Issues pertaining to the analysis of buprenorphine and its metabolites by gas chromatography–mass spectrometry

“Substitution therapy” and the use of buprenorphine (B) as an agent for treating heroin addiction continue to gain acceptance and have recently been implemented in Taiwan. Mature and widely utilized gas chromatography–mass spectrometry (GC–MS) technology can complement the low cost and highly sensitive immunoassay (IA) approach to facilitate the implementation of analytical tasks supporting compliance monitoring and pharmacokinetic/pharmacogenetic studies. Issues critical to GC–MS analysis of B and norbuprenorphine (NB) (free and as glucuronides), including extraction, hydrolysis, derivatization, and quantitation approaches were studied, followed by comparing the resulting data against those derived from IA and two types of liquid chromatography–tandem mass spectrometry (LC–MS/MS) methods. Commercial solid-phase extraction devices, highly effective for recovering all metabolites, may not be suitable for the analysis of free B and NB; acetyl-derivatization products exhibit the most favorable chromatographic, ion intensity, and cross-contribution characteristics for GC–MS analysis. Evaluation of IA, GC–MS, and LC–MS/MS data obtained in three laboratories has proven the 2-aliquot GC–MS protocol effective for the determination of free B and NB and their glucuronides.     

Effects of propyphenazone and other non-steroidal anti-inflammatory agents on the synthetic and endogenous androgenic anabolic steroids urinary excretion and/or instrumental detection

This paper describes the effects of oral administration of non-steroidal anti-inflammatory drugs on the endogenous and synthetic anabolic androgenic steroids urinary excretion as assessed by gas-chromatography mass-spectrometry. Experiments were carried out on 5 male subjects, with pathologies and/or diseases, treated with non-steroidal anti-inflammatory drugs. To set up the individual baseline variability of testosterone and its main metabolites, urine samples were collected for 3 days, every 2 h prior to the administration of the drug(s); whereas the study of the effects of a single dose of each drug, here considered, on the endogenous androgen steroid urinary concentrations, was assessed by collecting urine samples for 2 days, every 2 h. Data obtained after drugs administration were then evaluated taking into account the individual baseline variability. The results showed that, only in the case of propyphenazone administration, the relative urinary concentrations of some testosterone metabolites were significantly altered. More specifically, the urinary levels of dehydroepiandrosterone, 11keto-etiocholanolone, 11β-hydroxyandrosterone, 11β-hydroxyetiocholanolone, androsterone, etiocholanolone and some metabolite ratios decrease significantly, generally between 2 and 10 h after administration of the drug, whereas no effects were observed on urinary calculated concentrations of testosterone, epitestosterone, 5α-androstane-3α,17β-diol, 5β-androstane-3α,17β-diol and testosterone/epitestosterone ratio. The observed effects do not depend on alterations on pharmacokinetics (excretion/metabolism), but on steroid sample preparation steps (hydrolysis and derivatization) inhibition. More specifically the significant decrease of dehydroepiandrosterone and testosterone metabolites urinary levels was due to a reduced yield of the steroid derivatization step for the presence in urine of the main metabolites of propyphenazone, namely hydroxyl-propyphenazone metabolites.     

A new reliable sample preparation for high throughput focused steroid profiling by gas chromatography–mass spectrometry

The use of steroid hormones as growth promoters in cattle has been banned within the European Union since 1988 but can still be fraudulently employed in animal breeding farms for anabolic purposes. If an efficient monitoring of synthetic compounds (screening and confirmation) is ensured today by many laboratories, pointing out suspicious samples from a natural steroids abuse remains a tricky challenge due to the difficulty to set relevant threshold levels for these endogenous compounds. The development of focused profiling or untargeted metabolomic approaches is then emerging in this context, with the objective to reveal potential biomarkers signing an exogenous administration of such natural steroids. This study aimed to assess sample preparation procedures based on microextraction and adapt them to high throughput urinary profiling or metabolomic analyses based on gas chromatography–mass spectrometry measurement. Two techniques have been tested and optimised, namely solid phase microextraction (SPME) and microextraction by packed sorbent (MEPS), using five model steroid metabolites (16α-hydroxyandrosterone, 2α-hydroxytestosterone, 11-keto,5β-androstanedione, 6α-hydroxyestradiol and 7β-hydroxypregnenolone). The considered performance criteria included not only the absolute response of the targeted compounds but also the robustness of the materials, and the global aspect of the diagnostic ion chromatograms obtained. After only five successive urinary extractions, a clear degradation of the SPME fiber was observed which led to discard this method as a relevant technique for profiling, whereas no degradation was observed on MEPS sorbent. Repeatability and recovery yields were calculated from urine samples fortified at 500 μg L⁻¹ and extracted by MEPS. They were found respectively below 11% and above 60% for all model compounds. Detection limits were in the 5–15 μg L⁻¹ range depending on the compounds, and a good linearity was observed on the 10–75 μg L⁻¹ range (R² > 0.99). This methodology was applied on urine samples collected from control versus androstenedione-treated bovines, revealing a significant concentration increase for several well-known metabolites such as etiocholanolone, 5α-androstane-3β,17α-diol, 5β-androstane-3α,17α-diol and 5-androstene-3β,17α-diol. Finally, these results allowed to confirm the suitability of the developed strategy and give to this new MEPS application a promising interest in the field of GC–MS based steroid profiling and metabolomic.     

A single step solid-phase extraction method for complete separation of sterol oxidation products in food lipids

One of the crucial steps in determination of sterol oxidation products (SOPs) in foods is their enrichment and purifications by various preparative methods for further analysis by GC and GC–MS. Among the preparative methods, SPE of various adsorbents and solvent systems, are being used most widely. At present, no single step SPE method is suitable to completely separate the SOPs. In this study, a SPE (1 g silica) method, suitable for both transesterified and cold saponified oil samples, was developed to separate completely SOPs from other lipid components. This method resulted in high recovery from rapeseed oil of added 5β,6β-epoxycholestan-3β-ol (94-96%), cholest-5-en-3β-ol-7-one(94%), cholestane-3β,5α,6β-triol (88–91%), cholest-5-en-3β,7α-diol and 5α,6α-epoxycholestan-3β-ol (88–90%). The method has a high sample capacity of up to 1 g transesterified or cold-saponified oil sample. The method was tested and applied to different vegetable oils and to monitor the effects of refining processes on POPs in hazelnut oil.     

Exploring metabolic syndrome serum profiling based on gas chromatography mass spectrometry and random forest models

Metabolic syndrome (MetS) is a constellation of the most dangerous heart attack risk factors: diabetes and raised fasting plasma glucose, abdominal obesity, high cholesterol and high blood pressure. Analysis and representation of the variances of metabolic profiles is urgently needed for early diagnosis and treatment of MetS. In current study, we proposed a metabolomics approach for analyzing MetS based on GC–MS profiling and random forest models. The serum samples from healthy controls and MetS patients were characterized by GC–MS. Then, random forest (RF) models were used to visually discriminate the serum changes in MetS based on these GC–MS profiles. Simultaneously, some informative metabolites or potential biomarkers were successfully discovered by means of variable importance ranking in random forest models. The metabolites such as 2-hydroxybutyric acid, inositol and d-glucose, were defined as potential biomarkers to diagnose the MetS. These results obtained by proposed method showed that the combining GC–MS profiling with random forest models was a useful approach to analyze metabolites variances and further screen the potential biomarkers for MetS diagnosis.     

Liquid chromatography–tandem quadrupole mass spectrometry and comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry measurement of targeted metabolites of Methylobacterium extorquens AM1 grown on two different carbon sources

Complementary methods using liquid chromatography–tandem quadrupole mass spectrometry (LC–MS/MS) and comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOF-MS) were developed and applied to determine targeted metabolites involved in central carbon metabolism [including tricarboxylic acid cycle, serine cycle, ethylmalonyl-coenzyme A (ethylmalonyl-CoA) pathway and poly-β-hydroxybutyrate cycle] of the bacterium Methylobacterium extorquens AM1 grown on two carbon sources, ethylamine (C2) and succinate (C4). Nucleotides, acyl-CoAs and a few volatile metabolites in cell extracts of M. extorquens AM1 were readily separated using either hydrophilic interaction liquid chromatography or reversed-phase liquid chromatography, and detected with good sensitivity by MS/MS. However, volatile intermediates within a low mass range (<300 m/z), especially at low abundance (such as glyoxylic acid and others <500 nM), were more effectively analyzed by GC × GC–TOF-MS which often provided better sensitivity, resolution and reproducibility. The complementary nature of the LC-based and GC-based methods allowed the comparison of 39 metabolite concentrations (the lowest level was at 139.3 nM). The overlap between the LC-based and GC-based methods of seven metabolites provided a basis to check for consistency between the two methods, and thus provided some validation of the quantification accuracy. The abundance change of 20 intermediates further suggested differences in pathways linked to C2 and C4 metabolism.     

Development of GC–MS/MS method with programmable temperature vaporization large volume injection for monitoring of 17β-estradiol and 2-methoxyestradiol in plasma

Monitoring of estradiol and its metabolites in biological samples is essential for the accurate diagnosis of a number of endocrine diseases. In this study, a sensitive, precise and specific GC–MS/MS method for the quantification of 17β-estradiol (17-BE) and its main metabolite, 2-methoxyestradiol (2-MEOE), in plasma was developed and validated. Plasma concentrations of these steroids are currently investigated as diagnostic markers for pre-eclampsia, a systematic disorder of pregnancy and a leading cause of maternal and fetal morbidity and mortality worldwide.     

Comparison of sulfo‐conjugated and gluco‐conjugated urinary metabolites for detection of methenolone misuse in doping control by LC‐HRMS,GC‐MS and GC‐HRMS

Methenolone (17β‐hydroxy‐1‐methyl‐5α‐androst‐1‐en‐3‐one) misuse in doping control is commonly detected by monitoring the parent molecule and its metabolite (1‐methylene‐5α‐androstan‐3α‐ol‐17‐one) excreted conjugated with glucuronic acid using gas chromatography‐mass spectrometry (GC‐MS) and liquid chromatography mass spectrometry (LC‐MS) for the parent molecule, after hydrolysis with β‐glucuronidase. The aim of the present study was the evaluation of the sulfate fraction of methenolone metabolism by LC‐high resolution (HR)MS and the estimation of the long‐term detectability of its sulfate metabolites analyzed by liquid chromatography tandem mass spectrometry (LC‐HRMSMS) compared with the current practice for the detection of methenolone misuse used by the anti‐doping laboratories. Methenolone was administered to two healthy male volunteers, and urine samples were collected up to 12 and 26 days, respectively. Ethyl acetate extraction at weak alkaline pH was performed and then the sulfate conjugates were analyzed by LC‐HRMS using electrospray ionization in negative mode searching for [M‐H]^? ions corresponding to potential sulfate structures (comprising structure alterations such as hydroxylations, oxidations, reductions and combinations of them). Eight sulfate metabolites were finally detected, but four of them were considered important as the most abundant and long term detectable. LC clean up followed by solvolysis and GC/MS analysis of trimethylsilylated (TMS) derivatives reveal that the sulfate analogs of methenolone as well as of 1‐methylene‐5α‐androstan‐3α‐ol‐17‐one, 3z‐hydroxy‐1β‐methyl‐5α‐androstan‐17‐one and 16β‐hydroxy‐1‐methyl‐5α‐androst‐1‐ene‐3,17‐dione were the major metabolites in the sulfate fraction. The results of the present study also document for the first time the methenolone sulfate as well as the 3z‐hydroxy‐1β‐methyl‐5α‐androstan‐17‐one sulfate as metabolites of methenolone in human urine. The time window for the detectability of methenolone sulfate metabolites by LC‐HRMS is comparable with that of their hydrolyzed glucuronide analogs analyzed by GC‐MS. The results of the study demonstrate the importance of sulfation as a phase II metabolic pathway for methenolone metabolism, proposing four metabolites as significant components of the sulfate fraction. Copyright © 2015 John Wiley & Sons, Ltd.     

Analytical performance of a triple quadrupole mass spectrometer compared to a high resolution mass spectrometer for the analysis of polybrominated diphenyl ethers in fish

Polybrominated diphenyl ethers (PBDEs) are a class of flame retardants used globally in many consumer products and industrial applications. Traditionally, gas chromatography–high resolution mass spectrometry (GC–HR-MS) is the method of choice for analysis of PBDEs in environmental samples because it offers high sensitivity and selectivity, resulting in less interferences. However, the specificity offered by gas chromatography-triple quadrupole tandem mass spectrometry (GC–QQQ-MS/MS), operated in selected reaction monitoring mode, provides a more affordable alternative to GC–HR-MS for the analysis of PBDEs in complex environmental samples. In this study, an analytical method was developed for the analysis of 41 PBDE congeners in fish using GC–QQQ-MS/MS. Results from the analysis of three fish species [lake trout (Salvelinus namaycush), yellow perch (Perca flavescens), and round goby (Neogobius melanostomus)] using GC–QQQ-MS/MS were compared with those obtained by GC–HR-MS. These species were selected because they represent varying levels of lipid-rich matrix and contaminant loads. Instrumental limits of detection for the GC–QQQ-MS/MS ranged from 0.04 pg to 41 pg, whereas those for the GC–HR-MS ranged from 5 pg to 85 pg. The PBDE values obtained from these two methods were highly correlated, R² values >0.7, for all three fish species, supporting the suitability of GC–QQQ-MS/MS for analysis of PBDEs in fish with varying fat content.     

Feasibility of ultra-high performance liquid and gas chromatography coupled to mass spectrometry for accurate determination of primary and secondary phthalate metabolites in urine samples

Phthalates (PAEs) are ubiquitous toxic chemical compounds. During the last few years, some phthalate metabolites (MPAEs) have been proposed as appropriate biomarkers in human urine samples to determine PAE human intake and exposure. So, it is necessary to have fast, easy, robust and validated analytical methods to determine selected MPAEs in urine human samples. Two different instrumental methods based on gas (GC) and ultra-high performance liquid (UHPLC) chromatography coupled to mass spectrometry (MS) have been optimized, characterized and validated for the simultaneous determination of nine primary and secondary phthalate metabolites in urine samples. Both instrumental methods have similar sensitivity (detection limits ranged from 0.03 to 8.89 pg μL⁻¹ and from 0.06 to 0.49 pg μL⁻¹ in GC–MS and UHPLC–MS², respectively), precision (repeatability, expressed as relative standard deviation, which was lower than 8.4% in both systems, except for 5OH-MEHP in the case of GC–MS) and accuracy. But some advantages of the UHPLC–MS² method, such as more selectivity and lower time in the chromatographic runs (6.8 min vs. 28.5 min), have caused the UHPLC–MS² method to be chosen to analyze the twenty one human urine samples from the general Spanish population. Regarding these samples, MEP showed the highest median concentration (68.6 μg L⁻¹), followed by MiBP (23.3 μg L⁻¹), 5cx-MEPP (22.5 μg L⁻¹) and MBP (19.3 μg L⁻¹). MMP (6.99 μg L⁻¹), 5oxo-MEHP (6.15 μg L⁻¹), 5OH-MEHP (5.30 μg L⁻¹) and MEHP (4.40 μg L⁻¹) showed intermediate levels. Finally, the lowest levels were found for MBzP (2.55 μg L⁻¹). These data are within the same order of magnitude as those found in other similar populations.     

Ultra high performance supercritical fluid chromatography coupled with tandem mass spectrometry for screening of doping agents. II: Analysis of biological samples

The potential and applicability of UHPSFC–MS/MS for anti-doping screening in urine samples were tested for the first time. For this purpose, a group of 110 doping agents with diverse physicochemical properties was analyzed using two separation techniques, namely UHPLC–MS/MS and UHPSFC–MS/MS in both ESI+ and ESI− modes. The two approaches were compared in terms of selectivity, sensitivity, linearity and matrix effects. As expected, very diverse retentions and selectivities were obtained in UHPLC and UHPSFC, proving a good complementarity of these analytical strategies. In both conditions, acceptable peak shapes and MS detection capabilities were obtained within 7 min analysis time, enabling the application of these two methods for screening purposes. Method sensitivity was found comparable for 46% of tested compounds, while higher sensitivity was observed for 21% of tested compounds in UHPLC–MS/MS and for 32% in UHPSFC–MS/MS. The latter demonstrated a lower susceptibility to matrix effects, which were mostly observed as signal suppression. In the case of UHPLC–MS/MS, more serious matrix effects were observed, leading typically to signal enhancement and the matrix effect was also concentration dependent, i.e., more significant matrix effects occurred at the lowest concentrations.     

A fast method for the identification of Mycobacterium tuberculosis in sputum and cultures based on thermally assisted hydrolysis and methylation followed by gas chromatography–mass spectrometry

A fast gas chromatography–mass spectrometry (GC–MS) method with minimum sample preparation is described for early diagnosis of tuberculosis (TB). The automated procedure is based on the injection of sputum samples which are then methylated inside the GC injector using thermally assisted hydrolysis and methylation (THM). The THM–GC–MS procedure was optimized for the injection of sputum samples. For the identification of Mycobacterium tuberculosis the known marker tuberculostearic acid (TBSA) and other potential markers were evaluated. Hexacosanoic acid in combination with TBSA was found to be specific for the presence of M. tuberculosis. For validation of the method several sputum samples with different viscosities spiked with bacterial cultures were analyzed. Finally, 18 stored sputum samples collected in Vietnam from patients suspected to suffer from TB were re-analyzed in Amsterdam by microscopy after decontamination/concentration and using the new THM–GC–MS method. No false positives were found by THM–GC–MS and all patients who were diagnosed with TB were also found positive using our newly developed THM–GC–MS method. These results show that the new fast and sensitive THM–GC–MS method holds great potential for the diagnosis of TB.     

A systematic investigation to optimize simultaneous extraction and liquid chromatography tandem mass spectrometry analysis of estrogens and their conjugated metabolites in milk

In this study, the simultaneous extraction of estrone (E1), 17β-estradiol (E2), estriol (E3), ethinylestradiol (EE2), and their glucuronated and sulfated metabolites in milk was optimized using solid-phase extraction (SPE). The aim of this research was to analyze estrogens and their conjugated metabolites by liquid chromatography with tandem mass spectrometry (LC–MS/MS) in a single run, without the need to perform enzymatic cleavage and derivatization. Two SPE cartridges in tandem were used, consisting of sorbents based on the hydrophilic–lipophilic balance and amine-functionalized packing materials. To monitor analyte loss at every step of the SPE procedure ¹⁴C-labeled E2 was spiked into the milk sample and the radioactivity was monitored at all stages of the SPE. In addition, non-radiolabeled standards of estrogens and metabolites were used to optimize solvent systems for the SPE and LC–MS/MS. The optimized method described in this paper can achieve recoveries ranging from 72% to 117% for the free estrogens (E1, E2, E3, and EE2), and 62% to 112% for seven conjugated metabolites. The three doubly conjugated, highly polar metabolites included in this study gave lower recoveries (≤43%) due to poor retention in SPE. Finally, commercial milk samples were analyzed for the presence of estrogens and their conjugated metabolites. Estrone (concentration range: 23–67 ng/L) was found to be the major free estrogen present in all milk samples. Estradiol was consistently observed in milk, but the concentrations were below the limit of detection (LOD of 10 ng/L), and no estriol and ethinylestradiol were detected. Several conjugated estrogen metabolites were identified, 17β-estradiol-3-glucuronide (71–289 ng/L), estrone-3-sulfate (60–240 ng/L), 17β-estradiol-3,17β-sulfate (<LOD to 30 ng/L), and estrone-3-glucuronide (<LOQ of 25 ng/L). This method proved efficient in the simultaneous analysis of estrogens and their metabolites in milk.     

Sensitive monitoring of monoterpene metabolites in human urine using two-step derivatisation and positive chemical ionisation-tandem mass spectrometry

A gas chromatographic–positive chemical ionisation-tandem mass spectrometric (GC–PCI-MS/MS) method for the simultaneous determination of 10 oxidative metabolites of the monoterpenoid hydrocarbons α-pinene, (R)-limonene, and Δ³-carene ((+)-3-carene) in human urine was developed and tested for the monoterpene biomonitoring of the general population (n = 36). The method involves enzymatic cleavage of the glucuronides followed by solid-supported liquid–liquid extraction and derivatisation using a two-step reaction with N,O-bis(trimethylsilyl)-trifluoroacetamide and N-(trimethylsilyl)imidazole. The method proved to be both sensitive and reliable with detection limits ranging from 0.1 to 0.3 μg L⁻¹. In contrast to the frequent and distinct quantities of (1S,2S,4R)-limonene-1,2-diol, the (1R,2R,4R)-stereoisomer could not be detected. The expected metabolite of (+)-3-carene, 3-caren-10-ol was not detected in any of the samples. All other metabolites were detected in almost all urine samples.     

Morphine-induced conditioned place preference in mice: Metabolomic profiling of brain tissue to find “molecular switch” of drug abuse by gas chromatography/mass spectrometry

Conditioned place preference (CPP) is a widely used model to explore the mechanism of context-dependent learning. In this work, we developed a GC–MS method to investigate the metabolites in mice brain which was used to study the mechanism of context-dependent learning associated with rewarding effect of morphine. Metabolites were extracted from brain tissues and derivatized followed by analysis by gas chromatography/mass spectrometry (GC–MS). In total, 69 peaks were identified as known compounds. By a Wilcoxon ran sum test with p value ≤0.05, 21 metabolites were selected and considered as the potential biomarkers of morphine in mice brain. Using principal component analysis (PCA) and receiver-operator characteristic (ROC) curves, a model was constructed with a combination of these 21 metabolic markers. Multivariate statistics of the model yielded separation between the two groups with an area under the curve value of 0.947. Some metabolites were further discussed in detail about their pathway. Results showed that our technique can be successfully applied to profile for biomarkers and in understanding molecular mechanisms of drug abuse.     

Optimisation of a headspace-solid-phase micro-extraction method for simultaneous determination of organometallic compounds of mercury,lead and tin in water by gas chromatography–tandem mass spectrometry

In this work, a headspace-solid-phase micro-extraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC–MS) method for multielemental speciation of organometallic compounds of mercury, lead and tin in water samples was upgraded by the introduction of tandem mass spectrometry (MS/MS) as detection technique. The analytical method is based on the ethylation with NaBEt₄ and simultaneous headspace-solid-phase micro-extraction of the derivative compounds followed by GC–MS/MS analysis. The main experimental parameters influencing the extraction efficiency such as derivatisation time, extraction time and extraction temperature were optimized. The overall optimum extraction conditions were the following: a 50 μm/30 μm divinyl-benzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) SPME fibre, 150 min derivatisation time, 15 min extraction time, sample agitation at 250 rpm and 40 °C extraction temperature. The analytical characteristics of the HS-SPME method combined with GC–MS and GC–MS/MS were evaluated. The combination of both techniques HS-SPME and GC–MS/MS allowed to attain lower limits of detection (4–33 ng l⁻¹) than those obtained by HS-SPME–GC–MS (17–45 ng l⁻¹). The proposed method presented good linear regression coefficients (r² > 0.9970) and repeatability (4.8–21.0%) for all the compounds under study. The accuracy of the method measured as the average percentage recovery of the compounds in spiked river water and seawater samples was higher than 80% for all the compounds studied, except for monobutyltin in the river water sample. A study of the uncertainty associated with the analytical results was also carried out.     

Direct rapid analysis of multiple PPCPs in municipal wastewater using ultrahigh performance liquid chromatography–tandem mass spectrometry without SPE pre-concentration

Ultrahigh performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) was utilized to develop a rapid, sensitive and reliable method without solid phase extraction (SPE) pre-concentration for trace analysis of 11 pharmaceuticals and personal care products (PPCPs) in in?uent and ef?uent from municipal wastewater treatment plants (WWTPs). This method not only shortened the analysis time but also reduced analysis cost significantly by omitting SPE process and avoiding the consumption of SPE cartridge. Detection parameters for UHPLC–MS/MS analysis were optimized, including sample pH, eluent, mobile phase (solvent and additive), column temperature, and ?ow rate. Under the optimal conditions, all analytes were well separated and detected within 8.0 min by UHPLC–MS/MS. The method quantification limits (MQLs) for the 11 PPCPs ranged from 0.040 to 88 ng L⁻¹ and from 0.030 to 90 ng L⁻¹ for influent and effluent, respectively. The matrix effect was systematically investigated and quantified for different types of samples. The analysis of in?uent and ef?uent samples of two WWTPs in Hong Kong revealed the presence of 11 PPCPs, including acyclovir, benzophenone-3, benzylparaben, carbamazepine, ethylparaben, fluconazole, fluoxetine, methylparaben, metronidazole, propylparaben, and ranitidine. Their concentrations ranged from 9.1 to 1810 ng L⁻¹ in influent and from 6.5 to 823 ng L⁻¹ in effluent samples collected from Hong Kong WWTPs.     

Analytical challenges in doping control: Comprehensive two-dimensional gas chromatography with time of flight mass spectrometry,a promising option

Doping control screening based on the enhanced resolution of comprehensive two-dimensional (2D) gas chromatography hyphenated to time of flight mass spectrometer was investigated. The identification of anabolic agents (clenbuterol, norandrosterone, epimetendiol, two methyltestosterone metabolites and 3′-hydroxystanozolol) contained in a spiked urine sample (2 ng/ml) was demonstrated. Special emphasis was given to 3′-hydroxystanozolol, mainly considering the difficulty in its detection. In contrast to conventional GC–MS approaches that must use single-ion monitoring, the GC × GC–TOFMS method enabled the identification of that metabolite through the deconvolution of the full mass spectrum and also resolved the co-eluted peaks of 3′-hydroxystanozolol and an endogenous component.     

Aromatic amines from polyurethane adhesives in food packaging: The challenge of identification and pattern recognition using Quadrupole-Time of Flight-Mass Spectrometry

Toxic primary aromatic amines (PAAs) are reaction products from residual isocyanates in polyurethane adhesives. The maximum migration level of the total sum of PAAs is 10 ng g⁻¹ of food. This paper reports on a method for quantification of 18 PAAs by UHPLC–MS/MS that was optimised and applied to a series of industrial laminates prepared from polyurethane adhesives. Non-intentionally added substances (NIAS), impurities and other migrants were identified by Q-TOF/MS^E. A comparison of the quantitative values obtained by the colorimetric method using NEDA and by UHPLC–MS/MS confirmed that the first method can overestimate the quantification of PAAs. This could be attributed to the impurities and other NIAS present in the plastic laminate. Values of R² in the analytical characteristics of UHPLC–MS/MS were obtained, the best value being 0.9964 and the most unfavourable 0.7626. The detection limit (LOD) and the quantification limit (LOQ) were 2 pg g⁻¹ and 7 pg g⁻¹, respectively. The stability of the PAAs over time in the acidic simulant in contact with the plastic laminate is also reported.     

Development of a liquid–chromatography tandem mass spectrometry and ultra-high-performance liquid chromatography high-resolution mass spectrometry method for the quantitative determination of zearalenone and its major metabolites in chicken and pig plasma

A sensitive and specific method for the quantitative determination of zearalenone (ZEN) and its major metabolites (α-zearalenol (α-ZEL), β-zearalenol (β-ZEL), α-zearalanol (α-ZAL), β-zearalanol (β-ZAL) and zearalanone (ZAN)) in animal plasma using liquid chromatography combined with heated electrospray ionization (h-ESI) tandem mass spectrometry (LC–MS/MS) and high-resolution Orbitrap^® mass spectrometry ((U)HPLC–HR–MS) is presented. The sample preparation was straightforward, and consisted of a deproteinization step using acetonitrile. Chromatography was performed on a Hypersil Gold column (50 mm × 2.1 mm i.d., dp: 1.9 μm, run-time: 10 min) using 0.01% acetic acid in water (A) and acetonitrile (B) as mobile phases.