Determination of cocaine and its major metabolite benzoylecgonine in several matrices obtained from deceased individuals with presumed drug consumption prior to death

Post-mortem toxicological analysis of cocaine: main biological samples and analytical methods

This scoping review intends to identify the most used analytical methods and biological samples in the post-mortem forensic toxicological analysis of cocaine and its metabolites. A scoping review was performed based on the question "What are the analytical methods and types of biological samples most frequently used to identify and quantify cocaine in post-mortem forensic toxicology?" The studies were selected from five databases and, after exclusions, the data were tabulated, analyzed, and reported. Twenty-one articles published between 2012 and 2022 were filtered from five different databases to be studied. The collected data indicate that the most used biological samples were blood and hair. The most used sample preparation technique was solid phase extraction, while the most mentioned chromatography method was liquid chromatography with mass spectrometry. This review presents and discusses the state of the art regarding methods for the detection sensitivity spectrum, why limits of quantification are so important for these methods, and what are the most suitable biological samples to be utilized in each case. Cocaine and metabolites are important in forensic toxicologic post-mortem analysis. However, there is little concern in the development of miniaturized and automated sample preparation in this field. Besides, there is not enough understanding of post-mortem redistribution, tolerance, drug-drug interactions, and pre-existing medical conditions.

Development of an innovative analytical method for forensic detection of cocaine, antidepressants, and metabolites in postmortem blood using magnetic nanoparticles

Cocaine and antidepressants rank high globally in substance consumption, emphasizing their impact on public health. The determination of these compounds and related substances in biological samples is crucial for forensic toxicology. This study focused on developing an innovative analytical method for the determination of cocaine, antidepressants, and their related metabolites in postmortem blood samples, using unmodified commercial Fe3O4 nanoparticles as a sorbent for dispersive magnetic solid-phase extraction (m-d-SPE), coupled with liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis. An aliquot of 100 µL of whole blood and 5 µL of the internal standard pool were added to 30 mg of nanoparticles. The nanoparticles were separated from the sample using a neodymium magnet inserted into a 3D-printed microtube rack. The liquid was then discarded, followed by desorption with 300 µL of 1/1/1 acetonitrile/methanol/ethyl acetate. The sample was vortexed and separated, and 1.5 µL of the organic supernatant was injected into the LC-MS/MS. The method was acceptably validated and successfully applied to 263 postmortem blood samples. All samples evaluated in this study were positive for at least one substance. The most frequent analyte was benzoylecgonine, followed by cocaine and cocaethylene. The most common antidepressants encountered in the analyzed samples were citalopram and fluoxetine, followed by fluoxetine's metabolite norfluoxetine. This study describes the first report of this sorbent in postmortem blood analysis, demonstrating satisfactory results for linearity, precision, accuracy, and selectivity for all compounds. The method's applicability was confirmed, establishing it as an efficient and sustainable alternative to traditional techniques for forensic casework.

Evaluation of hemaPEN® sampling device for measurement of cocaine and metabolites in capillary blood by LC-MS/MS

Background: Dried blood spot sampling has been reported for on-site collection of specimens, but measurements are affected by blood hematocrit, and special handling is required, especially for forensic applications. The hemaPEN^® blood collection device was developed to produce spots with constant volume. Results: Linearity between 1 and 500 ng/ml was shown for cocaine and the metabolites benzoylecgonine and cocaethylene. The assay demonstrated acceptable precision and accuracy, and analytes were stable for 7 days when kept inside hemaPEN devices. Accuracy of the assay was affected by hematocrit but was within acceptable limits. Conclusion: Use of the hemaPEN, which retains dried blood within the device, could be advantageous for the quantification of illicit drugs in capillary blood compared with conventional dried blood spot collection.

Alternative matrices in forensic toxicology: a critical review

Purpose

The use of alternative matrices in toxicological analyses has been on the rise in clinical and forensic settings. Specimens alternative to blood and urine are useful in providing additional information regarding drug exposure and analytical benefits. The goal of this paper is to present a critical review on the most recent literature regarding the application of six common alternative matrices, i.e., oral fluid, hair, sweat, meconium, breast milk and vitreous humor in forensic toxicology.

Methods

The recent literature have been searched and reviewed for the characteristics, advantages and limitations of oral fluid, hair, sweat, meconium, breast milk and vitreous humor and its applications in the analysis of traditional drugs of abuse and novel psychoactive substances (NPS).

Results

This paper outlines the properties of six biological matrices that have been used in forensic analyses, as alternatives to whole blood and urine specimens. Each of this matrix has benefits in regards to sampling, extraction, detection window, typical drug levels and other aspects. However, theses matrices have also limitations such as limited incorporation of drugs (according to physical–chemical properties), impossibility to correlate the concentrations for effects, low levels of xenobiotics and ultimately the need for more sensitive analysis. For more traditional drugs of abuse (e.g., cocaine and amphetamines), there are already data available on the detection in alternative matrices. However, data on the determination of emerging drugs such as the NPS in alternative biological matrices are more limited.

Conclusions

Alternative biological fluids are important specimens in forensic toxicology. These matrices have been increasingly reported over the years, and this dynamic will probably continue in the future, especially considering their inherent advantages and the possibility to be used when blood or urine are unavailable. However, one should be aware that these matrices have limitations and particular properties, and the findings obtained from the analysis of these specimens may vary according to the type of matrix. As a potential perspective in forensic toxicology, the topic of alternative matrices will be continuously explored, especially emphasizing NPS.

Cerebrospinal fluid in forensic toxicology: Current status and future perspectives

In forensic toxicology, alternative biological materials are very useful and important, e.g. in the case of lack of basic body fluids. One alternative biological material is cerebrospinal fluid (CSF). The procedures of the collection of biological material during the autopsy are performed in accordance with local, usually national recommendations, which most often require updating. It is very difficult to assess the possibility of using CSF as an alternative biological material for toxicological studies for the presence of drugs, intoxicants, including new psychoactive substances (commonly known as designer drugs), psychotropic substances, and ethyl alcohol, based on current data. Previous research suggests that CSF may be useful in toxicological studies, but these aspects need to be investigated more carefully because studies have collected CSF from different sites and often the results of different authors are not comparable. It would be necessary to prepare guidelines, e.g. the site of CSF collection that may influence the results of quantitative analysis. It would also be necessary to replicate some studies with a different collection site or a more recent analytical technique, e.g. for comparative testing of blood ethanol and cerebrospinal fluid. Cerebrospinal fluid can be a valuable information carrier in the absence of classic biological material from an autopsy. Investigating these aspects in more detail could allow the future use of this alternative material for routine toxicology analyzes in a forensic laboratory.

Evaluation of Cocaine Effect on Endogenous Metabolites of HepG2 Cells Using Targeted Metabolomics

Cocaine toxicity has been a subject of study because cocaine is one of the most common and potent drugs of abuse. In the current study the effect of cocaine on human liver cancer cell line (HepG2) was assessed. Cocaine toxicity (IC50) on HepG2 cells was experimentally calculated using an XTT assay at 2.428 mM. The metabolic profile of HepG2 cells was further evaluated to investigate the cytotoxic activity of cocaine at 2 mM at three different time points. Cell medium and intracellular material samples were analyzed with a validated HILIC-MS/MS method for targeted metabolomics on an ACQUITY Amide column in gradient mode with detection on a triple quadrupole mass spectrometer in multiple reaction monitoring. About 106 hydrophilic metabolites from different metabolic pathways were monitored. Multivariate analysis clearly separated the studied groups (cocaine-treated and control samples) and revealed potential biomarkers in the extracellular and intracellular samples. A predominant effect of cocaine administration on alanine, aspartate, and glutamate metabolic pathway was observed. Moreover, taurine and hypotaurine metabolism were found to be affected in cocaine-treated cells. Targeted metabolomics managed to reveal metabolic changes upon cocaine administration, however deciphering the exact cocaine cytotoxic mechanism is still challenging.

Spectroscopy as a useful tool for the identification of changes with time in post-mortem vitreous humor for forensic toxicology purposes

Vitreous humor (VH) is an alternative biological matrix with a great advantage of longer availability for analysis due to the lack of many enzymes. The use of VH in forensic toxicology may have an added benefit, however, this application requires rapid, simple, non-destructive, and relatively portable analytical analysis methods. These requirements may be met by Fourier transform infrared spectroscopy technique (FT-IR) equipped with attenuated total reflection accessory (ATR). FT-IR spectra of vitreous humor samples, deposited on glass slides, were collected and subsequent chemometric data analysis by means of Hierarchical Cluster Analysis and Principal Component Analysis was conducted. Differences between animal and human VH samples and human VH samples stored for diverse periods of time were detected. A kinetic study of changes in the VH composition up to 2 weeks showed the distinction of FT-IR spectra collected on the 1st and 14th day of storage. In addition, data obtained for the most recent human vitreous humor samples—collected 3 and 2 years before the study, presented successful discrimination of all time points studied. The method introduced was unable to detect mephedrone addition to VH in the concentration of 10 µg/cm3.

Graphic abstract

Acidic Drug Concentrations in Postmortem Vitreous Humor and Peripheral Blood

Vitreous humor is a potential alternative matrix for postmortem toxicology drug screens when peripheral blood is unavailable. It is easily and reliably collected and may not suffer from the same postmortem redistribution as seen in blood. Here, we compared the concentrations of 7 acidic drugs (acetaminophen, ibuprofen, naproxen, salicylic acid, carbamazepine, phenobarbital and phenytoin) in peripheral blood and vitreous fluid collected in 89 autopsy cases. Analysis was done by high-performance liquid chromatography with diode-array detection. Overall, we found that vitreous drug concentrations were significantly lower than peripheral blood with median vitreous to peripheral blood (V/PB) ratios ranging from 0.0 to 0.6 (mean, 0.1-0.6). The correlations between the concentrations of over-the-counter analgesics in peripheral blood versus vitreous fluid were poor, with acetaminophen exhibiting the best linearity (R2 = 0.72). The antiepileptic drugs (carbamazepine, phenytoin and phenobarbital) exhibited good correlations between peripheral blood and vitreous humor, with all exhibiting an R2 ≥ 0.95. Overall, we have demonstrated the potential of vitreous fluid as an alternative matrix for the detection of select acidic drugs.

Study of the distribution of antidepressant drugs in vitreous humor using a validated GC/MS method

Vitreous humor has become in recent years an important alternative biological fluid in forensic toxicological analysis especially for the investigation of cases where alcohol and drugs of abuse are involved but there is limited scientific information regarding the distribution of antidepressant drugs in this material. This work aimed to study the distribution of antidepressant drugs in vitreous humor and to estimate the blood/vitreous humor concentration ratios of these drugs. For this purpose, a GC/MS method for the simultaneous determination of 9 antidepressant drugs, namely amitriptyline, nortriptyline, citalopram, clomipramine, fluoxetine, maprotiline, mirtazapine, sertraline and venlafaxine, and 4 of their metabolites, namely desmethylmaprotiline, desmethylmirtazapine, desmethylsertraline, O-desmethylvenlafaxine, was developed and validated. The developed method includes solid-phase extraction followed by derivatization with Heptafluorobutyric Anhydride. For all analytes, LOD and LOQ were 1.50 and 5.00ng/mL, respectively, and the calibration curves were linear within the dynamic range of 5.00-500.0ng/mL (R²≥0.990). The absolute recovery was found to be ≥86.3 % for all analytes. The accuracy (%Er) was found to range between -6.58 and 6.18 %, whereas the precision (%RSD) was less than 10.9 % for all analytes. The developed method was successfully applied to vitreous humor samples from 43 blood positive cases for antidepressant drugs. Whenever antidepressant drugs were detected in blood, they were also detected in the respective vitreous humor samples. The vitreous humor/blood concentration ratios were also calculated and were found to range from 0.04-7.07. Citalopram, mirtazapine, and its metabolite desmethylmirtazapine as well as venlafaxine and its metabolite O-desmethylvenlafaxine were the most identified substances in these samples (n≥4) and their results were better statistically evaluated. Our results suggest that vitreous humor could be an appropriate matrix for the determination of antidepressants in postmortem toxicology.

Optimization and validation of simultaneous analyses of ecgonine, cocaine, and seven metabolites in human urine by gas chromatography-mass spectrometry using a one-step solid-phase extraction

The presence of ecgonine in urine has been proposed as an appropriate marker of cocaine use. Only a few methods have been published for their determination along with cocaine and the rest of its metabolites. Due to their high polarity and consequent solubility in water, these have low recoveries, which is why it is necessary to increase the sensitivity, by the formation of hydrochloric salts or multiderivatization of the analytes or by performing two solid-phase extractions (SPEs), considerably increasing the time and cost of the analysis. This work describes a fast and fully validated procedure for the simultaneous detection and quantification of ecgonine, ecgonine-methyl-ester, benzoylecgonine, nor-benzoylecgonine, m-hydroxybenzoylecgonine, cocaethylene, cocaine, norcocaine, and norcocaethylene in human urine (500 μL) using one SPE and simple derivatization. Separation and quantification were achieved by gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) in selected-ion monitoring mode. Quantification was performed by the addition of deuterated analogs as internal standards. Calibration curves were linear in the adopted ranges, with determination coefficients higher than 0.99. The lower limits of quantification ranged from 2.5 to 10 ng/mL. The intra- and inter-day precision, calculated in terms of relative standard deviation, were 1.2%-14.9% and 1.8%-17.9%, respectively. The accuracy, in terms of relative error, was within a ± 16.4% interval. Extraction efficiency ranged from 84% to 103%. Compared with existing methods, the procedure described herein is fast, since only one SPE is required, and cost-effective. In addition, this method provides a high recovery for ecgonine, resulting in a better alternative to the previously published methods.

Cocaine toxicological findings in cases of violent death in Sao Paulo city - Brazil

Violence is a dreadful phenomenon spread throughout the world, resulting in unfortunate events that can ultimately cause death. It is known that some countries play a much worrying role in this scenario than others. Brazil is one of them. The present work has focused on identifying the use of cocaine in 105 postmortem cases arriving at the Institute of Legal Medicine of Sao Paulo (IML-SP), the largest Brazilian city. Both blood and hair samples have been analyzed through ultra-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) in order to distinguish between recent or chronic cocaine use. The purpose of this work was to evaluate the proportion of cocaine use amongst violent individuals whose violence has ultimately led to their death. In order to do so, two previous methods, validated in-house, based on methanolic extraction for hair and protein precipitation for blood, have been used for this purpose and the final residue was analyzed through UPLC-ESI-MS/MS system. When looking at the demographics from the 105 postmortem cases analyzed, the results have shown the most critical age range to be between 18 and 25 years old and the least frequent between 37 and 45 years old. Gender wise, a rather extreme difference was found as 97 of the individuals were men and finally, considering the manner of death, the four-category criteria established appear to be fairly similar with 34 cases related to general violence and risk behavior, 26 to drug abuse suspicion, 23 to homicide resulting from opposition to police intervention and 22 to possible suicide.

Rapid analysis of cocaine and metabolites in urine using microextraction in packed sorbent and GC/MS

Cocaine is still one of the most abused drugs worldwide and, as such, it is often screened for in driving-under-the-influence or workplace drug - testing scenarios. A large number of samples have usually to be processed in those situations, and this requires fast and simple extraction procedures for the detection and quantification of the drugs. The present work describes an ultrafast and fully validated procedure for the simultaneous detection and quantification of cocaine and its two main metabolites, ecgonine methyl ester and benzoylecgonine, in urine using microextraction by packed sorbent and GC-MS. A small sample volume (200 μL) was used, and a fast extraction procedure together with a microwave-assisted derivatization (800 W, 2 min) allowed the quantification of all analytes in a range of 25 to 1000 ng/mL (r ² > 0.99). Inter-day precision revealed coefficients of variation (CVs) lower than 10% for all analytes at the tested concentration levels, with an accuracy within a ±7% interval, with the exception of EME's lowest calibrator (±17%). Intra-day CVs were lower than 15% at the studied concentration levels, with a mean relative error within a ±13% interval. Recoveries ranged from 14.5 to 37.2% (EME), 67.0 to 83.3% (cocaine), and 24.6 to 43.5% (BEG), allowing the limits of detection and quantification to be set at 25 ng/mL for all compounds. Graphical Abstract Schematized analysis of cocaine and metabolites in urine by MEPS- GC/MS.

Vitreous humor analysis for the detection of xenobiotics in forensic toxicology: a review

Vitreous humor (VH) is a gelatinous substance contained in the posterior chamber of the eye, playing a mechanical role in the eyeball. It has been the subject of numerous studies in various forensic applications, primarily for the assessment of postmortem interval and for postmortem chemical analysis. Since most of the xenobiotics present in the bloodstream are detected in VH after crossing the selective blood-retinal barrier, VH is an alternative matrix useful for forensic toxicology. VH analysis offers particular advantages over other biological matrices: it is less prone to postmortem redistribution, is easy to collect, has relatively few interfering compounds for the analytical process, and shows sample stability over time after death. The present study is an overview of VH physiology, drug transport and elimination. Collection, storage, analytical techniques and interpretation of results from qualitative and quantitative points of view are dealt with. The distribution of xenobiotics in VH samples is thus discussed and illustrated by a table reporting the concentrations of 106 drugs from more than 300 case reports. For this purpose, a survey was conducted of publications found in the MEDLINE database from 1969 through April 30, 2015.