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

Illicit drugs in Brazil: environmental consequences and consumption patterns

This article reviews the literature on the consumption, street drug analysis, distribution, and main environmental impacts of illicit drugs in Brazil and analyzes the III National Survey on Drug Use by the Brazilian Population. The literature review is based on articles published in national and international journals between 2018 and 2023. This review consists of two analyses, the first of which addresses publications from the last 6 years on the monitoring of illicit drugs in Brazil and a second analysis based on the III National Survey on Drug Use that addresses the different possibilities of contact with drugs. The results revealed that the Southeast region of Brazil has the highest number of studies on the subject, especially in the state of São Paulo, while the North and Northeast regions have the lowest number of studies. The Midwest regions only have studies in the federal capital city, Brasília, while no studies were found in states bordering countries that produce illicit drugs, such as Paraguay and Bolivia. Analytical methods that use the concept of miniaturization, green chemistry, and the adoption of acceptance methods are frequent in most articles. Chemometric and statistical tools are widely used for the analysis, development, and conclusion of identification and quantification methods. Among the articles studied, there was a predominance in the analysis of cocaine metabolites and cannabis metabolites in the aquatic environment, where their concentrations ranged from 0.01 to 2000 ng L-1. Studies also reported bioaccumulation in marine biota with concentrations of up to 4.58 µg kg-1 for mussels and sediments, posing a risk to algae, crustaceans, and fish. Furthermore, the data show that the consumption of illicit drugs is increasing in Brazil, especially among young people.

Irgafos 168 and Irganox 1076 as new cocaine cutting agents: A COVID-19 pandemic impact on cocaine profiling and trafficking in Brazil

BACKGROUNDS

Restrictions in movement and closure of borders imposed by the Sars-Cov- 2 worldwide pandemic have affected the global illicit drug market, including cocaine trafficking. In this scenario, comparing cutting agents added to the cocaine and the drug purity are valuable strategies to understand how the drug trade has been impacted by the pandemic.

METHODS

In this work, 204 cocaine salt materials seized in the Brazilian Federal District, before (2019) and during COVID-19 pandemics (2020) were analyzed by two analytical techniques: gas chromatography-mass spectrometry (GC-MS) and Fourier-transform infrared spectroscopy (FTIR). Statistical analyses, including Principal Component Analysis (PCA), were applied to evaluate the COVID-19 pandemic impact in the local market. Bibliometric analysis was performed as a forensic intelligence tool.

RESULTS

From 2019-2020, cocaine average purity decreased 26 % while the frequency of cutting agents, as caffeine and anesthetics (lidocaine, tetracaine) increased. The high percentage of unknown were increased. Different cocaine profiling seized in 2020 showed new cutting agents, such as Irganox 1076, and Irgafos 168, indicating a trend on new adulterants/diluents introduced in the local market to mitigate the local drug shortage. Also in 2020, there was an increase in the local cocaine seizures, despite of the cocaine drug purity decreased by 26 % compared to 2019.

CONCLUSIONS

Taken together, these data showed that the covid-19 pandemics has impacted cocaine trafficking in the Brazilian Federal District, an increase in cocaine seizures, which may indicate greater demand for the drug and, specially, changes in the cocaine purity and cutting agents profiling showing how traffickers tried to minimize difficulties in crossing the Brazilian border during COVID-19 restrictions. The information is relevant since Brazil is one of the major departure points for traded cocaine to the world. Bibliometric analysis showed that Irgafos 168 and Irganox 1076 were consistently identified as cocaine cutting agents for the first time.

Molecular Insights and Clinical Outcomes of Drugs of Abuse Adulteration: New Trends and New Psychoactive Substances

Adulteration is a well-known practice of drug manufacturers at different stages of drug production. The intentional addition of active ingredients to adulterate the primary drug may enhance or mask pharmacological effects or may produce more potent drugs to increase the number of available doses and the dealer's profit. Adulterants found in different drugs change over time in response to different factors. A systematic literature search in PubMed and Scopus databases and official international organizations' websites according to PRISMA guidelines was performed. A total of 724 studies were initially screened, with 145 articles from PubMed and 462 from Scopus excluded according to the criteria described in the Method Section. The remaining 117 records were further assessed for eligibility to exclude articles without sufficient data. Finally, 79 studies were classified as "non-biological" (n = 35) or "biological" (n = 35 case reports; n = 9 case series) according to the samples investigated. Although the seized samples analyses revealed the presence of well-established adulterants such as levamisole for cocaine or paracetamol/acetaminophen for heroin, the reported data disclosed new adulteration practices, such as the use of NPS as cutting agents for classic drugs of abuse and other NPS. For example, heroin adulterated with synthetic cannabinoids or cocaine adulterated with fentanyl/fentalogues raised particular concern. Notably, adulterants play a role in some adverse effects commonly associated with the primary drug, such as levamisole-adulterated cocaine that may induce vasculitis via an autoimmune process. It is essential to constantly monitor adulterants due to their changing availability that may threaten drug consumers' health.

In-line sample concentration in capillary electrophoresis by cyclodextrin to admicelle microextraction

Cyclodextrins (CDs) as a pseudophase in pseudophase-to-pseudophase microextraction (P2ME) in capillary zone electrophoresis (CZE) are proposed. In this P2ME mode called CD to admicelle ME, a long plug of dilute analyte solution prepared in cetyltrimethylammonium bromide (CTAB) at the critical micellar concentration was injected into the capillary. This formed CTAB admicelles at the interface between the solution and the negatively charged capillary surface, where the analytes were trapped. The injection of CD solution released the admicelles and the analytes from the capillary surface due to the formation of stable CD/CTAB inclusion complexes. The analytes are concentrated at the CD front during injection and voltage separation. Various neutral CDs were found to be effective for CD to admicelle ME. To implement this in-line sample concentration technique in CZE, CD concentration, sample injection time, and sample:CD solution injection ratio were optimized. The optimized conditions for five model anionic analytes, namely, 4-bromophenol, sulindac, sulfamethizole, 4-vinylbenzoic acid, and succinylsulfathiazole, were 20 mM α-CD in 20 mM sodium tetraborate (pH 9.2) solution, sample injection time of 370 s, and CD:sample injection ratio of 1:2. The sensitivity enhancement factors (SEFs) were between 112 and 168. The SEFs of sulindac and sulfamethizole in particular were similar to previously published off-line microextraction techniques, which are typically time-consuming. The calculated values of LOQ, intra-/inter-day (n = 6/n = 10, 3 days) repeatability, and linearity (R2) of CD to admicelle ME were 0.0125-0.05 µg/mL, 1.5-4.6%, 1.8-4.8%, and ≥0.999, respectively. Finally, the potential of CD to admicelle ME to the analysis of artificial urine samples was demonstrated.

Cocaine in Different Matrices: Recent Updates on Pretreatment and Detection Techniques

Cocaine abuse has attracted increased attention in the recent past since it can cause addiction and great harm to the normal human body. Due to cocaine exists in various complex matrices, the detection of it in different matrices is helpful to prevent abuse. It is thus imperative to establish efficient and accurate methods for pretreatment and detection of cocaine in different samples. The present study provides a summary of the research progress of cocaine pretreatment methods (such as different microextraction methods, QuEChERS, and solid phase extraction based on novel extraction materials) and detection approaches (such as liquid chromatography coupled with different detectors, gas chromatography and related techniques, capillary electrophoresis and sensors). A comparison of the pros and cons of different pretreatment and detection methods is presented. The findings of this study will provide a reference for selection of the most suitable cocaine pretreatment and detection techniques.

A highly sensitive electrochemical aptasensor for cocaine detection based on CRISPR-Cas12a and terminal deoxynucleotidyl transferase as signal amplifiers

Cocaine is one of the mainly used illegal drugs in the world. Using the signal amplification elements of terminal deoxynucleotidyl transferase (TdT) and CRISPR-Cas12a, a highly sensitive and simple electrochemical aptasensor was introduced for cocaine quantification. When, no cocaine existed in the sample, the 3'-end of complementary strand of aptamer (CS) was extended by TdT, leading to the activation of CRISPR-Cas12a and remaining of very short oligonucleotides on the working electrode. So, the current signal was remarkably promoted. With the presence of cocaine, CS left the electrode surface. Thus, nothing changed following the incubation of TdT and CRISPR-Cas12a and the Aptamer/Cocaine complex presented on the electrode. Consequently, the [Fe(CN)₆]^3-/4- could not freely reach the electrode surface and the signal response was weak. Under optimal situations, the biosensor revealed a wide linear relation from 40 pM to 150 nM with detection limit of 15 pM for cocaine. The sensitivity of the analytical system was comparable and even better than other reported methods for cocaine detection. The designed method displayed excellent cocaine selectivity. The aptasensor could work well for cocaine assay in serum samples. So, the aptasensor is expected to be an efficient analytical method with broad applications in the determination of diverse analytes.

A facile online multi-gear capacitively coupled contactless conductivity detector for an automatic and wide range monitoring of high salt in HPLC

Sensing the electrolyte solution or aqueous–organic mixture has attracted much interest in chemical separation, pharmaceutical engineering, bioprocess, and biochemical experiments.

Fast Quantitative LC-MS/MS Determination of Illicit Substances in Solid and Liquid Unknown Seized Samples

Narcotic and psychotropic substances are natural, synthetic, or semisynthetic compounds that are present in both solid and liquid illicit products. The alterations effects on the central nervous system related to their use can be psycholeptic, psychoanaleptic, or psychodiseptic and are able to generate tolerance, addiction, or dependence phenomena, creating social and public order problems. In this scenario, the analytical evaluations that aim to determine these analytes in seized nonbiological samples, and which assume the character of judicial evidence, must meet high analytical requirements of reliability, transparency, and procedures uniformity at a national level. For the first time in the literature, the herein validated method is able to provide the simultaneous quantitative determination of 37 of the most common narcotic substances as well as the most commonly used excipients/adulterants found in seized illicit material. Additionally, the validated method can process both solid and liquid samples maintaining the precision and trueness levels (intraday and interday) in accordance with the U.S. Food and Drug Administration and European Medicines Agency international guidelines (<14.31 and <13.41%, respectively). Furthermore, it provides a simple and fast procedure for sample preparation using the dilute and shoot approach, exploiting the sensitivity and selectivity of the LC-MS/MS instrument configuration used and the signal acquisition in multiple reaction monitoring (MRM) mode (both positive and negative polarization modes).

Potentiality of miniaturized techniques for the analysis of drugs of abuse

Capillary electromigration (CE) and liquid chromatographic techniques (CLC/nano-LC) are miniaturized techniques offering distinct advantages over conventional ones in the field of separation science. Among these, high efficiency, high chromatographic resolution, and use of minute volumes of both mobile phase and sample volumes are the most important. CE and CLC/nano-LC have been applied to the analysis of many compounds including peptides, proteins, drugs, enantiomers, ions, etc. Over the years, the methods described here have also been used for the analysis of compounds of clinical, forensic, and toxicological interest. In this review article, the main features of the mentioned techniques are summarized. Their potentiality for the analysis of drugs of abuse are discussed. Some selected applications in this field in the period of 2015-present are also reported.

Indirect calibration for capillary electrophoresis with conductivity detection

There is a growing interest in conductivity detection for capillary electrophoresis; especially because of capacitively coupled contactless conductivity approach. This robust and general-purpose detector has another lesser-known feature: sensitivity does not depend on the very chemical nature of the analyte, but only on its effective charge and effective mobility. Therefore, the calibration curve prepared for a given species may be used to quantify another one of same charge and mobility. In the absence of a species (calibrant) of exactly the same mobility, two or more calibrants can be used. Provided the sensitivity varies smoothly in the desired region of mobility, it can be mathematically described by a function. For small ranges of mobilities, a linear behavior is expected, and the sensitivity for the analyte can be obtained by interpolation. This technique was investigated for eight different combinations of mono- and double-charged cationic and anionic analytes using buffered and unbuffered background electrolytes (BGEs). For most of the applications, a linear model was enough to describe the sensitivity (0.988 < R² < 0.998), but for ample range of mobilities, the inclusion of a hyperbolic term was needed (0.995 < R² < 0.999). This technique has a great potential to be used in field applications and in laboratories when the analytes are unstable or they are not available to be used in the preparation of standard solutions.

3D-printing for forensic chemistry: voltammetric determination of cocaine on additively manufactured graphene-polylactic acid electrodes

Cocaine is probably one of the most trafficked illicit drugs in the world. For this reason, police forces require fast, selective, and sensitive methods for cocaine detection at crime scenes. Taking benefit of additive manufacturing, we demonstrate that 3D-printed graphene-polylactic acid (G-PLA) electrodes using the affordable fused deposition modelling technique can identify and quantify cocaine in seized drugs. The detection of cocaine based on its electrochemical oxidation on such electrodes was dramatically improved after an electrochemical surface treatment that generates reduced graphene oxide (anodic followed by a cathodic treatment). Square-wave voltammetric determination of cocaine was achieved in the concentration range between 20 and 100 μmol L-1, with a detection limit of 6 μmol L-1, and free from the interference of paracetamol, caffeine, phenacetin, lidocaine, benzocaine and levamisole, which are common adulterants found in seized drugs. The analytical characteristics obtained using 3D-printed G-PLA electrodes were comparable with those of previously reported electrochemical sensors, but presented the inherent advantages of the 3D-printing technology that enables low-cost, reproducible, and large-scale production of such electrodes in remote areas combined with the use of an environmentally-friendly biopolymer.

Fully inkjet-printed multilayered graphene-based flexible electrodes for repeatable electrochemical response

Graphene has proven to be useful in biosensing applications. However, one of the main hurdles with printed graphene-based electrodes is achieving repeatable electrochemical performance from one printed electrode to another. We have developed a consistent fabrication process to control the sheet resistance of inkjet-printed graphene electrodes, thereby accomplishing repeatable electrochemical performance. Herein, we investigated the electrochemical properties of multilayered graphene (MLG) electrodes fully inkjet-printed (IJP) on flexible Kapton substrates. The electrodes were fabricated by inkjet printing three materials – (1) a conductive silver ink for electrical contact, (2) an insulating dielectric ink, and (3) MLG ink as the sensing material. The selected materials and fabrication methods provided great control over the ink rheology and material deposition, which enabled stable and repeatable electrochemical response: bending tests revealed the electrochemical behavior of these sensors remained consistent over 1000 bend cycles. Due to the abundance of structural defects (e.g., edge defects) present in the exfoliated graphene platelets, cyclic voltammetry (CV) of the graphene electrodes showed good electron transfer (k = 1.125 × 10⁻² cm s⁻¹) with a detection limit (0.01 mM) for the ferric/ferrocyanide redox couple, [Fe(CN)₆]^−3/−4, which is comparable or superior to modified graphene or graphene oxide-based sensors. Additionally, the potentiometric response of the electrodes displayed good sensitivity over the pH range of 4–10. Moreover, a fully IJP three-electrode device (MLG, platinum, and Ag/AgCl) also showed quasi-reversibility compared to a single IJP MLG electrode device. These findings demonstrate significant promise for scalable fabrication of a flexible, low cost, and fully-IJP wearable sensor system needed for space, military, and commercial biosensing applications.

A fully inkjet printed and flexible multilayer graphene based three electrode device showed electrochemical reversibility.

Capacitively coupled contactless conductivity detection for analytical techniques - Developments from 2018 to 2020

The developments of analytical contactless conductivity measurements based on capacitive coupling over the two years from mid-2018 to mid-2020 are covered. This mostly concerns applications of the technique in zone electrophoresis employing conventional capillaries and to a lesser extent lab-on-chip devices. However, its use for the detection in several other flow-based analytical methods has also been reported. Detection of bubbles and measurements of flow rates in two-phase flows are also recurring themes. A few new applications in stagnant aqueous samples, e.g. endpoint detection in titrations and measurement on paper-based devices, have been reported. Some variations of the design of the measuring cells and their read-out electronics have also been described.