Detection and quantification of etomidate and metomidate in human hairs by ultraperformance liquid chromatography with triple quadrupole mass spectrometry (UPLC-MS/MS).

PURPOSE: Intravenous narcotic agents, such as etomidate and metomidate, has been widely spread and abused in the world, including in Korea and China; thus, it is important to establish validated and sensitive analytical method for these compounds. Human hair as a biological sample has various advantages, including a wide detection window of drugs, compared to other typical samples, such as urine and blood in investigation. The purpose of this communication is to develop a reliable and useful method for the simultaneous detection and quantification of etomidate and metomidate in human hair samples by ultraperformance liquid chromatography combined with triple quadrupole mass spectrometry (UPLC-MS/MS), and to apply it for authentic samples in abuse cases. METHODS: The hair samples were washed with a detergent solution, followed by with water and acetone. After drying, they were cut into approximately 2 mm sections and then ground to powder by a low-temperature grinder. The 20 mg of hair powder plus internal standard in 1 mL of methanol was vortexed and then centrifuged to obtain the supernatant layer, followed by subjecting to analysis. RESULTS: The coefficient of determination (r2) values of the calibration curves of etomidate and metomidate in the hair samples were both more than 0.99 in the range of 1-500 ng/mg and 1-500 pg/mg, respectively. The limits of detection and lower limits of quantification were 0.5 and 1 pg/mg, respectively, for the both target compounds. Other tested validation data were all satisfactory. Etomidate and metomidate could be detected in the all hair samples and cigarette oil, which were seized by the police. The concentrations of etomidate and metomidate obtained from 10 samples from suspects were 5.48-45.7 ng/mg and 3.60-377 pg/mg, respectively. The concentrations of etomidate and metomidate in the cigarette oil were 95.8 µg/mg and 2.8 µg/mg, respectively. CONCLUSIONS: In this study, a simple and reliable analytical method for etomidate and metomidate in the human hair has been established. To the best of our knowledge, this is the first report to establish a method for the simultaneous detection and quantification of etomidate and metomidate in the human hair, and to apply it to authentic samples seized in authentic cases.

Simple quantification of propofol and its metabolites in blood and urine using gas chromatography-tandem mass spectrometry (GC-MS/MS).

An analytical method which was used for the simultaneous detection and quantification of propofol and its metabolites in human blood and urine by gas chromatography-tandem mass spectrometry (GC-MS/MS) was newly established and applied to authentic human samples obtained from the deceased. The QuEChERS method was employed, and then analyzed by GC-MS/MS. We separately used sulfatase and ß-glucuronidase to hydrolyze the urine sample and calculated the increase of propofol and 4-hydroxypropofol before and after the hydrolysis. The results of urinary concentrations in urine from the subject were: 4.88 µg/mL for propofol, 0.53 µg/mL for 4-hydroxypropofol, 3.35 µg/mL for propofol-glucuronide, 0.31 µg/mL for the total concentration of 1-(2,6-diisopropyl-1,4-quinol)-glucuronide plus 4-(2,6-diisopropyl-1,4-quinol)-glucuronide, and 0.39 µg/mL for 4-(2,6- diisopropyl-1,4-quinol)-sulfate. The lower limit of quantification was 10 ng/mL for all determined compounds; the extraction recoveries were not less than 57.2 %. Intraday and interday precisions and accuracies were all less than 10 %. The calibration curves for propofol and 4-hydroxypropofol in human urine showed the correlation values of not less than 0.999; propofol and 4-hydroxypropofol in blood also presented good linearities in the concentration ranges of 0.1-10 µg/mL. The two compounds had good stability within 7 days at 25, 4, and -20 ℃. To our knowledge, this is the first trial to establish a simple and reliable method to simultaneously detect and quantify of propofol and its phase I and II metabolites in human blood and urine samples by GC-MS/MS.

Quantification of nimetazepam and its metabolite in human hair samples using liquid chromatography-tandem mass spectrometry: Case report.

Nimetazepam (marketed brand names; Erimin and Lavol) is an intermediate acting benzodiazepine derivative, which was widely used mainly in East and Southeast Asian region countries including Japan, Malaysia, Brunei, the Philippines, Thailand, Indonesia, Hong Kong, Singapore and China. Nimetazepam and its metabolite 7-aminonimetazepam were quantified from human hair samples by liquid chromatography tandem-mass spectrometry (LC-MS/MS), under selective reaction monitoring mode. Using diazepam-d5 as an internal standard, the concentration of nimetazepam and its metabolite 7-aminonimetazepam could be determined by matrix matched calibration method. Extraction of the target compounds was performed by using methanol, followed by evaporation and being concentrated with nitrogen. The Limit of quantification concentrations of nimetazepam and its metabolite 7-aminonimetazepam in hair samples were both 25 pg/mg by established method. The concentrations of nimetazepam in hair samples obtained from 2 users were 27.4, and 22.0 pg/mg, respectively; the concentrations of 7-animonimetazepam in hair samples were 54.2 and 29.1 pg/mg, respectively. In our study, the 7-aminonimetazepam concentrations in hair was higher than those of nimetazepam in the authentic hair samples. To our knowledge, this is the first report to establish the detailed procedure for quantificating nimetazepam and 7-aminonimetazepam in human hair by LC-MS/MS.

Quantification of the benzimidazole opioid analog isotonitazene in human hair using liquid chromatography-tandem mass spectrometry.

Benzimidazole opioids were originally developed from the late 1950s to 1970s as analgesics for medical use, although a lot of them could not be approved as licit medicines because of their severe side effects and physical dependence. Such benzimidazole opioid analogs as abused drug, however, have recently been found in illicit drug markets throughout the world. Isotonitazene is one such benzimidazole opioids, whose analgesic potency can be as much as 500 times greater than that of morphine, according to previous animal studies. In line with this potency, a couple of hundred fatalities related to it were reported to date. In this study, a well validated method for the quantification of isotonitazene in human hair samples using liquid chromatography (LC)-tandem mass spectrometry (MS/MS) was established, and could be applied to authentic samples which were seized by the police security bureau. Isotonitazene concentrations in the seized hair averaged 6.11 pg/mg. The LLOQ and LOD of this method were 1.25 and 2.5 pg/mg, respectively; the calibration curve of the substance in hair samples showed a good linearity in the concentration range of 2.5-250 pg/mg (r > 0.999); the extraction recovery rates were 87.3-105% in the tested range; the inter- and intra-day precisions and accuracies (%biases) were not greater than 9.09% for each determination. Isotonitazene in human hair showed good stability at room temperature and under dark storage conditions for 30 days. As for matrix effect in hair samples, moderate ion suppression of target substances could be found. This is the first report for the analysis of isotonitazene in human hair samples.

Quantification of a new recreational drug 2-methoxyqualone in human hair using gas chromatography-tandem mass spectrometry.

A method for identification and quantification of 2-methoxyqualone, an newly emerging quinazolinone derivative recreational drug, in human scalp hair was established using gas chromatography (GC)-tandem mass spectrometry (MS/MS). In this report, authentic cases are presented, in which the suspects were seized by police security bureau; the police in China requested our laboratory to identify and quantify the involved drug(s) of abuse in the hair samples of the suspects. After washing and cryo-grinding the authentic hair samples, the target compound was extracted with methanol, and the solvent layer was evaporated to dryness. The residue was reconstituted in methanol and analyzed by GC-MS/MS. 2-Methoxyqualone concentrations in the hair were between 35.1 and 116 pg/mg. The calibration curve of the substance in hair samples showed a good linearity in the concentration range of 10-1000 pg/mg (r > 0.998); the extraction recovery rate, 88.8-105.6 %; the interday and intraday precisions and accuracies (biases), not greater than 8.9 %. 2-Methoxyqualone in human hair had good stability under three different storage conditions at room (20 °C), refrigerated (4 °C) and frozen (- 20 °C) temperatures for at least 7 days. In the present report, simple and rapid quantification method for 2-methoxyqualone in human scalp hair have been established using GC-MS/MS and it could successfully be applied to authentic forensic toxicological cases. To our knowledge, this is the first report for quantification of 2-methoxyqualone in human hair samples.

A comparative study of postmortem distribution and postmortem diffusion of tramadol in rabbits.

In recent years, the cases of tramadol intoxication have become more frequent in many countries. However, most of the previous studies have been based on cases of tramadol intoxication, and the detailed information on the differences between postmortem distribution and diffusion of tramadol remains unclear. To investigate this issue systematically, we established a postmortem distribution model and two postmortem diffusion models. Then, gas chromatography-mass spectrometry (GC/MS) was used to measure the concentrations of tramadol in various biological specimens of fluids and tissues. In postmortem distribution, the results showed an uneven distribution of tramadol in various biological specimens, and the concentrations of tramadol in urine were significantly higher than those in other fluids. In postmortem diffusion, the results showed a dosage-dependent increase of tramadol concentration in most specimens; at all time points from 0.25 to 6 h after postmortem administration, the concentrations of tramadol in fluids were not significantly different from those in tissues, and the concentrations of tramadol in urine were lower than those in both tissues and other fluids in most time points. We recommend a quantitative examination of the specimens of both fluids and tissues to provide more evidence for the forensic identification, and the realization that there is a correlation between the concentrations of fluids and tissues is important for determining antemortem and postmortem administration of tramadol. This information can serve as ancillary data in inferring the contribution of a drug to death in cases of suspected tramadol poisoning.

The next addiction-causing drug class 4-quinazolinone derivatives: analyses of methaqualone analogs including recently discovered 2-methoxyqualone by different modes of mass spectrometry.

PURPOSE: The information on analytical methods for 4-quinazolinone recreational drugs, such as methaqualone, etaqualone and 2-methoxyqualone, is almost scant. In this study, product ion spectra of gas chromatography-tandem mass spectrometry (GC-MS/MS) with different collision energies were presented for these drugs. Because 2-methoxyqualone is a new recreational drug discovered in dubious tablets very recently, much more detailed data obtained by different types of mass spectrometry instruments, and quantification data of 2-methoxyqualone in the tablet together with its validation were demonstrated. METHODS: The methods for analyses were GC-MS/MS, high-resolution ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry and liquid chromatography-tandem mass spectrometry. RESULTS: The GC-MS/MS product ion spectra of the three compounds with different collision energies have not been reported before. They were very useful to tentatively identify unknown compounds. If a reference standard is available, the final identification and quantification can be achieved by measurements of product ion spectra and in selected reaction monitoring mode very easily by GC-MS/MS. The final identification and quantification for the new 2-methoxyqualone were performed in this way. The content of the compound was 69.8 ± 0.5% (w/w) in the tablet. Acetaminophen and caffeine coexisted in the tablet with approximate concentrations at 10 and 5%, respectively. CONCLUSIONS: In this article, we have presented product ion spectra of methaqualone, etaqualone and 2-methoxyqualone at different collision energies by GC-MS/MS for the first time. In addition, this is the first paper to describe the details of quantification of 2-methoxyqualone in the authentic seized product.

Quantitation of sibutramine in human hair using gas chromatography-isotope dilution tandem mass spectrometry.

PURPOSE: An analytical method for quantitation of sibutramine in human hair using gas chromatography (GC)-isotope dilution tandem mass spectrometry (MS/MS) was newly established. In this article, a case is presented, in which a 3.5-year-old male child accidentally ingested chocolate-like product containing sibutramine, showing various symptoms; he could survived the crisis. About 1 month after the incident, his scalp hair sample was subjected to analysis for the causative sibutramine. METHOD: After cryo-grinding for the hair sample, target compound was extracted with methanol, and the solvent layer was evaporated to dryness. The residue was reconstituted in methanol and analyzed by GC-MS/MS, using the selected reaction monitoring (SRM) mode with a deuterated isotope internal standard. RESULTS: The substance was identified as sibutramine; its concentration in the hair sample of the child was 58.6 pg/mg. The calibration curve of sibutramine in hair samples had a good linear relationship in the concentration range of 20-200 pg/mg (r > 0.99); the extraction recovery rate 85.2-91.8%; the interday and intraday precision and accuracy (bias) examined not greater than 9.6%. Sibutramine in human hair had good stability under 3 different storage conditions at room (20 °C), refrigerated (4 °C) and frozen ( - 20 °C) temperatures for at least 7 days. CONCLUSIONS: It should be expected that the method established in this study would contribute to rapid determinations of sibutramine. To our knowledge, this is the first report describing quantitation of sibutramine in an authentic human hair sample by GC-MS/MS.

Quantification of MDMB-4en-PINACA and ADB-BUTINACA in human hair by gas chromatography-tandem mass spectrometry.

PURPOSE: To test synthetic cannabinoid (SCs) in parent forms from living human, the hairs seems to be one of the best samples, because of the non-invasiveness upon their collection. The purpose of this study is to establish a method for quantification of MDMB-4en-PINACA and ADB-BUTINACA, the most recently abused SCs in hair samples, using gas chromatography-tandem mass spectrometry (GC-MS/MS). METHODS: The collected hair samples were washed with a detergent solution, following by water and acetone. After drying cutting them into about 2 mm sections, they were ground by a cryogenic grinder into powder. The 50-mg powder with internal standard(s) plus 1 mL methanol were vortexed, and centrifuged to obtain the supernatant layer. After its evaporation and reconstitution with 50 µL methanol, 1-µL aliquot of it was subjected to analysis. RESULTS: The standard calibration curves were created for both MDMB-4en-PINACA and ADB-BUTINACA in blank hair samples; good linear curves were obtained in the range of 20-20,000 pg/mg with correlation coefficients greater than 0.99. The limits of detection and limits of quantification were 10 and 20 pg/mg, respectively. Other validation parameters were all satisfactory. The concentrations of MDMB-4en-PINACA obtained from 3 authentic subjects and ADB-BUTINACA obtained from 3 authentic subjects were 26.2-806 pg/mg and 63.1-430 pg/mg, respectively. CONCLUSIONS: In the present article, the details of simple and rapid quantification of MDMB-4en-PINACA and ADB-BUTINACA in human scalp hair have been established. To our knowledge, this is the first report for quantification of SCs in hair samples by GC-MS/MS.

Analytical method for detection and quantification of new emerging drug etaqualone in human blood and urine by gas chromatography tandem mass spectrometry.

Analytical procedure for detection and quantification of etaqualone in human blood and urine using GC-MS/MS was established and applied to authentic human samples obtained from volunteers. A liquid-liquid extraction method was employed. Each 1.0 mL of blood or urine was alkalized and extracted with diethyl ether. The solvent layer was evaporated to dryness and reconstituted with methanol then analyzed by GC-MS/MS. linear relationships within the concentration range of 1-100 ng/mL were obtained in calibrators for both blood and urine, demonstrating correlation coefficients values being>0.999. For blood and urine samples, the intra-day assay precision and accuracy values are each less than 3.65%, 7.13%, and 6.02%, 9.12%; those values of the inter-day assay are each less than 1.82%, 6.74%, and 3.99%, 7.41%. The extraction recovery rates for etaqualone ranged from 98.7% to 106%. The lower limit of quantifications was 1.0 ng/mL in both blood and urine. Stabilities of etaqualone in blood and urine were satisfactory under various temperatures within 15 days. 8.51 and 2.06 ng/mL of etaqualone in blood and urine were detected at 4 h later oral ingestion; 6.91 and 3.94 ng/mL of etaqualone were also detected 30 min and 2 h later smoking from blood and urine.

Detection and quantification of psychotropic drug etaqualone in human hair using GC-MS/MS.

In this study, sensitive analytical procedure for detection and quantification of etaqualone in human hair samples using gas chromatography tandem mass spectrometry (GC-MS/MS) was newly established, and applied it to authentic human samples obtained from an abuser. In this method, the hair samples were treated with hydrochloric acid and then extracted with ethyl ether. The ether layer was dried in a warm water bath, and the residue was reconstituted in ethyl acetate, followed by GC-MS/MS analysis. Multiple reaction monitoring (MRM) mode was used for data collection, and quantitative analysis was performed using internal standard method. Good linear relationship within the concentration range of 1-100 pg/mg were obtained in calibrators for the hair samples showing its correlation coefficient value was 0.9993. The lower limit of quantitation in this study was 1 pg/mg and the recovery rate examined ranged from 100.4% to 108.5%. The intra-day precision and accuracy were less than 5.0% and 5.8%, respectively. The inter-day precision and accuracy were lower than 6.4% and 4.6%, respectively. Using this established method, etaqualone could be detected in the hair sample obtained from a suspected user to be level of 65.2 pg/mg. It should be expected that the method established in this study would contribute to rapid detection and identification of psychotropic drug etaqualone among multiple fields including forensic investigation, clinical application and of course public health matters.

Quantification of eucalyptol (1,8-cineole) in rat serum by gas chromatography-mass/mass spectrometry and its application to a rat pharmacokinetic study.

Eucalyptol (1,8-cineole) is a biologically active cyclic monoterpenoid. In a preliminary study, we used gas chromatography-mass spectrometry to detect eucalyptol in the serum and brain tissue of rats after oral administration. However, the absorption characteristics in vivo and pharmacokinetic parameters of eucalyptol have not been published to date. The present study aims to develop and validate a simple, sensitive GC-MS/MS method with quadrupole mass analyzer type for the quantitative analysis of eucalyptol in rat serum and apply it to a pharmacokinetic study. The assay showed linearity of concentration range from 50 to 5,000 pg/ml with a limit of quantitation of 50 pg/ml. Intra- and inter-day precision for eucalyptol were 4.4-13.0 and <15.0%, respectively, and accuracy was within 10% for quality control samples. The recovery and stability results showed that the method was accurate and stable for quantitative analysis. The developed analytical method was successfully applied to a pharmacokinetic study after a single oral administration of eucalyptol in rat subjects. The serum concentration-time profiles indicate that the absorption characteristics of eucalyptol after oral administration are similar to those for intravenous administration.

Supramolecular solvent (SUPRASs) extraction method for detecting benzodiazepines and zolpidem in human urine and blood using gas chromatography tandem mass spectrometry.

OBJECTIVE: A high-throughput and sensitive method using supramolecular solvent (SUPRASs) for detecting 9 benzodiazepines and zolpidem in human urine and blood by gas chromatography-tandem mass spectrometry (GC-MS/MS) was newly established and applied to authentic human urine and blood samples in this study. METHODS: Urine and blood samples were subjected to liquid-liquid extractions with supramolecular solvent mixture which consists of tetrahydrofuran and 1-hexanol. The solvent layer was evaporated to dryness by stream of nitrogen. The residue was reconstituted with methanol, and subjected to analysis by GC-MS/MS in multiple reaction monitoring (MRM) mode; internal standard method was employed for quantifying of each targeted compound. RESULTS: The regression equation has a good linear relationship with correlation coefficients for all tested compounds were not lower than 0.9991. The lower limits of the quantification ranged from 0.20 to 5 ng/mL for tested compounds in urine; Meanwhile, the lower limits of the quantification in this method ranged from 1 to 50 ng/mL for tested compounds in blood. These results showed that excellent reproducibility and satisfactory extraction recovery rates could be obtained for the established analytical method for 10 drugs in both blood and urine samples. CONCLUSION: The established method in this study was high-throughput, simple and sufficiently sensitive for determining of benzodiazepinesand zolpidem in human urine and blood. Therefore, this newly established method could be of use for qualitative and quantitative determination of such drugs in urine and blood samples either for clinical poisoning monitoring or for forensic identification.

Supramolecular Solvent Extraction-Gas Chromatography-Tandem Mass Spectrometry for Detection of Benzodiazepines in Urines / 法医学杂志

Objective To establish a method using supramolecular solvent and gas chromatography-tandem mass spectrometry （GC-MS/MS） to analyze 9 benzodiazepines in urines. Methods Urine samples containing 9 benzodiazepines reference substance were subjected to liquid-liquid extractions with supramolecular solvent, which consisted of tetrahydrofuran and 1-hexanol. The solvent layer was evaporated to dryness by stream of nitrogen. The residue was reconstituted with methanol, and GC-MS/MS analysis was performed on it. The way of data collection was multiple reaction monitoring （MRM） mode; internal standard method was employed for quantification. Results In urine samples, when the range of mass concentration was 1-100 ng/mL for diazepam, midazolam, flunitrazepam and clozapine, 5-100 ng/mL for lorazepam and alprazolam, 2-100 ng/mL for nitrazepam and clonazepam, and 0.2-100 ng/mL for estazolam, respectively, good linearities were obtained, correlation coefficients were 0.999 1-0.999 9, the lower limits of the quantifications ranged from 0.2 to 5 ng/mL, the extraction recovery rates were 81.12%-99.52%. The intra-day precision ［relative standard deviation （RSD）］ and accuracy （bias） were lower than 9.86% and 9.51%, respectively; the inter-day precision （RSD） and accuracy （bias） were lower than 8.74% and 9.98%, respectively. Nine drugs in urine samples showed good stability at ambient temperature and -20 ℃ within 15 days. The mass concentrations of alprazolam in urine samples obtained from 8 volunteers who took alprazolam tablets orally within 8-72 h after ingestions ranged from 6.54 to 88.28 ng/mL. Conclusion The supramolecular solvent extraction GC-MS/MS method for analysis of 9 benzodiazepines in urines provided by this study is simple, fast, accurate and sensitive, which can provide technical support for monitoring of poisoning by benzodiazepines for clinical treatment and judicial identification.

Postmortem distribution/redistribution of buformin in body fluids and solid tissues in an autopsy case using liquid chromatography-tandem mass spectrometry with QuEChERS extraction method.

An autopsy for a suicidal case of a male in his 40s, who had died of poisoning due to ingestion of a large amount of buformin, was performed at our department. Buformin is biganide class agent used for patients of diabetes mellitus, which can occasionally cause severe lactic acidosis. The autopsy was performed about 10 days after his death, and the direct cause of his death was judged as asphyxia due to the aspiration of stomach contents into the airway. The nine body fluids and eight solid tissues specimens were dealt with for investigating postmortem distribution/redistribution of buformin in a whole body; femoral vein blood, right and left heart blood, pericardial fluid, urine, bile, stomach contents, small intestine contents, cerebrospinal fluid, the brain, lung, heart muscle, liver, spleen, kidney and skeletal muscle were examined. For extracting buformin from specimens, a modified QuEChERS method including dispersive solid-phase extraction was employed, followed by the analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS). Buformin in various kinds of human matrices were quantified by the standard addition method in this study, which can overcome the matrix effects and recovery rates without use of blank human matrices. All concentrations of buformin in specimens examined in this case were extremely higher than those of previously reported poisoning cases. The concentrations of buformin in left and right heart blood and femoral vein blood specimens of this case were 399, 216 and 261µg/mL, respectively; although the direct cause of his death was judged as asphyxia due to occlusion of airway with stomach contents, the vomiting was thought to be provoked by buformin poisoning. In this study, marked differences of buformin concentrations between brain tissue and cerebral spiral fluids, and other specimens were observed, which suggested that its distribution was influenced also by blood-brain-barrier. Although a number of buformin poisoning cases were published so far, they gave sporadic data on its concentrations and/or distribution in some limited human specimens. This study is the first to describe detailed distribution/redistribution of buformin in a whole human body quantified by using LC-MS/MS.

Fatal zolpidem poisoning due to its intravenous self-injection: Postmortem distribution/redistribution of zolpidem and its predominant metabolite zolpidem phenyl-4-carboxylic acid in body fluids and solid tissues in an autopsy case.

We experienced a curious fatal case, in which a male in his 20s self-administered zolpidem intravenously. The victim was found dead lying on floor of his apartment room, with a tourniquet band and new injection marks on his right forearm. Nearby the body, a medical disposal syringe containing small-volume solution dissolving crushed zolpidem tablets was found. The postmortem interval was estimated at about two days. The direct cause of his death was judged as asphyxia due to the aspiration of stomach contents into the trachea and bronchi. The specimens dealt with were body fluids and solid tissues including femoral vein blood, right and left heart blood, pericardial fluid, urine, bile, stomach contents, the brain, lung, heart muscle, liver, spleen, kidney, pancreas and skeletal muscle. For the extractions of zolpidem, zolpidem phenyl-4-carboxylic acid, deuterated internal standards zolpidem-d7 and zolpidem phenyl-4-carboxylic acid-d4, a modified QuEChERS method was used, followed by the analysis by liquid chromatography-tandem mass spectrometry. Because this study included various kinds of human matrices with quite different properties, the standard addition method was most preferable to overcome the matrix effects and recovery rates, and also did not need to use blank human matrices for validation experiments. The concentration of zolpidem and its phenyl-4-carboxylic acid metabolite in various specimens tested were generally extreme higher than those of reported fatal cases, supporting that the victim had died of intravenous zolpidem injection. The concentrations of zolpidem in femoral vein blood and right and left heart blood specimens in the present case were 9.55, 28.5 and 46.9µg/mL, respectively, which far exceeded estimated fatal levels. The present study also showed the postmortem distribution/redistribution of zolpidem and its phenyl-4-carboxylic acid metabolite in 15 body fluid and solid tissue specimens including stomach contents. Although a number of published literatures dealt with zolpidem poisoning cases due to oral ingestion of the drug, this is the first report on fatal intravenous zolpidem injection case and postmortem distribution of zolpidem and its predominant metabolite.

Identification and quantification of metabolites of AB-CHMINACA in a urine specimen of an abuser.

We experienced an autopsy case in which the cause of death was judged as poisoning by multiple new psychoactive substances, including AB-CHMINACA, 5-fluoro-AMB and diphenidine [Forensic Toxicol. 33 (2015): 45-53]. Although unchanged AB-CHMINACA could be detected from 8 solid tissues, it could neither be detected from blood nor urine specimens. In this article, we obtained eight kinds of reference standards of AB-CHMINACA metabolites from a commercial source. The AB-CHMINACA metabolites from the urine specimen of the abuser were extracted by a modified QuEChERS method and analyzed by liquid chromatography-tandem mass spectrometry before and after hydrolysis with ß-glucuronidase. Among the eight AB-CHMINACA metabolites tested, only 2 metabolites could be identified in the urine specimen of the deceased. After hydrolysis with ß-glucuronidase, the concentrations of the two metabolites were not increased, suggesting that the metabolites were not in the conjugated forms. The metabolites detected were 4-hydroxycyclohexylmethyl AB-CHMINACA (M1), followed by N-[[1-(cyclohexylmethyl)-1H-indazol-3-yl]carbonyl]-l-valine (M3). Their concentrations were 52.8 ± 3.44 and 41.3 ± 5.04 ng/ml (n=10) for M1 and M3, respectively. Although there is one preceding report showing the estimations of metabolism of AB-CHMINACA without reference standards, this is the first report dealing with exact identification using reference standards, and quantification of M1 and M3 in an authentic urine specimen.