Stability of Ethyl Glucuronide, Ethyl Sulfate, Phosphatidylethanols and Fatty Acid Ethyl Esters in Postmortem Human Blood

Lipidomics in forensic science: a comprehensive review of applications in drugs, alcohol, latent fingermarks, fire debris, and seafood authentication

Forensic science, an interdisciplinary field encompassing the collection, examination, and presentation of evidence in legal proceedings, has recently embraced lipidomics as a valuable tool. Lipidomics, a subfield of metabolomics, specializes in the analysis of lipid structures and functions, offering insights into biological processes that can aid forensic investigations. While not a substitute for DNA analysis in personal identification, lipidomics complements this technique by focusing on small biological molecules, with distinct sample requirements. This review comprehensively explores the current applications of lipidomics in forensic science. The review commences with an introduction to the concept and historical background of lipidomics, subsequently delving into its utilization in diverse areas such as drug analysis, ethyl alcohol and substitute assessment, latent fingermark detection, fire debris analysis, and seafood authentication. By showcasing the various biological materials and methods employed, this review underscores the potential of lipidomics as a powerful adjunct in forensic investigations.

Postmortem/dynamic distribution of ethanol and its nonoxidative metabolites in poisoned rabbits

Nonoxidative ethanol metabolites have been reported as ethanol biomarkers in clinical and forensic cases. However, their forensic toxicokinetics are still unclear. The study aimed to simultaneously research the postmortem distribution and dynamic distribution of ethanol and its nonoxidative metabolites in 62 poisoned rabbits. Firstly, 32 rabbits were randomly divided into three groups and sacrificed after three doses ethanol, and their organs were collected to study the postmortem distribution of ethanol and its nonoxidative metabolites. The results showed that the distribution trends of ethanol and its nonoxidative metabolites were basically same between different groups, and ethanol could be better detected by collecting body fluids, while the nonoxidative metabolites could be better detected by collecting the heart, liver, kidney and testis. Secondly, 30 rabbits after 1/2LD50 ethanol intragastric administration were sacrificed at 10 time points, and their organs were collected to study the dynamic distribution of ethanol and its nonoxidative metabolites. The results showed the concentrations of ethanol and its nonoxidative metabolites increased with time and then decreased. All analytes could be detected in all samples within 8 h, with the exception of ethyl oleate, which kept high level in muscle and vitreous humor, and could be detected within 4 h.

Influence of Drugs and Toxins on Decomposition Dynamics: Forensic Implications

Drug and toxin-related deaths are common worldwide, making it essential to detect the postmortem concentration of various toxic substances at different stages of decomposition in a corpse. Indeed, determining the postmortem interval (PMI) and cause of death in an advanced stage of decomposed corpses has been a significant challenge in forensic investigations. Notably, the presence of drugs or toxins can have a significant impact on the microbial profile, potentially altering the succession of microbial communities and subsequent production of volatile organic compounds (VOCs), which, in turn, affect insect colonization patterns. This review aims to highlight the importance of investigating the interactions between drugs or toxins, microbial succession, VOC profiles, and insect behavior, which can provide valuable insights into forensic investigations as well as the ecological consequences of toxins occurring in decomposition. Overall, the detection of drugs and other toxins at different stages of decomposition can yield more precise forensic evidence, thereby enhancing the accuracy of PMI estimation and determination of the cause of death in decomposed remains.

Stability of diazepam's phase II metabolites in dried blood spots on filter paper

Phase II metabolites play an important role in diazepam-related cases. The study aimed to assess the stability of diazepam's phase II metabolites in dried blood spots on filter paper.

METHODS

A piece of filter paper was spotted with 100 µL of whole blood (added 1% sodium fluoride as needed) obtained from participant who received 5 mg diazepam orally, air dried for 2 h at room temperature, and then stored at different conditions. Whole spots were cut at 0.1 cm from the outer edge of blood spots at post-consumption time-points of prior (zero), 5, 16, 35, 61, 120 days and 1, 1.5 years. Analytes were extracted with methanol/water mixture (8:2, v/v) and determined using HPLC-MS/MS. Decomposition rules were analyzed by a statistical software "SPSS".

RESULTS

Temazepam glucuronide remained stable (0.5-18.6% loss) at 20 ℃ and at 20 ℃ with 1% sodium fluoride for 16 days, while it was unstable after 5 days at 4 ℃ (21.1-26.2% loss) and - 20 ℃ (28.9 - 34.4% loss). After 35 days, temazepam glucuronide concentrations began to fluctuate significantly under all conditions, and an obvious increase (290.4-355.1%) was observed in 1.5 years. Oxazepam glucuronide was always unstable after 5 days, the percentage loss was even 100% when it was stored for 61 days and 1.5 years.

CONCLUSIONS

Dried blood spots on ordinary filter paper are recommended to be stored at 20 ℃ or 20 ℃ with 1% sodium fluoride within 16 days. Samples should be analyzed immediately or stored in sterile and dry media.

Validation of a new method for the detection of Ethyl glucuronide in larvae of Lucilia sericata as a marker of ante-mortem alcohol consumption

Larvae and insects are an important and alternative biological matrix in the development anpost-mortem forensic toxicology. They are very useful when conventional matrices are not available, in particular when the loss of biological fluids, due to the decomposition of corpses or to a traumatic death, occurs. The purpose of this study is to develop and validate an analytical method in Ultra High-Performance Liquid Chromatography at High Resolution Mass Spectrometry (HPLC/HR-MS) for the research and quantification of Ethyl glucuronide (EtG) on larvae. The criteria taken into consideration for the validation are linearity, quantitation limits (LOD and LLOQ), accuracy, precision, carryover, interferences and ionization suppression/enhancement. The method was shown to be linear within the tested range, with a coefficient of determination higher than 0.99. LOD was 2 pg mg-1, while LLOQ was 5 pg mg-1. Accuracy, precision and ionization/suppression enhancement fulfilled the criteria indicated in the guidelines used for the validation. The establishment and validation of this method allowed the identification of Ethyl glucuronide on the larvae of Lucilia sericata (Calliphoridae) of a subject found death in an advanced state of decomposition.

Pathogenic mechanisms and regulatory factors involved in alcoholic liver disease

Alcoholism is a widespread and damaging behaviour of people throughout the world. Long-term alcohol consumption has resulted in alcoholic liver disease (ALD) being the leading cause of chronic liver disease. Many metabolic enzymes, including alcohol dehydrogenases such as ADH, CYP2E1, and CATacetaldehyde dehydrogenases ALDHsand nonoxidative metabolizing enzymes such as SULT, UGT, and FAEES, are involved in the metabolism of ethanol, the main component in alcoholic beverages. Ethanol consumption changes the functional or expression profiles of various regulatory factors, such as kinases, transcription factors, and microRNAs. Therefore, the underlying mechanisms of ALD are complex, involving inflammation, mitochondrial damage, endoplasmic reticulum stress, nitrification, and oxidative stress. Moreover, recent evidence has demonstrated that the gut-liver axis plays a critical role in ALD pathogenesis. For example, ethanol damages the intestinal barrier, resulting in the release of endotoxins and alterations in intestinal flora content and bile acid metabolism. However, ALD therapies show low effectiveness. Therefore, this review summarizes ethanol metabolism pathways and highly influential pathogenic mechanisms and regulatory factors involved in ALD pathology with the aim of new therapeutic insights.

Biomarkers of moderate alcohol intake and alcoholic beverages: a systematic literature review

The predominant source of alcohol in the diet is alcoholic beverages, including beer, wine, spirits and liquors, sweet wine, and ciders. Self-reported alcohol intakes are likely to be influenced by measurement error, thus affecting the accuracy and precision of currently established epidemiological associations between alcohol itself, alcoholic beverage consumption, and health or disease. Therefore, a more objective assessment of alcohol intake would be very valuable, which may be established through biomarkers of food intake (BFIs). Several direct and indirect alcohol intake biomarkers have been proposed in forensic and clinical contexts to assess recent or longer-term intakes. Protocols for performing systematic reviews in this field, as well as for assessing the validity of candidate BFIs, have been developed within the Food Biomarker Alliance (FoodBAll) project. The aim of this systematic review is to list and validate biomarkers of ethanol intake per se excluding markers of abuse, but including biomarkers related to common categories of alcoholic beverages. Validation of the proposed candidate biomarker(s) for alcohol itself and for each alcoholic beverage was done according to the published guideline for biomarker reviews. In conclusion, common biomarkers of alcohol intake, e.g., as ethyl glucuronide, ethyl sulfate, fatty acid ethyl esters, and phosphatidyl ethanol, show considerable inter-individual response, especially at low to moderate intakes, and need further development and improved validation, while BFIs for beer and wine are highly promising and may help in more accurate intake assessments for these specific beverages.

Ethyl sulfate in blood shows the potential to distinguish alcoholic death and postmortem alcohol instillation

Alcohol is often found in the blood of the deceased. To cover up the true cause of victim's death, postmortem instillation of alcohol occurs in some criminal cases. Explaining the finding of alcohol is extremely vital in forensic practice. This study aims to evaluate whether ethyl glucuronide (EtG) and ethyl sulfate (EtS) in blood and vitreous humor (VH) can be used to distinguish alcoholic death and postmortem alcohol instillation. Saline or 12.6 g/kg ethanol (antemortem alcohol poisoning group) was introduced into rabbits' stomachs 2 h before sacrificed. Same amount of ethanol was introduced into rabbits' stomachs at 0 h, 0.5 h, 1 h and 2 h after death in four subgroups of postmortem alcohol instillation group, respectively. Cardiac blood and VH were collected at 10 min, 4 h, 10 h and 24 h after death in blank and antemortem alcohol poisoning group, and after instillation of alcohol in postmortem alcohol instillation group. Blood was also collected at 34 h. Ethanol and EtG levels in blood and VH and EtS in VH in antemortem alcohol poisoning group were overlapped with those in postmortem alcohol instillation group. The contents of EtG and EtS in blood in antemortem alcohol poisoning group (mean ≥ 7.833 μg/mL for EtG and ≥ 19.990 μg/mL for EtS) were much higher than those in postmortem alcohol instillation group (mean ≤ 0.118 μg/mL for EtG and ≤ 0.091 μg/mL for EtS), but apparent decomposition was observed in EtG, which might lead to misinterpretation. Blood EtS showed better stability and could be used to distinguish alcoholic death and postmortem alcohol instillation.

Determination of Ethyl Glucuronide and Ethyl Sulfate in Dried Blood Spots by UHPLC-MS-MS: Method Validation and Assessment of Ethanol Exposure in Postmortem Samples from Road Traffic Victims

The determination of ethyl glucuronide (EtG) and ethyl sulfate (EtS) in blood has been proposed in clinical and forensic applications to identify recent alcohol consumption. Also, there is a growing interest on the use of dried blood spots (DBS) in toxicological analysis, allowing increased stability of the analytes and simplifying sample transportation and storage. This study presents the development and validation of a method for quantifying EtG and EtS in DBS using ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS-MS). The DBS samples were extracted with a mixture of methanol and acetonitrile (80:20 v/v) and analyzed using UHPLC-MS-MS with electrospray source in negative mode, after separation with a fluoro-phenyl stationary phase. Validation was performed according to the Scientific Working Group for Forensic Toxicology (SWGTOX) guidelines, with calibrations ranging from 0.10 to 18 µg/mL for EtG and 0.02 to 6 µg/mL for EtS. The analytes were stable in DBS stored from -20 to 45°C for 21 days. The method was successfully applied to capillary and venous DBS samples from 20 volunteers after ethanol ingestion and to DBS samples from 99 fatal victims of road traffic injuries. Capillary DBS was comparable to venous DBS and fresh whole blood in Passing-Bablok and Bland-Altman analysis, with correlation coefficients >0.91 (P < 0.001) for all comparisons. In postmortem application, the DBS EtG and EtS analysis indicated positive exposure to ethanol in 72.7% of the cases (EtG: 0.10-24.0 µg/mL and EtS: 0.03-4.11 µg/mL). The identification of ethanol consumption from blood alcohol concentrations (BACs) and EtG/EtS in DBS was in agreement in 98.6% of positive and 96.3% of negative cases (kappa 0.877, P < 0.001), indicating a high level of concordance with BAC in assessing alcohol use in postmortem samples.

Estimating the time of last drinking from blood ethyl glucuronide and ethyl sulphate concentrations

The determination of length of time from the last drinking is critical for cases like drunk driving, sexual assault victims, and also postmortem suspected poisoning cases. The study was aimed to established a method of estimating the time of last drinking through the pharmacokinetic study of conjugation metabolites of alcohol in blood after a single oral dose. Twenty-six volunteers (14 males) consumed alcohol with food at a fixed dose of 0.72 g/kg after fasting for 12 h. Five milliliters of blood were collected 120 h after the start of drinking, and all samples were analyzed with headspace-gas chromatography and high-performance liquid chromatography–tandem mass spectrometry. The time point of last drinking was estimated through the relationship between the concentration ratio of ethyl glucuronide to ethyl sulphate and the length of time after drinking. Pharmacokinetic parameters were analyzed by a pharmacokinetic software DAS according to the non-compartment model. A good correlation model was obtained from the relationship between concentration ratio of ethyl glucuronide to ethyl sulphate in blood and the time of alcohol use, and the margin of error was mostly lower than 10%. The time of maximum concentration, maximum concentration, and elimination half-life of ethyl glucuronide in blood were 4.12 ± 1.07 h, 0.31 ± 0.11 mg/L and 2.56 ± 0.89 h; the time of maximum concentration, maximum concentration, and elimination half-life of ethyl sulphate in blood were 3.02 ± 0.70 h, 0.17 ± 0.04 mg/L, and 2.04 ± 0.76 h. The study established a potential method to estimate the length of time after a moderate oral dose, and provided pharmacokinetic parameters of ethyl glucuronide and ethyl sulphate in Chinese population.

Decomposition kinetics and postmortem production of hydrogen sulfide and its metabolites

BACKGROUND

Hydrogen sulfide (H₂S), an endogenous gas, can also be generated from organics putrefaction. It is difficult for suspected cases of H₂S poisoning to determine whether H₂S in specimens is ingested by antemortem poisoning or generated from organics putrefaction. The aim of this study was to find the biomarkers of acute H₂S poisoning via comparing the concentrations of H₂S and its metabolites over time in specimens.

METHODS

The H₂S-spiked blood and blank blood group were established. The decomposition kinetics and the postmortem production of H₂S were studied due to organics putrefaction. The specimens were placed under 4 conditions of 37, 20, 4 and - 20 ℃. The content of H₂S in specimens was quantified by gas chromatography-mass spectrometry, and the contents of its metabolites (thiosulfate and trimethylsulfonium) were measured by liquid chromatography-mass spectrometry, and the variation of its concentration was evaluated.

RESULTS

In H₂S-spiked blood, H₂S decreased sharply in the initial stage at 37, 20 and 4 °C, and increased first and then decreased later; but it was relatively stable at - 20 °C. In spiked blood, thiosulfate was 9-fold higher than endogenous concentrations, which increased at first and then decreased during storage. Except for thiosulfate at 37 °C, H₂S and thiosulfate in blank blood both increased at first and then decreased in storage; but trimethylsulfonium (TMS) gradually decreased over time in both groups.

CONCLUSIONS

Thiosulfate is a reliable biomarker of acute H₂S poisoning at - 20℃ within 7 days. But H₂S, because of instability and volatility, is not an ideal poisoning marker. TMS is not an appropriate biomarker due to extremely low concentration in blood.

Effects of postmortem interval, putrefaction, diabetes, and location of death on the analysis of ethyl glucuronide and ethyl sulfate as ethanol biomarkers of antemortem alcohol consumption

This study evaluated the forensic value of ethanol biomarkers ethyl glucuronide (EtG) and ethyl sulfate (EtS) under different conditions, including diabetes mellitus, drug abuse, and advanced decomposition. In addition, we explored whether ethanol, EtG, or EtS formation occurred in patients who died as a result of diabetes mellitus. Fifty-two routine postmortem cases were divided into three groups. Group 1 included only the post-mortem cases in which at least blood samples were available (n=47). Group 2 included all cases with positive BAC (n=28). Group 3 included the cases with negative BAC while information surrounding the cases suspected antemortem alcohol consumption and cases that tested negative for ethanol but positive for EtG and EtS. We analyzed multiple bodily fluid specimens, including the vitreous humor, for ethanol biomarker analysis and accurately identified antemortem ethanol consumption or postmortem ethanol synthesis. We also determined the utility of urine samples for analyzing ethanol and its metabolites in putrefaction cases. If no urine sample was available at autopsy due to urination before death or diabetes-associated glucosuria, vitreous humor samples were an appropriate alternative for ethanol biomarker testing. We observed postmortem ethanol synthesis in diabetic individuals even with a short postmortem interval (PMI), however, glucose did not increase postmortem ethanol production in individuals with diabetes under appropriate preservation. The shorter the PMI, the better the ethanol source can be determined. Postmortem ethanol production occurred in all body fluid specimens analyzed herein, including the vitreous humor. EtG and EtS levels were stable and provided accurate insight into ethanol sources, even in cases of postmortem ethanol production. While the present study focused on the use of vitreous humor for the analysis, it is expected such samples may not be available in cases of advanced decay. In cases where no other bodily fluid specimens are available, solid tissue specimens are highly preferred.

Investigations into the stability of 17 psychoactive drugs in a "simulated postmortem blood" model

In the postmortem environment some drugs and metabolites may degrade due to microbial activity, even forming degradation products that are not produced in humans. Consequently, under- or over-estimation of perimortem drug concentrations or even false negatives are possible when analyzing postmortem specimens. Therefore, understanding whether medications may be susceptible to microbial degradation is critical in order to ensure that reliable detection and quantitation of drugs and their degradation products is achieved in toxicology screening methods. In this study, a "simulated postmortem blood" model constructed of antemortem human whole blood inoculated with a broad population of human fecal microorganisms was used to investigate the stability of 17 antidepressant and antipsychotic drugs. Microbial communities present in the experiments were determined to be relevant to postmortem blood microorganisms by 16S rRNA sequencing analyses. After 7 days of exposure to the community at 37 °C, drug stability was evaluated using liquid chromatography coupled with diode array detection (LC-DAD) and with quadrupole time of flight mass spectrometry (LC-QTOF-MS). Most of the investigated drugs were found to be stable in inoculated samples and non-inoculated controls. However, the 1,2-benzisothiazole antipsychotics, ziprasidone and lurasidone, were found to degrade at a rate comparable to the known labile control, risperidone. In longer experiments (seven to twelve months), where specimens were stored at -20 °C, 4 °C, and ambient temperature, N-dealkylation degradation products were detected for many of the drugs, with greater formation in specimens stored at -20 °C than at 4 °C.

Modeling Postmortem Ethanol Production/Insights into the Origin of Higher Alcohols

The forensic toxicologist is challenged to provide scientific evidence to distinguish the source of ethanol (antemortem ingestion or microbial production) determined in the postmortem blood and to properly interpret the relevant blood alcohol concentration (BAC) results, in regard to ethanol levels at death and subsequent behavioral impairment of the person at the time of death. Higher alcohols (1-propanol, 1-butanol, isobutanol, 2-methyl-1-butanol (isoamyl-alcohol), and 3-methyl-2-butanol (amyl-alcohol)) are among the volatile compounds that are often detected in postmortem specimens and have been correlated with putrefaction and microbial activity. This brief review investigates the role of the higher alcohols as biomarkers of postmortem, microbial ethanol production, notably, regarding the modeling of postmortem ethanol production. Main conclusions of this contribution are, firstly, that the higher alcohols are qualitative and quantitative indicators of microbial ethanol production, and, secondly that the respective models of microbial ethanol production are tools offering additional data to interpret properly the origin of the ethanol concentrations measured in postmortem cases. More studies are needed to clarify current uncertainties about the origin of higher alcohols in postmortem specimens.

Frequency of postmortem ethanol formation in blood, urine and vitreous humor - Improving diagnostic accuracy with the use of ethylsulphate and putrefactive alcohols

PURPOSE

This study aimed to compare the frequency of postmortem ethanol formation in blood, urine and vitreous humor according to negative ethylsulphate (EtS) in blood or positive putrefactive alcohols (PA's) in either medium. Furthermore, it aimed to evaluate the interpretational value of calculated ethanol ratios in relation to EtS and PA results.

METHODS

Blood ethanol positive forensic cases were included; one dataset consisting of 2504 cases with EtS analysed in blood and another dataset with 8001 cases where PA's were analysed.

RESULTS

PA's were found in 24.4% of cases. EtS was negative in 15.3%, 9.4% and 7.4% of cases that were positive for ethanol in blood, urine and vitreous humor, respectively. In EtS negative cases, the concentrations of ethanol in blood, urine and vitreous humor were lower than 0.20 g/kg in 51.3%, 67.4% and 77.8%, respectively. It was 1.0 g/kg or higher in blood in 4.2% of cases. More EtS negative and PA positive cases were seen in central compared to peripheral blood. Ethanol ratios between urine or vitreous humor and blood were significantly lower in both EtS negative and PA positive cases, but large variations were observed.

CONCLUSION

EtS and PA analysis improve the diagnostic accuracy of ethanol in postmortem cases. Postmortem ethanol formation in vitreous humor and urine were both more frequent than expected and we recommend the analysis of ethanol primarily in peripheral blood if available.

Development and validation of an analytical method for the simultaneous determination of the alcohol biomarkers ethyl glucuronide, ethyl sulfate, N-acetyltaurine, and 16:0/18:1-phosphatidylethanol in human blood

As alcohol is the most common addictive substance worldwide, it is inevitable to advance the established research. New and more substantial analytical methods can be applied to reply to complex questions in legal or forensic contexts. Therefore, an analytical method for the simultaneous determination of four different alcohol biomarkers-ethyl glucuronide, ethyl sulfate, N-acetyltaurine, and 16:0/18:1-phosphatidylethanol-in human blood was developed, validated, and verified. Despite the different chemical properties of the analytes, a specific determination via HPLC-MS/MS was achieved using a novel type of a Phenomenex Luna® Omega Sugar column. Furthermore, all criteria for a successful validation were fulfilled according to forensic guidelines. The method proved to be linear and demonstrates selectivity and sufficient sensitivity for every biomarker. LODs obtained with this method of 2.6 ng/ml (EtG), 4.7 ng/ml (EtS), 12.5 ng/ml (NAcT), and 6.9 ng/ml (PEth) were in an acceptable range for routine applications, and the stability of all analytes over a range of 12 h is given. The verification of the new developed method was performed with authentic samples. Thus, whole blood and postmortem samples were analyzed to obtain information about the drinking behavior, which can answer complex questions regarding alcohol consumption.

Modeling microbial ethanol production by S. aureus, K. pneumoniae, and E. faecalis under aerobic/anaerobic conditions - applicability to laboratory cultures and real postmortem cases

A quite intriguing subject being intensively researched in the forensic toxicology field is the source of postmortem determined blood ethanol concentration: antemortem ingestion or postmortem microbial production. Our previous research on microbial ethanol production has reported a quantitative relationship between the ethanol and the higher alcohols and 1-butanol produced by Escherichia coli, Clostridium perfrigens, and Clostridium sporogenes. In this contribution, we continue our research reporting on the following: (i) the patterns of ethanol, higher alcohols, and 1-butanol production by the microbes Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecalis (all being aerobic/facultative anaerobic species, common corpse's colonizers, and ethanol producers), under controlled laboratory conditions, (ii) the mathematical modeling, with simple mathematical equations, of the correlation between ethanol concentration and the other studied alcohols' concentrations, by performing multiple linear regression analysis of the results, and (iii) the applicability of the constructed models in microbial cultures developed under different temperature than that used to build the models, in denatured blood cultures and in real postmortem cases. The aforementioned alcohols were proved to be all indicators of ethanol production, both in qualitative and quantitative terms. 1-Propanol was the most significant alcohol in modeling microbial ethanol production, followed by methyl-butanol. The K. pneumoniae's models achieved the best scoring in applicability (E < 40%) compared to the S. aureus and E. faecalis models, both at laboratory microbial cultures at 37 °C and real postmortem cases. Overall, a noteworthy accuracy in estimating the microbial ethanol in cultures and autopsy blood is achieved by the employed simple linear models.

Determination of Ethyl Glucuronide and Ethyl Sulfate in Human Whole Blood and Vitreous Humor by LC-MS-MS and Applications to the Interpretation of Postmortem Ethanol Findings

Identifying the source of ethanol in a decedent remained a complicated problem for forensic toxicologists because of postmortem ethanol formation. As ethanol's non-oxidative metabolites, ethyl glucuronide (EtG) and ethyl sulfate (EtS) have the potential to distinguish between antemortem ethanol consumption and postmortem ethanol formation, due to their high sensitivity and selectivity. In the current study, a simple and quick liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the determination of EtG and EtS in human whole blood and vitreous humor (VH). A total of 20 μL of the sample was precipitated by methanol, and the analytes were detected by LC-MS/MS in a run of 6 min. This method achieved high sensitivity (limits of detection: 2 ng/mL for both EtG and EtS), with linearity in the range of 5-10,000 ng/mL in both whole blood and VH. Deviations in accuracy, inter- and intra-day precision were all lower than 15% at three quality control levels. Subsequently, this method was applied to 62 real forensic cases. Only blood samples were available in 52 cases. Paired blood and VH samples were present in 10 cases. The concentrations of EtG and EtS in blood were in the range of 0-22,264.8 ng/mL and 0-2,126.0 ng/mL, respectively. In one case with both blood and VH, the blood ethanol concentration was 1.22 mg/mL, with EtG and EtS both below limits of quantification (5 ng/mL) in VH, and no EtG and EtS found in whole blood. The results suggested that EtG and EtS were useful markers for the interpretation of ethanol resource in postmortem blood and VH.

Modeling postmortem ethanol production by C. albicans: Experimental study and multivariate evaluation

In previous research, we modeled the ethanol production by certain bacteria under controlled experimental conditions in an attempt to quantify the production of microbial postmortem ethanol in cases where other alcohols were co-detected. This contribution on the modeling of postmortem ethanol production by Candida albicans is complementary to these previous studies. Τhis work aimed to study ethanol, higher alcohols (1-propanol, isobutanol, 2-methyl-1-butanol and 3-methyl-1-butanol), and 1-butanol production by Candida albicans: (i) in different culture media (Brain Heart Infusion, BHI and, Sabouraud Dextrose Broth, SDB), (ii) under mixed aerobic/anaerobic or strict anaerobic conditions, and (iii) at different temperatures (37 °C, 25 °C and, 4 °C), and develop simple mathematical models, resulted from fungal cultures at 25 °C, to predict the microbially produced ethanol in correlation with the other alcohols. The applicability of the models was tested in the C. albicans cultures in BHI and SDB media at 37 °C, in denatured human blood at 25 °C, acidic and neutral with different concentrations of additional glucose, in acidic denatured blood diluted with dextrose solution and in blood from autopsy cases. The received results indicated that the C. albicans models could apply in cases where yeasts have been activated in blood with elevated glucose levels. Overall, the in vitro ethanol production by C. albicans in blood depended on temperature, time, glucose (or carbohydrate) content, pH of the medium and endogenous changes in the medium composition through time. Our results showed that methyl-butanol is the most significant indicator of fungal ethanol production, followed by the equally important isobutanol and 1-propanol in qualitative and quantitative terms.

Quantitative Determination of Ethyl Glucuronide and Ethyl Sulfate in Postmortem and Antemortem Whole Blood Using Phospholipid Removal 96-Well Plate and UHPLC-MS-MS

Postmortem ethanol formation is a well-known problem in forensic toxicology. Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are ethanol metabolites that can be used to distinguish antemortem alcohol intake from postmortem formation of ethanol and in addition can be a helpful tool in assessment of the hip-flask defense. To an aliquot of 100 µL whole blood, internal standard (IS) and water was added before protein precipitation treatment (PPT) with ice-cold acetonitrile (ACN). The supernatants were filtered through a 96-well phospholipid removal plate, evaporated to dryness and reconstituted in 150 µL water/ACN/formic acid (FA). Identification of compounds was performed using multiple reaction monitoring (MRM) in negative mode. Gradient elution was performed on a C18 column with methanol (MeOH) and 0.1% FA. The run time was 4.5 min, and 0.5 µL was injected on an ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS-MS) instrument. Linearity was achieved (coefficient of determination (R²) ≥ 0.999) for EtG in the range of 0.089 to 22 mg/L (0.40–100 µM) and EtS 0.025 to 6.3 mg/L (0.20–50 µM). The limit of quantification (LOQ) was 0.067 mg/L (0.30 µM) for EtG and 0.019 mg/L (0.15 µM) for EtS. Between assay accuracy was –15% to 8% and precision reported as relative standard deviation (RSD) was ≤ 4.5%. Precision, estimated as the RSD of the concentration difference between results from two independent analyses of authentic whole blood samples, was ≤ 6.7%. Recovery was ≥ 61% for EtG and ≥ 77% for EtS and matrix effects (ME) were 99% to 103%. Method comparison was carried out with a previously used UHPLC–MS-MS method, and satisfactory agreement was achieved, and external proficiency testing control samples had z-score < ± 1. The method has been used in routine work for more than 4 years analyzing about 6,000 antemortem and postmortem whole blood samples and has proven to be robust and reliable.

Phosphatidylethanol for Monitoring Alcohol Use in Liver Transplant Candidates: An Observational Study

Liver transplantation remains an essential procedure for many patients suffering from alcoholic liver disease. Alcohol use monitoring remains paramount all through the stages of this complex process. Direct alcohol biomarkers, with improved specificity and sensibility, should replace traditional indirect markers. Phosphatidylethanol (PEth) has been recently tested in alcoholic liver disease patients, but more evidence is needed, especially in comparison with other direct biomarkers. We conducted an observational study among patients awaiting liver transplantation. We analyzed Peth in blood, ethylglucuronide (EtG) in hair and urine and ethylsulphate (EtS) in urine, using mass spectrometry methods. In addition, transaminases, and self-reports were analyzed. A total of 50 patients were included (84% men, mean age 59 years (SD = 6)). 18 patients (36%) screened positive for any marker. Self-reports were positive in 3 patients. EtS was the biomarker with more positive screens. It also was the most frequently exclusive biomarker, screening positive in 7 patients who were negative for all other biomarkers. PEth was positive in 5 patients, being the only positive biomarker in 2 patients. It showed a false negative in a patient admitting alcohol use the previous week and screening positive for EtG and EtS. Hair EtG was positive in 3 patients who had negative Peth, EtG. EtG did not provide any exclusive positive result.A combination of biomarkers seems to be the best option to fully ascertain abstinence in this population. Our study suggest EtS might also play a significant role.

Evaluation and review of ways to differentiate sources of ethanol in postmortem blood

Accurate determination of a person's blood alcohol concentration (BAC) is an important task in forensic toxicology laboratories because of the existence of statutory limits for driving a motor vehicle and workplace alcohol testing regulations. However, making a correct interpretation of the BAC determined in postmortem (PM) specimens is complicated, owing to the possibility that ethanol was produced in the body after death by the action of various micro-organisms (e.g., Candida species) and fermentation processes. This article reviews various ways to establish the source of ethanol in PM blood, including collection and analysis of alternative specimens (e.g., bile, vitreous humor (VH), and bladder urine), the identification of non-oxidative metabolites of ethanol, ethyl glucuronide (EtG) and ethyl sulfate (EtS), the urinary metabolites of serotonin (5-HTOL/5-HIAA), and identification of n-propanol and n-butanol in blood, which are known putrefaction products. Practical utility of the various biomarkers including specificity and stability is discussed.

Interpol review of toxicology 2016-2019

This review paper covers the forensic-relevant literature in toxicology from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20.Papers%202019.pdf.

An LC-MS/MS method for comparing the stability of ethanol's non-oxidative metabolites in dried blood spots during 90 days

Problems of stability were found for biomarkers of alcohol consumption: ethyl glucuronide (EtG), ethyl sulfate (EtS), phosphatidylethanols (PEths), and fatty acid ethyl esters (FAEEs) in whole blood. The purpose of this study was to establish a method for the determination of these four kinds of ethanol's non-oxidative metabolites in dried blood spots (DBS) by liquid chromatography tandem mass spectrometry (LC-MS/MS), and to evaluate their stability. In this method, 50 μL of human blood was spotted onto a filter paper for DBS analysis. Samples were extracted by methanol, reconstituted by 2-propanol, and injected into the LC-MS/MS system. Limits of detection were among 0.5-50 ng/mL, and deviations in accuracy and precision were all lower than 15% at three quality control levels. The stability of the four kinds of ethanol non-oxidative metabolites in DBS was investigated during a 90-day range under three temperatures, -20 °C, 4 °C, and 25 °C. EtG and EtS showed a high level of stability in DBS in the 90-day range, regardless of the temperature. FAEEs were unstable after three days. PEths showed stability within 15 days in postmortem DBS and 60 days in antemortem DBS, respectively, at all temperatures.