A comprehensive approach to detecting multitudinous bioactive peptides in equine plasma and urine using hydrophilic interaction liquid chromatography coupled to high resolution mass spectrometry

Bioactive peptides possess pharmacological effects and can be illicitly used in sports. To deter such misuse, an untargeted method using high resolution mass spectrometry (HRMS) has been developed for comprehensive detection of multitudinous exogenous peptides in equine plasma and urine. Forty‐four peptides were extracted using mixed‐mode solid‐phase extraction (SPE) from plasma and urine, separated with a hydrophilic interaction liquid chromatography (HILIC) column, and detected on an HRMS instrument. Ammonium formate as a mobile phase additive had effects on HILIC retention and charge state distribution of the peptides. The acetonitrile percentage in the reconstitution solution affected the solubility of peptide neat standards and peptides in plasma and urine extracts differently. The stability of the peptides in plasma at ambient temperature was assessed. The limit of detection (LOD) was 10–50 pg/mL for most of the peptides in plasma, and ≤ 500 pg/mL for the remaining. LOD was 100–400 pg/mL for the majority of the analytes in urine, and ≤ 4000 pg/mL for the others. The method was used successfully to analyze incurred plasma and urine samples from research horses administered dermorphin. Even in the absence of reference standards, dermorphin metabolites (aFGYPS‐NH₂, YaFG, and YaF) were identified. These results demonstrate that data generated with this method can be retrospectively reviewed for peptides that are unknown at the time of sample analysis without requiring re‐analysis of the sample. This method provides a powerful novel tool for detection of numerous bioactive peptides and their metabolites in equine plasma and urine for doping control.     

Urinary detection of conjugated and unconjugated anabolic steroids by dilute‐and‐shoot liquid chromatography‐high resolution mass spectrometry

Anabolic androgenic steroids (AAS) are an important class of doping agents. The metabolism of these substances is generally very extensive and includes phase‐I and phase‐II pathways. In this work, a comprehensive detection of these metabolites is described using a 2‐fold dilution of urine and subsequent analysis by liquid chromatography‐high resolution mass spectrometry (LC‐HRMS). The method was applied to study 32 different metabolites, excreted free or conjugated (glucuronide or sulfate), which permit the detection of misuse of at least 21 anabolic steroids. The method has been fully validated for 21 target compounds (8 glucuronide, 1 sulfate and 12 free steroids) and 18 out of 21 compounds had detection limits in the range of 1–10 ng mL^?1 in urine. For the conjugated compounds, for which no reference standards are available, metabolites were synthesized in vitro or excretion studies were investigated. The detection limits for these compounds ranged between 0.5 and 18 ng mL^?1 in urine. The simple and straightforward methodology complements the traditional methods based on hydrolysis, liquid‐liquid extraction, derivatization and analysis by gas chromatography–mass spectrometry (GC‐MS) and liquid chromatography‐mass spectrometry (LC‐MS). Copyright © 2014 John Wiley & Sons, Ltd.     

UHPLC‐MS/MS and UHPLC‐HRMS identification of zolpidem and zopiclone main urinary metabolites and method development for their toxicological determination

Zolpidem and zopiclone (Z‐compounds) are non‐benzodiazepine hypnotics of new generation that can be used in drug‐facilitated sexual assault (DFSA). Their determination in biological fluids, mainly urine, is of primary importance; nevertheless, although they are excreted almost entirely as metabolites, available methods deal mainly with the determination of the unmetabolized drug. This paper describes a method for the determination in urine of Z‐compounds and their metabolites by ultra‐high‐pressure liquid chromatography/tandem mass spectrometry (UHPLC‐MS/MS) and UHPLC coupled with high resolution/high accuracy Orbitrap® mass spectrometry (UHPLC‐HRMS). The metabolic profile was studied on real samples collected from subjects in therapy with zolpidem or zopiclone; the main urinary metabolites were identified and their MS behaviour studied by MS/MS and HRMS. Two carboxy‐ and three hydroxy‐ metabolites, that could be also detected by gas chromatography/mass spectrometry (GC‐MS) as trimethylsylyl derivatives, have been identified for zolpidem. Also, at least one dihydroxilated metabolite was detected. As for zopiclone, the two main metabolites detected were N‐demethyl and N‐oxide zopiclone. For both substances, the unmetabolized compounds were excreted in low amounts in urine. In consideration of these data, a UHPLC‐MS/MS method for the determination of Z‐compounds and their main metabolites after isotopic dilution with deuterated analogues of zolpidem and zopiclone and direct injection of urine samples was set up. The proposed UHPLC‐MS/MS method appears to be practically applicable for the analysis of urine samples in analytical and forensic toxicology cases, as well as in cases of suspected DFSA. Copyright © 2013 John Wiley & Sons, Ltd.     

A high‐throughput and broad‐spectrum screening method for analysing over 120 drugs in horse urine using liquid chromatography–high‐resolution mass spectrometry

A high‐throughput method has been developed for the doping control analysis of 124 drug targets, processing up to 154 horse urine samples in as short as 4.5 h, from the time the samples arrive at the laboratory to the reporting deadline of 30 min before the first race, including sample receipt and registration, preparation and instrument analysis and data vetting time. Sample preparation involves a brief enzyme hydrolysis step (30 min) to detect both free and glucuronide‐conjugated drug targets. This is followed by extraction using solid‐supported liquid extraction (SLE) and analysis using liquid chromatography–high‐resolution mass spectrometry (LC–HRMS). The entire set‐up comprised of four sets of Biotage Extrahera automation systems for conducting SLE and five to six sets of Orbitrap for instrumental screening using LC–HRMS. Suspicious samples flagged were subject to confirmatory analyses using liquid chromatography–triple quadrupole mass spectrometry. The method comprises 124 drug targets from a spectrum of 41 drug classes covering acidic, basic and neutral drugs. More than 85% of the targets had limits of detection at or below 5 ng/mL in horse urine, with the lowest at 0.02 ng/mL. The method was validated for qualitative identification, including specificity, sensitivity, extraction recovery and precision. Method applicability was demonstrated by the successful detection of different drugs, namely (a) butorphanol, (b) dexamethasone, (c) diclofenac, (d) flunixin and (e) phenylbutazone, in post‐race or out‐of‐competition urine samples collected from racehorses. This method was developed for pre‐race urine testing in Hong Kong; however, it is also suitable for testing post‐race or out‐of‐competition urine samples, especially when a quick total analysis time is desired.     

Administration study of recombinant human relaxin‐2 in horse for doping control purpose

The insulin‐like peptide relaxin (RLX), an endogenous peptide hormone produced in human for pregnancy and reproduction, is also known to exert a range of physiological and pathological effects. Its use is banned in human sports, horseracing, and equestrian competitions due to its potential performance enhancing effect through vasodilation resulting in the increase of blood and oxygen supplies to muscles. Little is known about the biotransformation and elimination of RLX in horses. This paper describes an administration study of rhRLX‐2 and its elimination in horses, and the development of sensitive methods for the detection and confirmation of rhRLX‐2 in both horse plasma and urine by nano‐liquid chromatography/high resolution mass spectrometry (nano‐LC/HRMS) after immunoaffinity extraction with the objective of controlling the abuse of rhRLX‐2 in horses. The limits of detection in plasma and urine are 2 pg/mL and 5 pg/mL, respectively. Two thoroughbred geldings were each administered one dose of 10 mg rhRLX‐2 subcutaneously daily for 3 consecutive days. The rhRLX‐2 could be detected and confirmed in the plasma and urine samples collected 105 h and 80 h, respectively, after the last dose of administration. For doping control purposes, rhRLX‐2 ELISA could be used as a screening test to identify potential positive samples for further investigation using the nano‐LC/HRMS methods.     

Study of the in vitro and in vivo metabolism of the tryptamine 5‐MeO‐MiPT using human liver microsomes and real case samples

The synthetic tryptamine 5‐methoxy‐N‐methyl‐N‐isopropyltryptamine (5‐MeO‐MiPT) has recently been abused as a hallucinogenic drug in Germany and Switzerland. This study presents a case of 5‐MeO‐MiPT intoxication and the structural elucidation of metabolites in pooled human liver microsomes (pHLM), blood, and urine. Microsomal incubation experiments were performed using pHLM to detect and identify in vitro metabolites. In August 2016, the police encountered a naked man, agitated and with aggressive behavior on the street. Blood and urine samples were taken at the hospital and his premises were searched. The obtained blood and urine samples were analyzed for in vivo metabolites of 5‐MeO‐MiPT using liquid chromatography–high resolution tandem mass spectrometry (LC–HRMS/MS). The confiscated pills and powder samples were qualitatively analyzed using Fourier transform infrared (FTIR), gas chromatography–mass spectrometry (GC–MS), LC‐HRMS/MS, and nuclear magnetic resonance (NMR). 5‐MeO‐MiPT was identified in 2 of the seized powder samples. General unknown screening detected cocaine, cocaethylene, methylphenidate, ritalinic acid, and 5‐MeO‐MiPT in urine. Seven different in vitro phase I metabolites of 5‐MeO‐MiPT were identified. In the forensic case samples, 4 phase I metabolites could be identified in blood and 7 in urine. The 5 most abundant metabolites were formed by demethylation and hydroxylation of the parent compound. 5‐MeO‐MiPT concentrations in the blood and urine sample were found to be 160 ng/mL and 3380 ng/mL, respectively. Based on the results of this study we recommend metabolites 5‐methoxy‐N‐isopropyltryptamine (5‐MeO‐NiPT), 5‐hydroxy‐N‐methyl‐N‐isopropyltryptamine (5‐OH‐MiPT), 5‐methoxy‐N‐methyl‐N‐isopropyltryptamine‐N‐oxide (5‐MeO‐MiPT‐N‐oxide), and hydroxy‐5‐methoxy‐N‐methyl‐N‐isopropyltryptamine (OH‐5‐MeO‐MiPT) as biomarkers for the development of new methods for the detection of 5‐MeO‐MiPT consumption, as they have been present in both blood and urine samples.     

Investigation of the metabolism of the selective androgen receptor modulator LGD‐4033 in equine urine,plasma and hair following oral administration

LGD‐4033 is one of a number of selective androgen receptor modulators (SARMs) that are being developed by the pharmaceutical industry to provide the therapeutic benefits of anabolic androgenic steroids, without the less desirable side effects. Though not available therapeutically, SARMs are available for purchase online as supplement products. The potential for performance enhancing effects associated with these products makes them a significant concern with regards to doping control in sports. The purpose of this study was to investigate the metabolism of LGD‐4033 in the horse following oral administration, in order to identify the most appropriate analytical targets for doping control laboratories. LGD‐4033 was orally administered to two Thoroughbred horses and urine, plasma and hair samples were collected and analysed for parent drug and metabolites. LC‐HRMS was used for metabolite identification in urine and plasma. Eight metabolites were detected in urine, five of which were excreted only as phase II conjugates, with the longest detection time being observed for di‐ and tri‐hydroxylated metabolites. The parent compound could only be detected in urine in the conjugated fraction. Seven metabolites were detected in plasma along with the parent compound where mono‐hydroxylated metabolites provided the longest duration of detection. Preliminary investigations with hair samples using LC–MS/MS analysis indicated the presence of trace amounts of the parent compound and one of the mono‐hydroxylated metabolites. In vitro incubation of LGD‐4033 with equine liver microsomes was also performed for comparison, yielding 11 phase I metabolites. All of the metabolites observed in vivo were also observed in vitro.     

A high‐throughput LC‐MS/MS screen for GHRP in equine and human urine,featuring peptide derivatization for improved chromatography

The growth hormone releasing peptides (GHRPs) hexarelin, ipamorelin, alexamorelin, GHRP‐1, GHRP‐2, GHRP‐4, GHRP‐5, and GHRP‐6 are all synthetic met‐enkephalin analogues that include unnatural D‐amino acids. They were designed specifically for their ability to stimulate growth hormone release and may serve as performance enhancing drugs. To regulate the use of these peptides within the horse racing industry and by human athletes, a method is presented for the extraction, derivatization, and detection of GHRPs from equine and human urine. This method takes advantage of a highly specific solid‐phase extraction combined with a novel derivatization method to improve the chromatography of basic peptides. The method was validated with respect to linearity, repeatability, intermediate precision, specificity, limits of detection, limits of confirmation, ion suppression, and stability. As proof of principle, all eight GHRPs or their metabolites could be detected in urine collected from rats after intravenous administration. Copyright © 2014 John Wiley & Sons, Ltd.     

Metabolic profiling of isomeric aglycones central‐icaritin (c‐IT) and icaritin (IT) in osteoporotic rats by UPLC‐QTOF‐MS

The isomers, although of similarly chemical structures, have different pharmacological activities due to their metabolic processes in vivo. Central‐icaritin (c‐IT) and icaritin (IT) are isomers and major bioactive aglycones of the Herba Epimedii. In this study, we found that the anti‐osteoporotic effect of c‐IT was stronger than IT on bone structural changes in osteoporotic rats evaluated by Micro‐μCT with the parameters of bone mineral density (BMD), bone mineral content (BMC), tissue mineral content (TMC), and tissue mineral density (TMD). c‐IT treatment significantly increased the bone microarchitecture, compared with IT (p < 0.05). In order to explain their differences in anti‐osteoporosis, the metabolic profiling and pathways of c‐IT and IT in the plasma, bile, urine, and faeces of ovariectomized (OVX) rats were investigated by ultra‐performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC‐QTOF‐MS) after oral administration of c‐IT or IT (80 mg/kg). Finally, 59 metabolites of c‐IT and 43 metabolites of IT were identified by elucidating their corresponding quasimolecular ions and fragment ions. IT could be quickly absorbed into blood and reached a maximum plasma concentration, and then be rapidly conversed to its glucuronidation metabolites, most of which were excreted out by urine. Interestingly, the absorbed and conjugated speeds of c‐IT were slower than IT. The metabolic processes of c‐IT existed enterohepatic circulation, which decreased the metabolism and excretion rate of c‐IT, and prolonged the anti‐osteoporosis effect. Our findings provided evidence on the difference on metabolic profiles of c‐IT and IT in osteoporotic rats, which might shed new lights on improving anti‐osteoporotic effects of IT and c‐IT. Copyright © 2014 John Wiley & Sons, Ltd.     

Targeting misuse of 2‐amino‐N‐ethyl‐1‐phenylbutane in urine samples: in vitro–in vivo correlation of metabolic profiles and development of LC‐TOF‐MS method

A phenyethylamine derivative, 2‐amino‐N‐ethyl‐1‐phenylbutane (2‐AEPB), has recently been detected in doping control and drugs‐of‐abuse samples, and identified as a non‐labelled ingredient in a dietary supplement. To facilitate efficient control of this substance we have studied the in vitro metabolic behaviour of 2‐AEPB with human liver preparation, compared these results with in vivo pathways in human, and finally propose an analytical strategy to target the potential misuse of 2‐AEPB for toxicological, forensic and doping control purposes. The major in vitro formed metabolites originated from desethylation (M1) and monohydroxylation (M2). A minor metabolite with hydroxylation/N‐oxidation was also observed (M3). In vitro‐in vivo correlation was studied in an excretion study with a single, oral dose of 2‐AEPB‐containing supplement. An unmodified substance was the most abundant target compound and detected until the last point of sample collection (72 h), and the detection of M1 (40 h) and M2 (27 h) demonstrated good correlation to in vitro results. In the study with authentic cases (n = 6), 2‐AEPB and M1 were mainly found in free urinary fraction, whereas higher inter‐individual variability was observed for M2. It was predominantly conjugated and already within this limited number of cases, the ratio between glucuronide‐ and sulpho‐conjugated fractions varied significantly. As a conclusion, hydrolysis is not mandatory in the routine sample preparation, and as the separation can be based on either gas chromatography or liquid chromatography, this study verifies that routine mass spectrometric detection methods targeted to amphetamine derivatives can be easily extended to control the misuse of 2‐AEPB. Copyright © 2014 John Wiley & Sons, Ltd.     

Targeted and non‐targeted drug screening in whole blood by UHPLC‐TOF‐MS with data‐independent acquisition

High‐resolution mass spectrometry (HRMS) is widely used for the drug screening of biological samples in clinical and forensic laboratories. With the continuous addition of new psychoactive substances (NPS), keeping such methods updated is challenging. HRMS allows for combined targeted and non‐targeted screening. First, peaks are identified by software algorithms, and identifications are based on reference standard data. Attempts are made to identify the remaining unknown peaks with in silico and literature data. However, several thousand peaks remain where most are unidentifiable or uninteresting in drug screening. The aims of the study were to apply a combined targeted and non‐targeted screening approach to authentic driving‐under‐the‐influence‐of‐drugs (DUID) samples (n = 44) and further validate the approach using whole‐blood samples spiked with 11 low‐dose synthetic benzodiazepine analogues (SBAs). Analytical data were acquired using ultra‐high‐performance liquid chromatography coupled with a time‐of‐flight mass spectrometer (UHPLC‐TOF‐MS) with data‐independent acquisition (DIA). We present a combined targeted and non‐targeted screening, where peak deconvolution and filtering reduced the number of peaks to inspect by three orders of magnitude, down to four peaks per DUID sample. The screening allowed for tentative identification of metabolites and drugs not included in the initial screening; 3 drugs and 14 metabolites were tentatively identified in the authentic DUID samples. Running targeted‐screening true‐positive identifications through the filters retained 73% of identifications. In the non‐targeted screening, nine of the spiked SBAs were identified in the concentration range of 0.005–0.1 mg/kg, of which three were tentatively identified at concentrations below those reported in the literature. Copyright © 2016 John Wiley & Sons, Ltd.     

Solid‐phase extraction of small biologically active peptides on cartridges and microelution 96‐well plates from human urine

Currently liquid chromatography – mass spectrometry (LC‐MS) analysis after solid‐phase extraction (SPE) on weak cation‐exchange cartridges is a method of choice for anti‐doping analysis of small bioactive peptides such as growth hormone releasing peptides (GHRPs), desmoporessin, LHRH, and TB‐500 short fragment. Dilution of urine samples with phosphate buffer for pH adjustment and SPE on weak cation exchange microelution plates was tested as a means to increase throughput of this analysis. Dilution using 200 mM phosphate buffer provides good buffering capacity without affecting the peptides recoveries. SPE on microelution plates was performed on Waters Positive Pressure‐96 Processor with subsequent evaporation of eluates in nitrogen flow. Though the use of smaller sample volume decreases the pre‐concentration factor and increases the limits of detection of 5 out of 17 detected peptides, the recovery, linearity, and reproducibility of the microelution extraction were comparable with cartridge SPE. The effectiveness of protocols was confirmed by analysis of urine samples containing ipamorelin, and GHRP‐6 and its metabolites. SPE after urine sample dilution with buffer can be used for faster sample preparation. The use of microelution plates decreases consumption of solvents and allows processing of up to 96 samples simultaneously. Cartridge SPE with manual рН adjustment remains the best option for confirmation. Copyright © 2015 John Wiley & Sons, Ltd.     

Detection of stanozolol O‐ and N‐sulfate metabolites and their evaluation as additional markers in doping control

Stanozolol (STAN) is one of the most frequently detected anabolic androgenic steroids in sports drug testing. STAN misuse is commonly detected by monitoring metabolites excreted conjugated with glucuronic acid after enzymatic hydrolysis or using direct detection by liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). It is well known that some of the previously described metabolites are the result of the formation of sulfate conjugates in C17, which are converted to their 17‐epimers in urine. Therefore, sulfation is an important phase II metabolic pathway of STAN that has not been comprehensively studied. The aim of this work was to evaluate the sulfate fraction of STAN metabolism by LC‐MS/MS to establish potential long‐term metabolites valuable for doping control purposes. STAN was administered to six healthy male volunteers involving oral or intramuscular administration and urine samples were collected up to 31 days after administration. Sulfation of the phase I metabolites commercially available as standards was performed in order to obtain MS data useful to develop analytical strategies (neutral loss scan, precursor ion scan and selected reaction monitoring acquisitions modes) to detect potential sulfate metabolites. Eleven sulfate metabolites (M‐I to M‐XI) were detected and characterized by LC‐MS/MS. This paper provides valuable data on the ionization and fragmentation of O‐ sulfates and N‐ sulfates. For STAN, results showed that sulfates do not improve the retrospectivity of the detection compared to the previously described long‐term metabolite (epistanozolol‐N ‐glucuronide). However, sulfate metabolites could be additional markers for the detection of STAN misuse. Copyright © 2016 John Wiley & Sons, Ltd.     

25C‐NBOMe and 25I‐NBOMe metabolite studies in human hepatocytes,in vivo mouse and human urine with high‐resolution mass spectrometry

25C‐NBOMe and 25I‐NBOMe are potent hallucinogenic drugs that recently emerged as new psychoactive substances. To date, a few metabolism studies were conducted for 25I‐NBOMe, whereas 25C‐NBOMe metabolism data are scarce. Therefore, we investigated the metabolic profile of these compounds in human hepatocytes, an in vivo mouse model and authentic human urine samples from forensic cases. Cryopreserved human hepatocytes were incubated for 3 h with 10 μM 25C‐NBOMe and 25I‐NBOMe; samples were analyzed by liquid chromatography high‐resolution mass spectrometry (LC‐HRMS) on an Accucore C18 column with a Thermo QExactive; data analysis was performed with Compound Discoverer software (Thermo Scientific). Mice were administered 1.0 mg drug/kg body weight intraperitoneally, urine was collected for 24 h and analyzed (with or without hydrolysis) by LC‐HRMS on an Acquity HSS T3 column with an Agilent 6550 QTOF; data were analyzed manually and with WebMetabase software (Molecular Discovery). Human urine samples were analyzed similarly. In vitro and in vivo results matched well. 25C‐NBOMe and 25I‐NBOMe were predominantly metabolized by O‐demethylation, followed by O‐di‐demethylation and hydroxylation. All methoxy groups could be demethylated; hydroxylation preferably occurred at the NBOMe ring. Phase I metabolites were extensively conjugated in human urine with glucuronic acid and sulfate. Based on these data and a comparison with synthesized reference standards for potential metabolites, specific and abundant 25C‐NBOMe urine targets are 5’‐desmethyl 25C‐NBOMe, 25C‐NBOMe and 5‐hydroxy 25C‐NBOMe, and for 25I‐NBOMe 2’ and 5’‐desmethyl 25I‐NBOMe and hydroxy 25I‐NBOMe. These data will help clinical and forensic laboratories to develop analytical methods and to interpret results. Copyright © 2016 John Wiley & Sons, Ltd.     

Metabolism study for CUMYL‐4CN‐BINACA in human hepatocytes and authentic urine specimens: Free cyanide is formed during the main metabolic pathway

To further elucidate the metabolism of CUMYL‐4CN‐BINACA, a new synthetic cannabinoid with a cyano group, and to evaluate biomarkers, we incubated the substance in human hepatocytes and analysed 9 authentic urine specimens. We also quantified CUMYL‐4CN‐BINACA and cyanide in blood and provide comprehensive data on the 7 autopsy cases, 5 of them determined CUMYL‐4CN‐BINACA intoxications. For metabolite elucidation, CUMYL‐4CN‐BINACA was incubated with pooled human hepatocytes for up to 5 hours, urine samples were analysed with and without enzymatic hydrolysis. Data was acquired in data‐dependent mode by ultra‐high performance liquid chromatography–high resolution mass spectrometry (UHPLC–HRMS) with an Agilent 6550 QTOF. For quantitative analysis of CUMYL‐4CN‐BINACA, blood samples were precipitated and analysed by liquid chromatography–tandem mass spectrometry (LC–MS/MS). Cyanide was determined by gas chromatography–headspace–nitrogen phosphorus detection (GC–headspace–NPD). CUMYL‐4CN‐BINACA was metabolised via CYP450‐mediated hydroxylation at 4‐butyl position generating a cyanohydrin (M12), which releases free cyanide to form an aldehyde intermediate and eventually generates 4‐hydroxybutyl CUMYL‐BINACA (M11) and CUMYL‐BINACA butanoic acid (M10). Other minor metabolites were produced by hydroxylation, dihydroxylation, N‐dealkylation, and dihydrodiol formation; glucuronidation was observed. One urine sample showed high intensities of M10 and a wide variety of metabolites; the other samples contained fewer metabolites in low abundance and 1 sample showed no metabolites. CUMYL‐4CN‐BINACA blood concentrations ranged from 0.1 to 8.3 ng/g showing an overlap between fatal and non‐fatal concentrations. One blood sample contained 0.36 μg/g cyanide. Release of free cyanide during metabolism is worrying as it might induce liver toxicity. As suggested earlier, CUMYL‐BINACA butanoic acid is the most abundant biomarker in urine, but monitoring of additional metabolites or, even better, analysis for the parent in blood is recommended.     

Use of split‐free nano‐liquid chromatography–mass spectrometry/high resolution mass spectrometry interface to improve the detection of α‐cobratoxin in equine plasma for doping control

Cobra (Naja naja kaouthia) venom contains a toxin called α‐cobratoxin (α‐Cbtx) containing 71 amino acids (MW 7821 Da) with a reported analgesic power greater than morphine. In 2013, the first analytical method for the detection of α‐Cbtx in equine plasma was developed by Bailly‐Chouriberry et al, allowing the confirmation of the presence of α‐Cbtx at low concentrations (1–5 ng/mL or 130–640 fmol/mL) in plasma samples. To increase the method sensitivity and therefore to improve the detection of α‐Cbtx in post‐administration plasma samples, a nano‐liquid chromatography–mass spectrometry/high resolution mass spectrometry (nLC–MS/HRMS) method was developed. This new method allowed us to confirm the presence of α‐Cbtx in plasma samples spiked at 100 pg/mL (12.8 fmol/mL) and the detection of α‐Cbtx was obtained in plasma samples collected 72 hours post‐administration (50 pg/mL or 6.4 fmol/mL) which was defined as the limit of detection (LOD). The presented method is 20‐fold more sensitive compared to the method previously described.     

Determination of a selection of synthetic cannabinoids and metabolites in urine by UHPSFC‐MS/MS and by UHPLC‐MS/MS

Two different analytical techniques, ultra‐high performance supercritical fluid chromatography‐tandem mass spectrometry (UHPSFC‐MS/MS) and reversed phase ultra‐high performance liquid chromatography‐tandem mass spectrometry (UHPLC‐MS/MS), were used for the determination of two synthetic cannabinoids and eleven metabolites in urine; AM‐2201 N‐4‐OH‐pentyl, AM‐2233, JWH‐018 N‐5‐OH‐pentyl, JWH‐018 N‐pentanoic acid, JWH‐073 N‐4‐OH‐butyl, JWH‐073 N‐butanoic acid, JWH‐122 N‐5‐OH‐pentyl, MAM‐2201, MAM‐2201 N‐4‐OH‐pentyl, RCS‐4 N‐5‐OH‐pentyl, UR‐144 degradant N‐pentanoic acid, UR‐144 N‐4‐OH‐pentyl, and UR‐144 N‐pentanoic acid. Sample preparation included a liquid‐liquid extraction after deconjugation with ß‐glucuronidase. The UHPSFC‐MS/MS method used an Acquity UPC^{2 TM} BEH column with a mobile phase consisting of CO₂ and 0.3% ammonia in methanol, while the UHPLC‐MS/MS method used an Acquity UPLC® BEH C₁₈ column with a mobile phase consisting of 5 mM ammonium formate (pH 10.2) and methanol. MS/MS detection was performed with positive electrospray ionization and two multiple reaction monitoring transitions. Deuterated internal standards were used for six of the compounds. Limits of quantification (LOQs) were between 0.04 and 0.4 µg/L. Between‐day relative standard deviations at concentrations ≥ LOQ were ≤20%, with biases within ±19%. Recoveries ranged from 40 to 90%. Corrected matrix effects were within 100 ± 10%, except for MAM‐2201 with UHPSFC‐MS/MS, and for UR‐144 N‐pentanoic acid and MAM‐2201 N‐4‐OH‐pentyl with UHPLC‐MS/MS. Elution order obtained by UHPSFC‐MS/MS was almost opposite to that obtained by UHPLC‐MS/MS, making this instrument setup an interesting combination for screening and confirmation analyses in forensic cases. The UHPLC‐MS/MS method has, since August 2014, been successfully used for confirmation of synthetic cannabinoids in urine samples revealing a positive immunoassay screening result. Copyright © 2015 John Wiley & Sons, Ltd.     

3‐(3,4‐Dihydroxyphenyl)adenine,a urinary DNA adduct formed in mice exposed to high concentrations of benzene

Metabolism of benzene, an important environmental and industrial carcinogen, produces three electrophilic intermediates, namely, benzene oxide and 1,2‐ and 1,4‐benzoquinone, capable of reacting with the DNA. Numerous DNA adducts formed by these metabolites in vitro have been reported in the literature, but only one of them was hitherto identified in vivo. In a search for urinary DNA adducts, specific LC‐ESI‐MS methods have been developed for the determination in urine of six nucleobase adducts, namely, 7‐phenylguanine, 3‐phenyladenine, 3‐hydroxy‐3,N⁴‐benzethenocytosine, N²‐(4‐hydroxyphenyl)guanine, 7‐(3,4‐dihydroxyphenyl)guanine and 3‐(3,4‐dihydroxyphenyl)‐adenine (DHPA), with detection limits of 200, 10, 260, 50, 400 and 200 pg ml^?1, respectively. Mice were exposed to benzene vapors at concentrations of 900 and 1800 mg m^?3, 6 h per day for 15 consecutive days. The only adduct detected in their urine was DHPA. It was found in eight out of 30 urine samples from the high‐exposure group at concentrations of 352 ± 146 pg ml^?1 (mean ± SD; n = 8), whereas urines from the low‐exposure group were negative. Assuming the DHPA concentration in the negative samples to be half of the detection limit, conversion of benzene to DHPA was estimated to 2.2 × 10^?6% of the absorbed dose. Thus, despite the known high mutagenic and carcinogenic potential of benzene, only traces of a single DNA adduct in urine were detected. In conclusion, DHPA is an easily depurinating adduct, thus allowing indication of only high recent exposure to benzene, but not long‐term damage to DNA in tissues. Copyright © 2012 John Wiley & Sons, Ltd.     

Metabolic profiling of synthetic cannabinoid 5F‐ADB by human liver microsome incubations and urine samples using high‐resolution mass spectrometry

5F‐ADB (methyl 2‐{[1‐(5‐fluoropentyl)‐1H‐indazole‐3‐carbonyl] amino}‐3,3‐dimethylbutanoate) is a frequently abused new synthetic cannabinoid that has been sold since at least the end of 2014 on the drug market and has been classified as an illicit drug in most European countries, as well as Turkey, Japan, and the United States. In this study, the in vitro metabolism of 5F‐ADB was investigated by using pooled human liver microsomes (HLMs) assay and liquid chromatography‐high‐resolution mass spectrometry (LC–HRMS). 5F‐ADB (5 μmol/L) was incubated with HLMs for up to 3 hours, and the metabolites were identified using LC–HRMS and software‐assisted data mining. The in vivo metabolism was investigated by the analysis of 30 authentic urine samples and was compared to the data received from the in vitro metabolism study. Less than 3.3% of the 5F‐ADB parent compound remained after 1 hour of incubation, and no parent drug was detected after 3 hours. We identified 20 metabolites formed via ester hydrolysis, N‐dealkylation, oxidative defluorination, hydroxylation, dehydrogenation, further oxidation to N‐pentanoic acid and glucuronidation or a combination of these reactions in vitro. In 12 urine samples (n = 30), 5F‐ADB was detected as the parent drug. Three of the identified main metabolites 5F‐ADB carboxylic acid (M20), monohydroxypentyl‐5F‐ADB (M17), and carboxypentyl ADB carboxylic acid (M8) were suggested as suitable urinary markers. The screening of 8235 authentic urine samples for identified 5F‐ADB metabolites in vitro resulted in 3135 cases of confirmed 5F‐ADB consumption (38%).