Quantitative estimation of alpha-PVP metabolites in urine by GC-APCI-QTOFMS with nitrogen chemiluminescence detection based on parent drug calibration

Corrigendum: Forensic Science International Vol. 288 Pages: 327-327 DOI: 10.1016/j.forsciint.2018.05.015 Published: JUL 2018Gas chromatography (GC) hyphenated with nitrogen chemiluminescence detection (NCD) and quadrupole time-of-flight mass spectrometry (QTOFMS) was applied for the first time to the quantitative analysis of new psychoactive substances (NPS) in urine, based on the N-equimolar response of NCD. A method was developed and validated to estimate the concentrations of three metabolites of the common stimulant NPS alpha-pyrrolidinovalerophenone (alpha-PVP) in spiked urine samples, simulating an analysis having no authentic reference standards for the metabolites and using the parent drug instead for quantitative calibration. The metabolites studied were OH-alpha-PVP (M1), 2 ''-oxo-alpha-PVP (M3), and N,N-bis-dealkyl-PVP (2-amino-1-phenylpentan-1-one; M5). Sample preparation involved liquid-liquid extraction with a mixture of ethyl acetate and butyl chloride at a basic pH and subsequent silylation of the sec-hydroxyl and prim-amino groups of M1 and M5, respectively. Simultaneous compound identification was based on the accurate masses of the protonated molecules for each compound by QTOFMS following atmospheric pressure chemical ionization. The accuracy of quantification of the parent-calibrated NCD method was compared with that of the corresponding parent-calibrated QTOFMS method, as well as with a reference QTOFMS method calibrated with the authentic reference standards. The NCD method produced an equally good accuracy to the reference method for alpha-PVP, M3 and M5, while a higher negative bias (25%) was obtained for M1, best explainable by recovery and stability issues. The performance of the parent-calibrated QTOFMS method was inferior to the reference method with an especially high negative bias (60%) for M1. The NCD method enabled better quantitative precision than the QTOFMS methods To evaluate the novel approach in casework, twenty post-mortem urine samples previously found positive for alpha-PVP were analyzed by the parent calibrated NCD method and the reference QTOFMS method. The highest difference in the quantitative results between the two methods was only 33%, and the NCD method's precision as the coefficient of variation was better than 13%. The limit of quantification for the NCD method was approximately 0.25 mg/mL in urine, which generally allowed the analysis of alpha-PVP and the main metabolite M1. However, the sensitivity was not sufficient for the low concentrations of M3 and M5. Consequently, while having potential for instant analysis of NPS and metabolites in moderate concentrations without reference standards, the NCD method should be further developed for improved sensitivity to be more generally applicable. (c) 2018 Elsevier B.V. All rights reserved.Peer reviewe

Quantitative Estimation of 38 Illicit Psychostimulants in Blood by GC-APCI-QTOFMS with Nitrogen Chemiluminescence Detection Based on Three External Calibrators

A method was developed for quantitative estimation of illicit psychostimulants in blood, with an emphasis on new psychoactive substances, based on gas chromatography nitrogen chemiluminescence detection coupled with atmospheric pressure chemical ionization quadrupole time-of-flight mass spectrometry (GC-NCD-APCI-QTOFMS). Quantitative estimation relied on the NCD's N-equimolar response to nitrogen, using amphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and methylenedioxypyrovalerone as external calibrators for prim-, sec- and tert- amines, respectively. After spiking with 38 stimulants at 3 concentration levels, the donor blood samples were submitted to liquid-liquid extraction at a basic pH followed by acylation with trifluoroacetic anhydride. All but 3 psychostimulants could be analyzed with a limit of quantification (LOQ) of 0.05 mg/L. At LOQ, the coefficient of variation (CV) values for between-day accuracy was 62.3-143.3% (mean, 93.5%; median, 88.5%) and precision 6.6-22.4% (mean, 15.8%; median, 16.1%). In addition, 11 post-mortem blood samples, containing 0.08-2.4 mg/L of amphetamine (n = 5), methamphetamine (n = 4) or MDMA (n = 4), were analyzed by the GC-NCD-APCI-QTOFMS method, and the results were compared with an established electron ionization GC-MS method with appropriate calibration. The agreement between the 2 methods was 62.5-117.3%. Regarding identification, the APCI source permitted detection of the intact precursor ion, or the respective acylation product, for all of the measured compounds. The GC-NCD-APCI-QTOFMS method developed here enables instant quantitative estimation of illicit psychostimulants in blood at reasonable accuracy, without the necessity of possessing the true reference standards for each analyte.Peer reviewe

Toxic lifespan of the synthetic opioid U-47,700 in Finland verified by re-analysis of UPLC-TOF-MS data

U-47,700 is a synthetic opioid that emerged on the novel psychoactive substance market a few years ago. After incorporating the substance into the urine UPLC-TOF-MS screening used in post-mortem toxicology, the drug was detected in 10 autopsy cases within routine case work. In all cases, the cause of death was accidental poisoning by U-47,700 alone or in combination with other psychoactive substances. The concentration of U-47,700 in the blood samples ranged between 0.15-2.0 mg/L with a median of 0.30 mg/L. In one of the cases with a U-47,700 concentration of 0.27 mg/L, no other psychoactive substances were detected. The stored TOF-MS analytical data from the year preceding the incorporation of U-47,700 into the screening was reprocessed in order to search for more positive cases. The data-independent acquisition of the original screening allowed for retrospective re-analysis of the full-scan data without additional experiments on the actual sample. The retrospective data-analysis revealed two additional cases positive for U-47,700. The first mention of U-47,700 on a Finnish internet discussion forum was in March 2015. After having been detected in several death cases, the drug was put under national control in November 2016 and the last fatality occurred in 2017. The toxic lifespan of U-47,700 thus lasted for approximately 2 years in Finland. Forensic and clinical laboratories need to rapidly adjust their screening procedures in order to adapt to the continuously expanding field of novel psychoactive substances. Retrospective data-analysis is a practical tool for monitoring the emergence of new substances onto the market. (C) 2019 Elsevier B.V. All rights reserved.Peer reviewe

Development of a GC-APCI-QTOFMS library for new psychoactive substances and comparison to a commercial ESI library

Gas chromatography coupled to atmospheric pressure chemical ionization quadrupole time-of-flight mass spectrometry (GC-APCI-QTOFMS) was evaluated for the identification of new psychoactive substances (NPS). An in-house high mass resolution GC-APCI-QTOFMS test library was developed for 29 nitrogen-containing drugs belonging mostly to synthetic stimulants. The library was based on 12 intra-day measurements of each compound at three different collision energies, 10, 20 and 40 eV. The in-house library mass spectra were compared to mass spectra from a commercial library constructed by liquid chromatography-electrospray ionization (LC-ESI) QTOFMS. The reversed library search scores between the in-house GC-APCI library and the commercial LC-ESI library were compared once a week during a 5-week period by using data measured by GC-APCI-QTOFMS. The protonated molecule was found for all drugs in the full scan mode, and the drugs were successfully identified by both libraries in the targeted MS/MS mode. The GC-APCI library score averaged over all collision energies was as high as 94.4/100 with a high repeatability, while the LC-ESI library score was also high (89.7/100) with a repeatability only slightly worse. These results highlight the merits of GC-APCI-QTOFMS in the analysis of NPS even in situations where the reference standards are not immediately available, taking advantage of the accurate mass measurement of the protonated molecule and product ions, and comparison to existing soft-ionization mass spectral libraries.Peer reviewe

Femoral blood concentrations of flualprazolam in 33 postmortem cases

Flualprazolam is a novel designer benzodiazepine, structurally related to alprazolam, flubromazolam and triazolam. In the last couple of years, it has been frequently detected in seizures and in forensic cases in Sweden and Finland. However, there is a lack of published blood concentrations for the drug, which presents difficulties when assessing its relevance for the cause of death. A quantitative method for the determination of flualprazolam in post-mortem blood was developed and validated, and subsequently used to analyse samples from 33 deaths previously screened as testing positive for flualprazolam in Sweden and Finland. Most of the cases in the study were accidental deaths (61 %) or suicides (18 %). The median (range) flualprazolam concentration was 18.0 (3.0-68) ng/g. The majority of the deceased were male (82 %) and the median age was 30 years. The median age in the Swedish cases was significantly higher (35 years) than in the Finnish cases (23 years) (p <0.05). Poly-drug use and particularly the concomitant use of flualprazolam and opioids were very common in the study population. Most of the cases that were positive for flualprazolam were fatal poisonings by a drug (N = 23), and in 13 cases, flualprazolam was implicated in the cause of death. Combining the resources of two countries in which all post-mortem toxicology is centralised provided a more comprehensive insight into the toxicology of flualprazolam. Research on novel psychoactive substances, such as flualprazolam, is required in order to be able to provide scientific evidence on the risks of these new substances for drug administration and potential users. (C) 2019 Elsevier B.V. All rights reserved.Peer reviewe

Single-calibrant quantification of seized synthetic opioids by liquid chromatography-chemiluminescence nitrogen detection

Drug seizures involving a wide variety of emerging new psychoactive substances (NPS) call for new approaches for instant quantification and valuation. Liquid chromatography-chemiluminescence nitrogen detection (LC-CLND) was used in the quantification of opioids with a single secondary standard (caffeine), utilizing the detector's equimolar response to nitrogen. The mean N-equimolarity of CLND for ten fentanyl derivatives and U-47700 by the present LC-CLND method was 96.4% (range 91-101%). The furanylfentanyl samples consisted of 112 powdery samples with a mean (median, range) hydrochloride purity of 13% (4.9%, 0.08-100%). The purity distribution of the furanylfentanyl samples was distinctly bipartite, showing only lower than 9% (NI = 98) and higher than 60% (N=14) purities. The carfentanil samples consisted of eight brownish sticky samples with a mean (median, range) hydrochloride purity of 0.064% (0.063%, 0.052-0.092%). The U-47700 samples consisted of seven powdery samples with a mean (median, range) hydrochloride purity of 89.0% (100%, 51-100%). The present application to synthetic opioid analysis widens the scope of the established LC-CLND method, previously found useful for single-calibrant quantification of stimulant/hallucinogenic and cannabinoid type of NPS. (C) 2019 Elsevier B.V. All rights reserved.Peer reviewe

Purity estimation of seized stimulant-type new psychoactive substances without reference standards by nitrogen chemiluminescence detection combined with GC-APCI-QTOFMS

Purity assessment of seized material containing new psychoactive substances (NPS) is complicated without appropriate primary reference standards. Here we present a method for fast quantitative estimation of stimulant-type NPS with use of secondary reference standards, based on gas chromatography nitrogen chemiluminescence detection coupled with atmospheric pressure chemical ionization quadrupole time-of-flight mass spectrometry (GC-NCD-APCI-QTOFMS). Quantification was based on the detector’s N-equimolar response to nitrogen and using two external nitrogen-containing calibrators, MDMA for prim- and sec- amines and α-PVP for tert- amines. Sample preparation involved dissolving the seized powdery material in an organic solvent mixture followed by acylation with N-methyl-bis-trifluoroacetamide (MBTFA). The method’s between-day accuracy and precision over a five-day period was measured for twenty-eight stimulants: the grand mean equimolarity was 91.9% (CV 5.5%), as compared with primary reference standards. The GC-NCD-APCI-QTOFMS method was applied to the purity estimation of forty-two seized powder samples previously found to contain stimulant-type NPS by appropriate methods. The quantitative results were compared to those obtained by an established method relying on liquid chromatography chemiluminescence detection (LC-CLND), the latter using caffeine as an external calibrator. The mean difference of purity values between the methods was 8.1% (range 0.4 - 26.7%). The presented method might find use as a tool for instant purity assessment in forensic laboratories.Peer reviewe

Simultaneous identification and quantification of new psychoactive substances in blood by GC-APCI-QTOFMS coupled to nitrogen chemiluminescence detection without authentic reference standards

A novel platform is introduced for simultaneous identification and quantification of new psychoactive substances (NPS) in blood matrix, without the necessity of using authentic reference standards. The instrumentation consisted of gas chromatography (GC) coupled to nitrogen chemiluminescence detection (NCD) and atmospheric pressure chemical ionization quadrupole time-of-flight mass spectrometry (APCI-QTOFMS). In this concept, the GC flow is divided in appropriate proportions between NCD for single-calibrant quantification, utilizing the detector's equimolar response to nitrogen, and QTOFMS for accurate mass-based identification. The principle was proven by analyzing five NPS, bupropion, desoxypipradrol (2-DPMP), mephedrone, methylone, and naphyrone, in sheep blood. The samples were spiked with the analytes post-extraction to avoid recovery considerations at this point. All the NPS studies produced a protonated molecule in APCI resulting in predictable fragmentation with high mass accuracy. The N-equimolarity of quantification by NCD was investigated by using external calibration with the secondary standard caffeine at five concentration levels between 0.17 and 1.7 mg/L in blood matrix as five replicates. The equimolarity was on average 98.7 %, and the range of individual equimolarity determinations was 76.7-130.1 %. The current analysis platform affords a promising approach to instant simultaneous qualitative and quantitative analysis of drugs in the absence of authentic reference standards, not only in forensic and clinical toxicology but also in other bioanalytical applications.Peer reviewe