensors for rapid on-site determination of cannabinoids in cannabis, a review

Recent studies highlight the therapeutic virtues of cannabidiol (CBD). Furthermore, due to their molecular enriched profiles, cannabis inflorescences are biologically superior to a single cannabinoid for the treatment of various health conditions. Thus, there is flourishing demand for Cannabis sativa varieties containing high levels of CBD. Additionally, legal regulations around the world restrict the cultivation and consumption of tetrahydrocannabinol (THC)-rich cannabis plants for their psychotropic effects. Therefore, the use of cannabis varieties that are high in CBD is permitted as long as their THC content does not exceed a low threshold of 0.3%-0.5%, depending on the jurisdiction. These chemovars are legally termed 'hemp'. This controlled cannabinoid requirement highlights the need to detect low levels of THC, already in the field. In this review, cannabis profiling and the existing methods used for the detection of cannabinoids are firstly evaluated. Then, selected valuable biosensor technologies are discussed, which suggest portable, rapid, sensitive, reproducible, and reliable methods for on-site identification of cannabinoids levels, mainly THC. Recent cutting-edge techniques of promising potential usage for both cannabis and hemp analysis are identified, as part of the future cultivation and agricultural improvement of this crop.

Affinity Assays for Cannabinoids Detection: Are They Amenable to On-Site Screening?

Roadside testing of illicit drugs such as tetrahydrocannabinol (THC) requires simple, rapid, and cost-effective methods. The need for non-invasive detection tools has led to the development of selective and sensitive platforms, able to detect phyto- and synthetic cannabinoids by means of their main metabolites in breath, saliva, and urine samples. One may estimate the time passed from drug exposure and the frequency of use by corroborating the detection results with pharmacokinetic data. In this review, we report on the current detection methods of cannabinoids in biofluids. Fluorescent, electrochemical, colorimetric, and magnetoresistive biosensors will be briefly overviewed, putting emphasis on the affinity formats amenable to on-site screening, with possible applications in roadside testing and anti-doping control.

Engineered Nucleotide Chemicapacitive Microsensor Array Augmented with Physics-Guided Machine Learning for High-Throughput Screening of Cannabidiol

The recent legalization of cannabidiol (CBD) to treat neurological conditions such as epilepsy has sparked rising interest across global pharmaceuticals and synthetic biology industries to engineer microbes for sustainable synthetic production of medicinal CBD. Since the process involves screening large amounts of samples, the main challenge is often associated with the conventional screening platform that is time consuming, and laborious with high operating costs. Here, a portable, high-throughput Aptamer-based BioSenSing System (ABS³ ) is introduced for label-free, low-cost, fully automated, and highly accurate CBD concentrations' classification in a complex biological environment. The ABS³ comprises an array of interdigitated microelectrode sensors, each functionalized with different engineered aptamers. To further empower the functionality of the ABS³ , unique electrochemical features from each sensor are synergized using physics-guided multidimensional analysis. The capabilities of this ABS³ are demonstrated by achieving excellent CBD concentrations' classification with a high prediction accuracy of 99.98% and a fast testing time of 22 µs per testing sample using the optimized random forest (RF) model. It is foreseen that this approach will be the key to the realistic transformation from fundamental research to system miniaturization for diagnostics of disease biomarkers and drug development in the field of chemical/bioanalytics.

Advances of Drugs Electroanalysis Based on Direct Electrochemical Redox on Electrodes: A Review

The strong development of mankind is inseparable from the proper use of drugs, and the electroanalytical research of drugs occupies an important position in the field of analytical chemistry. This review mainly elaborates the research progress of drugs electroanalysis based on direct electrochemical redox on various electrodes for the recent decade from 2011 to 2021. At first, we summarize some frequently used electrochemical data processing and electrochemical mechanism research derivation methods in the literature. Then, according to the drug therapeutic and application/usage purposes, the research progress of drugs electrochemical analysis is classified and discussed, where we focus on drugs electrochemical reaction mechanism. At the same time, the comparisons of electrochemical sensing performance of the drugs on various electrodes from recent studies are listed, so that readers can more intuitively compare and understand the electroanalytical sensing performance of each modified electrode for each of the drug. Finally, this review discusses the shortcomings and prospects of the drugs electroanalysis based on direct electrochemical redox research.

Recent advances in electrochemical sensor technologies for THC detection-a narrative review

Background

Δ⁹-tetrahydrocannabinol (THC) is the main psychoactive component and one of the most important medicinal compounds in cannabis. Whether in human body fluids and breath or in laboratory and field samples, rapid and easy detection of THC is crucial. It provides insights into the impact of THC on human organism and its medicinal benefits, it guides the cannabis growers to determine different stages of the growth of the plant in the field, and eventually it helps scientists in the laboratory to assure the quality of the products and determine their potency or better understand the product development procedures. The significance of fast THC detection in forensic analysis also cannot be overlooked. Electrochemical sensor technologies are currently in the focus of attention for fast, easy, and low-cost detection of THC.

Method

In this work, we review the recent advances in sensor technologies developed for the purpose of fast and accurate THC detection. The research works performed mostly in the past decade and those detecting THC directly without any derivatization were the main target of this review. The scope of this narrative review was the reports on detecting THC in synthetic samples and plants as well as oral fluid.

Results

Electrochemical sensor technologies are sensitive enough and have the potential for fast, easy, and low-cost detection of THC for roadside testing, THC trending in growing cannabis plants, THC product development and formulation for medical purposes, etc., and they can provide an alternative for costly chromatography and mass spectrometry-based methods.

Conclusion

The main challenges facing these sensors, however, are nonspecific interaction and the interference of compounds and species from the matrix. Special requirement for storing sensors modified with antibodies or proteins is another challenge in this field. Preparing long-lasting and reusable sensors is a field worthy of attention.

Development of an Electrochemical Sensor Using a Modified Carbon Paste Electrode with Silver Nanoparticles Capped with Saffron for Monitoring Mephedrone

Mephedrone, also known as 4-methylmethcathinone, is growing into a prominent recreational drug for young people. When it came to detecting mephedrone, limited efforts were made using electrochemical sensors. As a result, this application depicts the fabrication of a new, sensitive, selective, and economical electrochemical sensor capable of detecting mephedrone by using silver nanoparticles capped with saffron produced through electropolymerization to modify carbon paste electrodes (CPEs). Silver nanoparticles (AgNPs) were capped with saffron (AgNPs@Sa) using a green method. AgNPs@Sa were studied using electron scanning microscopy (SEM) and UV-vis spectroscopy. The sensor was evaluated under the optimum condition to determine its analytical features. The results showed that this procedure had a wide linear range, low detection limit and sufficient reproducibility. Furthermore, the sensor posed sufficient stability. Moreover, it was applied in the determination of mephedrone in urine samples, showing the potential applicability of this electrochemical sensor in real sample analysis.

A biomolecule-free electrochemical sensing approach based on a novel electrode modification technique: Detection of ultra-low concentration of Δ⁹-tetrahydrocannabinol in saliva by turning a sample analyte into a sensor analyte

Cannabis is currently one of the most consumed drugs in many countries. Δ⁹-tetrahydrocannabinol (THC) is the principal psychoactive component of this drug and is present in saliva after consumption. This paper reports a novel biomolecule-free electrochemical approach to detect an ultra-low level of THC in saliva using modified electrodes with molecules of the same analyte (THC) that are detected later via square wave voltammetry. The results from this research revealed that the electrodeposition of THC on the working electrode (sensor analyte) could highly enhance the limit of detection by improving the affinity of the THC molecules present in the sample (sample analyte) to the sensing electrode surface. Detailed descriptions about the optimization of the sensor and its performance in simple media, such as PBS, and complex media, such as simulated and real saliva, are provided. This novel and yet simple electrochemical-based sensing strategy allowed for a low limit of detection of 1.6 ng/mL THC in simulated and real saliva, distinguishing concentrations ranging from 2 to 25 ng/mL, making this technology viable for a real-world application such as roadside testing.

Advances in Medical Wearable Biosensors: Design, Fabrication and Materials Strategies in Healthcare Monitoring

In the past decade, wearable biosensors have radically changed our outlook on contemporary medical healthcare monitoring systems. These smart, multiplexed devices allow us to quantify dynamic biological signals in real time through highly sensitive, miniaturized sensing platforms, thereby decentralizing the concept of regular clinical check-ups and diagnosis towards more versatile, remote, and personalized healthcare monitoring. This paradigm shift in healthcare delivery can be attributed to the development of nanomaterials and improvements made to non-invasive biosignal detection systems alongside integrated approaches for multifaceted data acquisition and interpretation. The discovery of new biomarkers and the use of bioaffinity recognition elements like aptamers and peptide arrays combined with the use of newly developed, flexible, and conductive materials that interact with skin surfaces has led to the widespread application of biosensors in the biomedical field. This review focuses on the recent advances made in wearable technology for remote healthcare monitoring. It classifies their development and application in terms of electrochemical, mechanical, and optical modes of transduction and type of material used and discusses the shortcomings accompanying their large-scale fabrication and commercialization. A brief note on the most widely used materials and their improvements in wearable sensor development is outlined along with instructions for the future of medical wearables.

A rapid assay provides on-site quantification of tetrahydrocannabinol in oral fluid

[Figure: see text].

An Electrochemical Sensor Based on Amino Magnetic Nanoparticle-Decorated Graphene for Detection of Cannabidiol

For detection of cannabidiol (CBD)—an important ingredient in Cannabis sativa L.—amino magnetic nanoparticle-decorated graphene (Fe₃O₄-NH₂-GN) was prepared in the form of nanocomposites, and then modified on a glassy carbon electrode (GCE), resulting in a novel electrochemical sensor (Fe₃O₄-NH₂-GN/GCE). The applied Fe₃O₄-NH₂ nanoparticles and GN exhibited typical structures and intended surface groups through characterizations via transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), vibrating sample magnetometer (VSM), and Raman spectroscopy. The Fe₃O₄-NH₂-GN/GCE showed the maximum electrochemical signal for CBD during the comparison of fabricated components via the cyclic voltammetry method, and was systematically investigated in the composition and treatment of components, pH, scan rate, and quantitative analysis ability. Under optimal conditions, the Fe₃O₄-NH₂-GN/GCE exhibited a good detection limit (0.04 μmol L⁻¹) with a linear range of 0.1 μmol L⁻¹ to 100 μmol L⁻¹ (r² = 0.984). In the detection of CBD in the extract of C. sativa leaves, the results of the electrochemical method using the Fe₃O₄-NH₂-GN/GCE were in good agreement with those of the HPLC method. Based on these findings, the proposed sensor could be further developed for the portable and rapid detection of natural active compounds in the food, agricultural, and pharmaceutical fields.

Delta-9-tetrahydrocannabinol (Δ9-THC) sensing using an aerosol jet printed organic electrochemical transistor (OECT)

Recreational use of marijuana/cannabis was legalized in Canada in 2018 and has been decriminalized in several other countries; however, the detection of impairment has remained elusive for law enforcement. The psychoactive ingredient in cannabis, delta-9-tetrahydrocannabinol (Δ9-THC), can be detected in saliva and be correlated well with the intake of cannabis. Organic electrochemical transistors (OECTs) have been used for a variety of biosensing applications like glucose, pH, ions, etc. In this work, we demonstrate the use of unfunctionalized OECTs for the detection of Δ9-THC down to 0.1 nM and 1 nM diluted in DI water and synthetic saliva buffer, respectively. These OECTs have been aerosol jet printed entirely with PEDOT:PSS as the channel material. Using a platinum gate coupled with an aerosol jet printed OECT, Δ9-THC concentration can be detected due to its oxidation reaction at the gate. These results were consistent with cyclic voltammetry measurements of Δ9-THC using Pt as the working and counter electrode. Utilizing these OECT based sensors, we have achieved high sensitivity of detection of Δ9-THC in the range from 0.1 nM to 5 μM. These OECT based Δ9-THC sensors demonstrate less than 3% error indicating good repeatability which is averaged over 15 measurements on multiple devices.

Antioxidant function of phytocannabinoids: Molecular basis of their stability and cytoprotective properties under UV-irradiation

In this contribution, a comprehensive study of the redox transformation, electronic structure, stability and photoprotective properties of phytocannabinoids is presented. The non-psychotropic cannabidiol (CBD), cannabigerol (CBG), cannabinol (CBN), cannabichromene (CBC), and psychotropic tetrahydrocannabinol (THC) isomers and iso-THC were included in the study. The results show that under aqueous ambient conditions at pH 7.4, non-psychotropic cannabinoids are slight or moderate electron-donors and they are relatively stable, in the following order: CBD > CBG ≥ CBN > CBC. In contrast, psychotropic Δ⁹-THC degrades approximately one order of magnitude faster than CBD. The degradation (oxidation) is associated with the transformation of OH groups and changes in the double-bond system of the investigated molecules. The satisfactory stability of cannabinoids is associated with the fact that their OH groups are fully protonated at pH 7.4 (pKa is ≥ 9). The instability of CBN and CBC was accelerated after exposure to UVA radiation, with CBD (or CBG) being stable for up to 24 h. To support their topical applications, an in vitro dermatological comparative study of cytotoxic, phototoxic and UVA or UVB photoprotective effects using normal human dermal fibroblasts (NHDF) and keratinocytes (HaCaT) was done. NHDF are approx. twice as sensitive to the cannabinoids' toxicity as HaCaT. Specifically, toxicity IC₅₀ values for CBD after 24 h of incubation are 7.1 and 12.8 μM for NHDF and HaCaT, respectively. None of the studied cannabinoids were phototoxic. Extensive testing has shown that CBD is the most effective protectant against UVA radiation of the studied cannabinoids. For UVB radiation, CBN was the most effective. The results acquired could be used for further redox biology studies on phytocannabinoids and evaluations of their mechanism of action at the molecular level. Furthermore, the UVA and UVB photoprotectivity of phytocannabinoids could also be utilized in the development of new cannabinoid-based topical preparations.

Electrochemical sensing: A prognostic tool in the fight against COVID-19

The COVID-19 pandemic has devastated the world, despite all efforts in infection control and treatment/vaccine development. Hospitals are currently overcrowded, with health statuses of patients often being hard to gauge. Therefore, methods for determining infection severity need to be developed so that high-risk patients can be prioritized, resources can be efficiently distributed, and fatalities can be prevented. Electrochemical prognostic biosensing of various biomarkers may hold promise in solving these problems as they are low-cost and provide timely results. Therefore, we have reviewed the literature and extracted the most promising biomarkers along with their most favourable electrochemical sensors. The biomarkers discussed in this paper are C-reactive protein (CRP), interleukins (ILs), tumour necrosis factor alpha (TNFα), interferons (IFNs), glutamate, breath pH, lymphocytes, platelets, neutrophils and D-dimer. Metabolic syndrome is also discussed as comorbidity for COVID-19 patients, as it increases infection severity and raises chances of becoming infected. Cannabinoids, especially cannabidiol (CBD), are discussed as a potential adjunct therapy for COVID-19 as their medicinal properties may be desirable in minimizing the neurodegenerative or severe inflammatory damage caused by severe COVID-19 infection. Currently, hospitals are struggling to provide adequate care; thus, point-of-care electrochemical sensor development needs to be prioritized to provide an approximate prognosis for hospital patients. During and following the immediate aftermath of the pandemic, electrochemical sensors can also be integrated into wearable and portable devices to help patients monitor recovery while returning to their daily lives. Beyond the COVID-19 pandemic, these sensors will also prove useful for monitoring inflammation-based diseases such as cancer and cardiovascular disease.

Development of an electrochemical sensor based on carbon black for the detection of cannabidiol in vegetable extracts

A glassy carbon electrode chemically modified with a carbon black coating is proposed here for the rapid and portable determination of cannabidiol (CBD) in a commercial Cannabis seed oil and in fibre-type Cannabis sativa L. leaves.

Electrochemical Oxidation of Δ9-Tetrahydrocannabinol: A Simple Strategy for Marijuana Detection

Recently, it has been estimated that nearly 200 million people use marijuana with growing usage being attributed to the legalization and decriminalization of the drug around the world. A concerning implication of increased marijuana use is the alarming number of individuals who report driving under the influence of the drug, which has prompted the development of detection technologies. An electrochemical-based detection technology, akin to how the alcohol breathalyzer functions, would provide an attractive solution to this growing societal problem. The first step toward this goal is to develop a reaction that converts Δ9-tetrahydrocannabinol (Δ9-THC), the primary psychoactive substance in marijuana, to a derivative with diagnostic spectroscopic changes. We report the development of a mild electrochemical method for the oxidation of Δ9-THC to its corresponding p-quinone isomer. The photophysical and electrochemical properties of the resultant quinone show a dramatic shift in comparison to Δ9-THC. This simple protocol provides the foundation for the development of an electrochemical-based marijuana breathalyzer.

Electrochemical Sensing of Cannabinoids in Biofluids: A Noninvasive Tool for Drug Detection

Cannabinoid sensing in biofluids provides great insight into the effects of medicinal cannabis on the body. The prevalence of cannabis for pain management and illicit drug use necessitates knowledge translation in cannabinoids. In this Review, we provide an overview of the current detection methods of cannabinoids in bodily fluids emphasizing electrochemical sensing. First, we introduce cannabinoids and discuss the structure and metabolism of Δ⁹-THC and its metabolites in relation to blood, urine, saliva, sweat, and breath. Next, we briefly discuss lab based techniques for cannabinoids in biofluids. While these techniques are highly sensitive and specific, roadside safety requires a quick, portable, and cost-effective sensing method. These needs motivated a comprehensive review of advantages, disadvantages, and future directions for electrochemical sensing of cannabinoids. The literature shows the lowest limit of detection to be 3.3 pg of Δ⁹-THC/mL using electrochemical immunosensors, while electrodes fabricated with low cost methods such as screen-printing and carbon paste can detect as little as 25 and 1.26 ng of Δ⁹-THC/mL, respectively. Future research will include nanomaterial modified working electrodes, for simultaneous sensing of multiple cannabinoids. Additionally, there should be an emphasis on selectivity for cannabinoids in the presence of interfering compounds. Sensors should be fully integrated on biocompatible substrates with control electronics and intelligent components for wearable diagnostics. We hope this Review will prove to be the seminal work in the electrochemical sensing of cannabinoids.

Simultaneous detection of salivary Δ9-tetrahydrocannabinol and alcohol using a Wearable Electrochemical Ring Sensor

Driving under the influence of cannabis and alcohol represents a major safety concern due to the synergistic or additive effect of these substances of abuse. Hence, rapid road-site testing of these substances is highly desired to reduce risks of fatal accidents. Here we describe a wearable electrochemical sensing device for the simultaneous direct, decentralized, detection of salivary THC and alcohol. The new ring-based sensing platform contains a voltammetric THC sensor and an amperometric alcohol biosensor on the ring cap, along with the wireless electronics embedded within the ring case. Rapid replacement of the disposable sensing-electrode ring cap following each saliva assay is accomplished by aligning spring-loaded pins, mounted on the electronic board (PCB), with the current collectors of the sensing electrodes. The printed dual-analyte sensor ring cover is based on a MWCNT/carbon electrode for the THC detection along with a Prussian-blue transducer, coated with alcohol oxidase/chitosan reagent layer, for the biosensing of alcohol. THC and alcohol can thus be detected simultaneously in the same diluted saliva sample within 3 min, with no cross talk and no interferences from the saliva matrix. The new wearable ring sensor platform should enable law enforcement personnel to screen drivers in a single traffic stop and offers considerable promise for addressing growing concerns of drug-impaired driving.