Investigation of fraud in the production of butter: a forensic case study of criminal association.

Butter is among the most popular and commercially valuable dairy products. Its high commercial value makes it a major target for adulteration, which aims to reduce production costs by using lower-quality fats and oils from other sources. The annual global market is around USD 30 billion (2023), expected to reach USD 36 billion in 2028, which also justifies the enormous interest in adulteration. In this work, a confirmed case of butter adulteration was studied by Nuclear Magnetic Resonance (NMR) and Stable Carbon Isotopic Ratio Analysis (SCIRA) techniques, employed to detect the inclusion in butter production of vegetable oils, such as soybean and palm oils. A total of 21 samples seized by the Brazilian Federal Police were analysed by NMR and SCIR, and compared to original butter obtained from commercial sources. The composition of all the seized samples was a mixture of butter (dairy fat of animal origin) with fat of vegetable origin (soybean and palm oil) and did not contain milk as a major component. While NMR was an unequivocal choice to discriminate the chemical composition of food samples, identifying the short-chain saturated fatty acids present in milk fat, including the butyryl alkyl chain, SCIRA was able to discriminate the origin of fat present in the butter samples as C3 sources, such as palm vegetable oils.

Applying multivariate techniques to fingerprint water quality impact of the Fundão Dam breach within the Rio Doce basin.

The Fundão Dam breach on 5 November 2015 (the "Event") released tailings, water, soil and/or sediments, and other debris to downstream watercourses. This breach included both direct and indirect impacts from scouring of soils and sediments along and within the affected courses. Multivariate statistical techniques were used to determine the potential of fingerprinting the impact of the breach compared to pre-Event water quality conditions and unaffected watercourses. The selection of key parameters is an important first step for multivariate analyses. Analysis of too many parameters can mask important trends and relationships, while analysis of too few may miss significant water quality indicators. A two-phased selection process was used to identify key parameters that indicated impact from the Event: (a) unbiased, principal component analysis to extract chemically dominant profiles among all measured parameters and (b) comparison of metals' concentrations between unaffected soils and/or sediments and tailings samples. Radar charts of key parameters along with statistical comparisons to pre-Event and not-affected waterways were then aggregated over space and time to assess impact and potential recovery to pre-Event conditions. Nine parameters were identified that characterize tailings-related (direct) and background soil and/or sediment-related (indirect) impacts. Spatially and temporally aggregated radar charts and nonparametric Mann-Whitney U tests were used to assess the statistical significance of these impacts during each wet season since the breach. Indirect parameters, like aluminum and lead, returned to pre-Event levels in the first wet season after the Event. By the 2018/2019 wet season, most of the direct and indirect parameters had returned to pre-Event levels. Integr Environ Assess Manag 2024;20:133-147. © 2023 NewFields Companies, LLC. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Laser-scribing fabrication of a disposable electrochemical device for forensic detection of crime facilitating drugs in beverage samples.

A portable and disposable laser-scribed graphene (LSG) device was fabricated on polyetherimide (PEI) substrate for electrochemical detection of benzodiazepines (BZ) drugs such as diazepam (DZ) and midazolam (MZ) in commercial beverage samples. Morphological characterizations of the LSG material recorded by scanning electron microscopy (SEM) revealed the porous nature of the proposed electrochemical device, which contributed to the enhancement of the electroactive area. Besides, the structural and electrochemical characterizations performed by Raman spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) measurements revealed that the PEI-LSG material presents highly disordered graphene-like structures and high electron transfer features, respectively. The electrochemical detection of DZ and MZ was carried out by Square Wave Voltammetry (SWV), whose analytical curves exhibited two linear intervals in concentrations ranging from 2.5 µmol L-1 to 25.0 µmol L-1 and from 25.0 µmol L-1 to 100.0 µmol L-1 for both BZ. We obtained limits of detection (LOD) and quantification (LOQ) of 0.66 and 2.18 µmol L-1 for DZ and 0.61 µmol L-1 and 2.01 µmol L-1 for MZ, respectively. The developed sensor was applied to detect DZ and MZ in commercial beverages such as juice, whisky, and sugarcane spirit samples to mimic potential forensic evidence of drug-facilitated crimes. The recoveries ranged from 97.1% to 117.2% for DZ and from 92.2% to 114.3% for MZ. In addition, the proposed method presented high manufacturing reproducibility (relative standard deviation (RSD) = 2.18% for DZ and RSD = 3.82% for MZ, n = 8 sensors) and adequate selectivity, highlighting the potential of PEI-LSG sensor as an excellent alternative method for forensic detection of crime facilitating drugs in commercial beverage samples.

The role of microorganisms in the biotransformation of psychoactive substances and its forensic relevance: a critical interdisciplinary review.

Microorganisms are widespread on the planet being able to adapt, persist, and grow in diverse environments, either rich in nutrient sources or under harsh conditions. The comprehension of the interaction between microorganisms and drugs is relevant for forensic toxicology and forensic chemistry, elucidating potential pathways of microbial metabolism and their implications. Considering the described scenario, this paper aims to provide a comprehensive and critical review of the state of the art of interactions amongst microorganisms and common drugs of abuse. Additionally, other drugs of forensic interest are briefly discussed. This paper outlines the importance of this area of investigation, covering the intersections between forensic microbiology, forensic chemistry, and forensic toxicology applied to drugs of abuse, and it also highlights research potentialities. Key points: Microorganisms are widespread on the planet and grow in a myriad of environments.Microorganisms can often be found in matrices of forensic interest.Drugs can be metabolized or produced (e.g. ethanol) by microorganisms.

Advances in cocaine signature methodology: Alkaloid and isotope profiles of coca grown in Puno, Peru.

Drug Enforcement Administration's (DEA) Cocaine Signature Program previously identified 19 coca-growing regions within South America and developed methodology to geo-source cocaine using a combination of trace cocaine alkaloids, stable isotopes, and multivariate statistics. Twenty-nine coca leaf samples collected in 2016 and 2019 from a previously unanalyzed coca-growing region located in Puno, Peru, were analyzed with this methodology. Trace cocaine alkaloids and stable isotopes were compared with other Peruvian regions. Minor differences were observed in the extracted cocaine alkaloid profiles when compared with samples collected from the Ucayali-Huallaga Valley and Cusco-Apurimac regions while the stable isotopes of δ2 H (-177.1‰) and δ18 O (23.8‰) were enriched. Puno's alkaloid and stable isotope results are presented in this publication to assist forensic laboratories and enhance their cocaine geo-sourcing capabilities.

Development of a simple and rapid screening method for the detection of 1-(3-chlorophenyl)piperazine in forensic samples.

1-(3-chlorophenyl) piperazine (mCPP) is a synthetic drug with hallucinogenic effects that has often been found in seized samples. In this context, easy to use point-of-care tests can be of great value in preliminary forensic analysis. Herein, we proposed a simple, fast, and portable electrochemical method for the detection of mCPP in seized samples. The method is based on the use of disposable screen-printed carbon electrodes (SPCE) and rapid screening procedures by square-wave voltammetry using minimal sample sizes (100 µL). mCPP showed an irreversible electrochemical oxidation process at +0.65 V on SPCE (vs Ag) using 0.04 mol L-1 Britton Robinson (BR) buffer solution (pH 7) as the supporting electrolyte. The proposed method exhibited a linear correlation (r = 0.998) between peak current and mCPP concentration in the range of 1-30 µmol L-1 (LOD = 0.1 µmol L-1). Interference studies were performed for adulterants and other classes of drugs of abuse, which can also be found in seized samples containing mCPP, such as caffeine, amphetamine, methamphetamine, 1-benzylpiperazine, 3,4-methylenedioxymethamphetamine, methylone, mephedrone, ethylone and 3, 4-methylenedioxypyrovalerone. The developed method presents great potential as a rapid and simple screening tool to detect mCPP in forensic samples.

Preliminary efficiency evaluation of development methods applied to aged sebaceous latent fingermarks.

Latent fingermarks are important trace evidence found in crime scenes mainly used for identification purposes. Once deposited, the composition of samples changes over time influencing the efficacy of latent fingermark development methods. In this sense, the aims of this work were to characterize the fatty acid (FA) profile of sebaceous latent fingermarks by GC-FID and to preliminarily evaluate the development efficiency of enhancement methods (powder dusting, iodine fuming and silver nitrate method) in a 30-day period of aging under controlled parameters of temperature, photoperiod and humidity. Results showed that myristic (7.51 ± 0.76% - 13.39 ± 1.26%), palmitic (35.91 ± 1.07% - 40.81 ± 2.52%), stearic (6.67 ± 0.36% - 9.13 ± 0.36%) and oleic (18.08 ± 0.25% - 20.93 ± 0.26%) acid varied significantly (p < 0.05) over the 30-day period of analysis. Regarding development efficiency, fluorescent orange powder and the silver nitrate method also increased their efficacy to develop latent fingermarks over time while the iodine fuming method decreased its efficiency. Silver black powder had constant efficacy in the tested period. Changes in the constitution of sebaceous marks possibly influenced the development efficiency of enhancement techniques. This knowledge is important to better understand the kinetic of aging and its influence on the development method.

Sandpaper-based electrochemical devices assembled on a reusable 3D-printed holder to detect date rape drug in beverages.

This study describes the development of a new electrochemical paper-based analytical device (ePAD) on alumina sandpaper substrate through a pencil-drawing process for square wave voltammetry measurements of midazolam maleate used as a "date rape drug" in beverages. The proposed ePAD was assembled on a reusable 3D printed holder to delimit its geometric area and ensure better robustness. The ePAD was characterized by scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and Raman spectroscopy. The direct drawing of ePADs on sandpaper platforms through a graphite pencil has offered suitable repeatability (RSD = 1.0%) and reproducibility (RSD = 4.0%) using [Fe(CN)6]4- as redox probe. The proposed ePAD provided linear behaviour in the midazolam maleate concentration range between 2.5 and 150 mg L-1 and a limit of detection of 2.0 mg L-1. The feasibility of the ePAD for forensic application was successfully demonstrated through the detection of midazolam in different beverages (water, beer, liquor, and vodka). The intended application revealed low interference of other compounds present in beverages. Based on the achieved results, the proposed ePAD has offered great accuracy with no statistical difference at 95% confidence level from the data recorded by high performance liquid chromatography. The operational simplicity and the robustness ensured by the assembling on a reusable 3D printed holder make the ePAD drawn on sandpaper platform a powerful and promising analytical tool for the analysis of "date rape drugs" opening new possibilities for on-site forensic investigations.

Development of a Pencil Drawn Paper-based Analytical Device to Detect Lysergic Acid Diethylamide (LSD)*, †.

The need for agile and proper identification of drugs of abuse has encouraged the scientific community to improve and to develop new methodologies. The drug lysergic acid diethylamide (LSD) is still widely used due to its hallucinogenic effects. The use of voltammetric methods to analyze narcotics has increased in recent years, and the possibility of miniaturizing the electrochemical equipment allows these methods to be applied outside the laboratory; for example, in crime scenes. In addition to portability, the search for affordable and sustainable materials for use in electroanalytical research has grown in recent decades. In this context, employing paper substrate, graphite pencil, and silver paint to construct paper-based electrodes is a great alternative. Here, a paper-based device comprising three electrodes was drawn on 300 g/m2 watercolor paper with 8B pencils, and its efficiency was compared to the efficiency of a commercially available screen-printed carbon electrode. Square wave voltammetry was used for LSD analysis in aqueous medium containing 0.05 mol/L LiClO4 . The limits of detection and quantification were 0.38 and 1.27 µmol/L, respectively. Both electrodes exhibited a similar voltammetric response, which was also confirmed during analysis of a seized LSD sample, with recovery of less than 10%. The seized samples were previously analyzed by GCMS technique, employing the full scan spectra against the software spectral library. The electrode selectivity was also tested against 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine. It was possible to differentiate these compounds from LSD, indicating that the developed paper-based device has potential application in forensic chemistry analyses.

High-throughput screening of cocaine, adulterants, and diluents in seized samples using capillary electrophoresis with capacitively coupled contactless conductivity detection.

Cocaine is one of the most frequently used illicit drug in the world. Therefore, the development of simple and fast methods for the detection of cocaine and common adulterants, diluents and impurities are extremely important in forensic investigations. The present study describes, for the first time, a method based on capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) for the rapid (2.5 min) and simultaneous quantification of cocaine, levamisole, lidocaine, carbonate, borate, chloride, nitrate, nitrite and sulphate. In the experiment, anions were separated in co-electroosmotic mode and cations in counter-electroosmotic mode employing a buffer solution composed by 10.0 mmol L-1 TAPS, 12 mmol L-1 NaOH and 0.2 mmol L-1 CTAB as the background electrolyte (pH = 8.8). The developed CE method demonstrated some interesting analytical characteristics such as: (i) a simple sample pretreatment step (only dilution in water and filtering), (ii) high-throughput screening (24 injections h-1), (iii) proper recovery values (between 72 and 118%), and (iv) an inter-day precision of less than 7% for all analytes. The procedure was successfully applied in the analysis of seized cocaine samples collected by the Integrated Forensics Post (PPI) of the Minas Gerais Civil Police (Uberaba, Minas Gerais State, Brazil), during the year of 2018.

Determination of the alcoholic content in whiskeys using micellar electrokinetic chromatography on microchips.

This report describes the development of a methodology based on micellar electrokinetic chromatography for the separation of alcohols on chip-based systems aiming the determination of alcoholic content in whiskey samples. The separation conditions were optimized the best results were achieved using 50 mmolL-1 phosphate buffer containing 30 mmolL-1 sodium dodecyl sulfate. The alcoholic content was determined in 16 seized whiskey samples from 4 different brands as well as in the original samples. The methodology presented herein allowed the correct classification of 75% of the seized samples as adulterated and the data obtained did not statistically differ from those recorded by a reference technique. The proposed analytical approach emerges as a promising tool to provide a rapid screening of the beverages authenticity and it may be useful to be widely explored for the quality control.

Investigation of midazolam electro-oxidation on boron doped diamond electrode by voltammetric techniques and density functional theory calculations: Application in beverage samples.

Midazolam (MID) is a sedative drug which can be added in beverage samples as drug-facilitated-sexual assault (date rape drug). This type of drug has short half-life in biological fluids (not detectable) which often prevents the correlation between drug abuse and crime. In this work, we described a simple and low-cost method for fast screening and selective determination of MID in beverage samples (vodka, whiskey and red wine). For the first time, the electrochemical oxidation of MID was used for this purpose. The oxidation mechanism was studied using electrochemical techniques (cyclic and square-wave voltammetry) and computational simulations (density functional theory calculations). Differential-pulse voltammetry, boron-doped diamond electrode (BDDE), and Britton-Robinson (BR) buffer (pH = 2) were selected as electrochemical analysis technique, working electrode and supporting electrolyte, respectively. Different linear response ranges (4-25 µmol L-1 with r = 0.9972; 1-10 µmol L-1 with r = 0.9951; 1-15 µmol L-1 with r = 0.9982) and limits of detection (0.46, 0.43 and 0.33 µmol L-1) were obtained for the analysis of vodka, whisky, and red wine solutions, respectively. The precision and accuracy were satisfactory considering the low relative standard deviation values (RSD < 6.3%, n = 15) and minimal sample matrix effects (recovery values between 87 and 103%).

4F-MDMB-BINACA: A New Synthetic Cannabinoid Widely Implicated in Forensic Casework.

This is the first report regarding the characterization of the new synthetic cannabinoid 4F-MDMB-BINACA. 4F-MDMB-BINACA was first analytically confirmed in seized drug material using gas chromatography-mass spectrometry (GC-MS), liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF), and nuclear magnetic resonance (NMR) spectroscopy. Subsequent to this characterization, 4F-MDMB-BINACA was detected in biological specimens collected as part of forensically relevant casework, including medicolegal death investigations and drug impaired driving investigations, from a variety of regions in the United States. Further analysis of biological specimens resulted in the identification of the metabolites 4F-MDMB-BINACA 3,3-dimethylbutanoic acid and 4-OH-MDMB-BINACA. 4F-MDMB-BINACA is appearing with increasing frequency as a contributory factor in deaths, creating morbidity and mortality risks for drug users. Laboratories must be aware of its presence and impact, incorporating 4F-MDMB-BINACA into workflows for detection and confirmation.

Forensic botany and forensic chemistry working together: application of plant DNA barcoding as a complement to forensic chemistry-a case study in Brazil.

Recently, Brazilian Federal Police used forensic chemistry and forensic botany techniques on a case. Two packets containing fragmented plant matter were seized and sent for forensic analysis. Forensic chemistry, the gold standard for evaluating plant material suspected to contain illicit substances, did not find illicit materials. Gas chromatography coupled mass spectrometry (GC-MS) identified thujone in the botanical material. Thujone is a chemical compound naturally found in many plant species, notably Artemisia absinthium. Because doubt remained, we next used plant DNA barcoding methods. Total DNA from plant tissue fragments was extracted and five different DNA regions were amplified, sequenced, and analyzed using plant DNA barcoding methods. Genetic analysis yielded 30 good quality sequences representing five taxa. Most specimens were identified as A. absinthium. Few studies focus on practical forensic applications of plant DNA barcoding methods using a case solved in a forensic laboratory with its difficulties and limitations. To the best of our knowledge, this is the first study to report an effective joint effort of forensic chemistry and botany techniques to assess plant material in Brazil. The availability of a new technical approach for the genetic sequencing of plant species will enhance many forensic investigations and inspire similar initiatives.

Redox titration on foldable paper-based analytical devices for the visual determination of alcohol content in whiskey samples.

This report describes the development of foldable paper-based analytical devices (PADs) to perform redox titrations. Paper devices were designed to contain three spot tests, which were wax printed and folded to create a three-layer structured platform and to promote the sample transport based on vertical flow. The proposed devices were explored for the visual determination of the alcoholic content in whiskey samples. For this purpose, a classical permanganometry reaction was employed to allow the indirect determination of ethanol based on the required amount of oxalic acid to react with the excess of permanganate in acidic medium. The endpoint of the redox titrations performed in different alcoholic concentrations was measured and revealed a good linear behavior for the ethanol concentration range between 0% and 50% (R2 = 0.992), achieving a limit of detection equal to 2.1%. The alcoholic content was determined in a total of 44 whiskey samples seized by the Brazilian Federal Police. When compared to genuine samples and using an established cut-off limit, 73% of the seized samples were correctly classified as whiskeys containing adulterated alcoholic content. The proposed method was compared to a reference protocol and no difference was observed at the confidence level of 95%. The instrumental simplicity, the low cost, the sample volume requirement, the short analysis time and mainly the inherent portability make these devices quite attractive for on-site forensic applications.

Rapid separation of post-blast explosive residues on glass electrophoresis microchips.

This study describes the development of an analytical methodology based on the use of microchip electrophoresis (ME) devices integrated with capacitively coupled contactless conductivity detection (C4 D) for the separation and detection of inorganic anions in post-blast explosive residues. The best separation condition was achieved using a running buffer composed of 35 mmol/L lactic acid, 10 mmol/L histidine and 0.070 mmol/L cetyl(trimethyl ammonium) bromide. For C4 D measurements, the highest sensitivity was obtained applying a 700 kHz sinusoidal wave with excitation voltage of 20 Vpp . The separation of Cl- , NO3- , NO2- , SO42- , ClO4- and ClO3- was performed within ca. 150 s with baseline resolution and efficiencies between 4.4 × 104 and 1.7 × 105 plates/m. The found limits of detection ranged between 2.5 and 9.5 µmol/L. Last, real samples of post-blast explosive residues were analyzed on the ME-C4 D devices obtaining successfully the determination of Cl- , NO3- and SO42- . The achieved concentration values varied between 12.8-72.5 mg/L for Cl- , 1.7-293.1 mg/L for NO3- and 1.3-201.3 mg/L for SO42- . The data obtained using ME-C4 D devices were in good agreement with the concentrations found by ion chromatography. The approach reported herein has provided short analysis time, instrumental simplicity, good analytical performance and low cost. Furthermore, the ME-C4 D devices emerge as a powerful and portable analytical platform for on-site analysis demonstrating to be a promising tool for the crime scene investigation.

Screening of seized cocaine samples using electrophoresis microchips with integrated contactless conductivity detection.

This study describes the development of a new analytical method for the separation and detection of cocaine (COC) and its adulterants, or cutting agents, using microchip electrophoresis (ME) devices coupled with capacitively coupled contactless conductivity detection (C4 D). All the experiments were carried out using a glass commercial ME device containing two pairs of integrated sensing electrodes. The running buffer composed of 20 mmol/L amino-2-(hydroxymethyl) propane-1,3-diol and 10 mmol/L 3,4-dimethoxycinnamic acid provided the best separation conditions for COC and its adulterants with baseline resolution (R > 1.6), separation efficiencies ranging from (2.9 ± 0.1) to (3.2 ± 0.2) × 105 plates/m, and estimated LOD values between 40 and 150 µmol/L. The quantification of COC was successfully performed in four samples seized by the Brazilian Federal Police Department and all predicted values agree with values estimated by the reference method. Some other interfering species were detected in the seized samples during the screening procedure on ME-C4 D devices. While lidocaine was detected in sample 3, the presence of levamisole was observed in samples 2 and 4. However, their concentrations were estimated to be below the LOQ. ME-C4 D devices have proved to be quite efficient for the identification and quantification of COC with errors lower than 10% when compared to the data obtained by a reference method. The approach herein reported offers great potential to be used for on-site COC screening in seized samples.

EASI-IMS an expedite and secure technique to screen for 25I-NBOH in blotter papers.

The increasing number of new psychoactive substances (NPS) and their quick worldwide spreading, often only slightly modified in the form of new derivatives and analogues, have brought the need for fast, wide-ranging, and unequivocal identification methods in clinical and forensic investigations. Because it usually provides secure results, gas chromatography coupled to mass spectrometry (GC-MS) has been routinely employed as the standard technique for the detection of NPS in blotter papers. For 25I-NBOH (N-(2-hydroxybenzyl)-2-(4-iodo-2,5-dimethoxyphenyl)ethan-1-aminium), however, GC-MS analysis of an blotter paper extract leads to incorrect results. In this work, we investigated whether easy ambient sonic-spray mass spectrometry imaging (EASI-IMS), and ambient ionization MS method can be applied directly to the surface of the sample requiring therefore no extraction or sample preparations, would serve as an efficient, sensitive, and secure alternative for 25I-NBOH screening.

Paper-based microfluidic devices on the crime scene: A simple tool for rapid estimation of post-mortem interval using vitreous humour.

This paper describes for the first time the use of paper-based analytical devices at crime scenes to estimate the post-mortem interval (PMI), based on the colorimetric determination of Fe2+ in vitreous humour (VH) samples. Experimental parameters such as the paper substrate, the microzone diameter, the sample volume and the 1,10-phenanthroline (o-phen) concentration were optimised in order to ensure the best analytical performance. Grade 1 CHR paper, microzone with diameter of 5 mm, a sample volume of 4 µL and an o-phen concentration of 0.05 mol/L were chosen as the optimum experimental conditions. A good linear response was observed for a concentration range of Fe2+ between 2 and 10 mg/L and the calculated values for the limit of detection (LOD) and limit of quantification (LOQ) were 0.3 and 0.9 mg/L, respectively. The specificity of the Fe2+ colorimetric response was tested in the presence of the main interfering agents and no significant differences were found. After selecting the ideal experimental conditions, four HV samples were investigated on paper-based devices. The concentration levels of Fe2+ achieved for samples #1, #2, #3 and #4 were 0.5 ± 0.1, 0.7 ± 0.1, 1.2 ± 0.1 and 15.1 ± 0.1 mg/L, respectively. These values are in good agreement with those calculated by ICP-MS. It important to note that the concentration levels measured using both techniques are proportional to the PMI. The limitation of the proposed analytical device is that it is restricted to a PMI greater than 1 day. The capability of providing an immediate answer about the PMI on the crime scene without any sophisticated instrumentation is a great achievement in modern instrumentation for forensic chemistry. The strategy proposed in this study could be helpful in many criminal investigations.

The Application of Voltammetric Analysis of Δ(9) -THC for the Reduction of False Positive Results in the Analysis of Suspected Marijuana Plant Matter.

The development of methodologies using inexpensive, fast, and reliable instrumention is desirable in illicit drug analysis. The purpose of this study was based on cyclic voltammetry technique to differentiate the electrochemical behavior of ∆(9) -THC, the psychoactive substance in marijuana, and five different extract plants to yield false positive results after analysis protocol for cannabinoids using thin-layer chromatography and Fast Blue B salt. After applying a deposition potential of -0.5 V in a glassy carbon working electrode, the results indicated an anodic peak current at 0.0 V versus Ag/AgCl after addition of ∆(9) -THC solution in the electrochemical cell, and limits of detection and quantification were 1.0 ng mL(-1) and 3.5 ng mL(-1) , respectively. Other interfering plants showed distinct amperometric responses. This methodology was useful to detect ∆(9) -THC even in the presence of the Fast Blue B salt, which avoided false positive results for all the studied extract plants.