Quantification of organic acids in particulate matter by coupling of thermally assisted hydrolysis and methylation with thermodesorption-gas chromatography–mass spectrometry

A quantitative method for the determination of organic acids in atmospheric particles is developed. The method couples a derivatisation step (thermally assisted hydrolysis and methylation) and a Curie point pyrolyser as a thermal desorption technique and gas chromatography–mass spectrometry (CPP-GC–MS). Among the reagents tested (tetramethylammonium hydroxide (TMAH), tetramethylammonium acetate (TMAAc) and phenyltrimethylammonium hydroxide (TMPAH)), the best performance was found using TMAAc as a derivatisation reagent for the reaction time of 4 s at 510 °C as heating temperature. Calibration was performed for a series of fatty acids (FA), dicarboxylic acids (DCA) and terpenoic acids (TA) under these conditions. Coefficients of determination (R²) were between 0.94 and 0.98. Limits of detection (LOD) were in the nanogram-range between 0.1 and 3.6 ng. The method is applied on atmospheric particle samples to obtain the quantification reproducibility and quantification limits. Reproducibility was determined in terms of relative standard deviations (RSD) for ambient aerosol samples collected by a high-volume-sampler (HVS, RSD = 6–45%, n = 10) and a Berner impactor (BI, RSD = 5–34%, n = 10). Based on 24 h sampling time the developed method enables quantification of all three classes of acids for both sampling techniques. Calibration data and presented volume concentrations are compared with literature data. A comparison with an off-line methylation-GC–MS using BF₃ as a derivatisation reagent and capillary electrophoresis coupled mass spectrometry (CE-MS) showed a good agreement. Minimal sample preparation is the main advantage of the developed method. Depending on the sensitivity requirements the present method can be a fast and simple alternative to GC–MS techniques with conventional sample preparation steps for semi-volatile organic acids.     

A method based on microextraction by packed sorbent-programmed temperature vaporizer–fast gas chromatography–mass spectrometry for the determination of aromatic amines in environmental water samples

We report a sensitive method for the determination of 15 aromatic amines in environmental water samples. They have been included in the list of priority pollutants in surface water by the European Union. The method is based on analyte enrichment using microextraction by packed sorbent (MEPS) and later analysis using programmed temperature vaporizer-gas chromatography-mass spectrometry (PTV-GC-MS). All MEPS steps were carried out manually. The detection limits were of the order of nanograms per liter for most of the compounds. The results were compared with those obtained without MEPS using the method exclusively based on direct injection of the sample into the PTV-GC-MS. External calibration in ultrapure water was used in the determination of the compounds studied in five types of water samples (sea, river, tap, influent, and effluent waste water) since no significant matrix effect was found. The results obtained can be considered highly satisfactory and they revealed the presence of aniline in the sea and the influent and effluent waste water samples.     

Multi-residue method for the determination of organochlorine pesticides in fish feed based on a cleanup approach followed by gas chromatography–triple quadrupole tandem mass spectrometry

A multi-residue method for the determination of organochlorine pesticides in fish feed samples was developed and optimized. The method is based on a cleanup step of the extracted fat, carried out by liquid–liquid extraction on diatomaceous earth cartridge with n-hexane/acetonitrile (80/20, v/v) followed by solid phase extraction (SPE) with silica gel–SCX cartridge, before the identification and quantification of the residues by gas chromatography–triple quadrupole tandem spectrometry (GC–MS/MS). Performance characteristics, such as accuracy, precision, linear range, limits of detection (LOD) and quantification (LOQ), for each pesticide were determined. Instrumental LODs ranged from 0.01 to 0.11 μg L⁻¹, LOQs were in the range of 0.02–0.35 μg L⁻¹, and calibration curves were linear (r² > 0.999) in the whole range of explored concentrations (5–100 μg L⁻¹). Repeatability values were in the range of 3–15%, evaluated from the relative standard deviation of six samples spiked at 100 μg kg⁻¹ of fat, and in compliance with that derived by the Horwitz's equation. No matrix effects or interfering substances were observed in fish feed analyses. The proposed method allowed high recoveries (92–116%) of spiked extracted fat samples at 100 μg kg⁻¹, and very low LODs (between 0.02 and 0.63 μg kg⁻¹) and LOQs (between 0.05 and 2.09 μg kg⁻¹) determined in fish feed samples.     

Determination of amino acids in selenium-enriched yeast by gas chromatography–mass spectrometry after microwave assisted hydrolysis

A simple, rapid microwave digestion procedure for protein hydrolysis preceding the determination of amino acids in yeast using gas chromatography–mass spectrometry (GC–MS) is described. Protein hydrolysis was performed in a focused microwave using 4 M methanesulfonic acid (MAS). Amino acids were derivatized with methyl chlorofomate (MCF) and extracted into chloroform prior to GC–MS analysis. The microwave parameters, including power, temperature and heating time, were optimized. It was found that temperature and heating time were the most influential factors. A total of 17 amino acids were determined in selenium-enriched yeast with use of standard addition calibration. Limits of detection and quantitation (LODs/LOQs) of the amino acids measured were in the sub-nmol range, suitable for monitoring of amino acids in yeast and other food products.     

Complementary fragmentation pattern analysis by gas chromatography–mass spectrometry and liquid chromatography tandem mass spectrometry confirmed the precious lignan content of Cirsium weeds

In this paper, as novelties to the field, it is confirmed at first, that the fruits of Cirsium species, regarded as injurious weeds, do contain lignans, two, different butyrolactone-type glycoside/aglycone pairs: the well known arctiin/arctigenin and the particularly rare tracheloside/trachelogenin species. These experiences were supported by gas chromatography–mass spectrometry (GC–MS), by liquid chromatography tandem mass spectrometry (LC–MS/(MS)) and by nuclear magnetic resonance (NMR) spectroscopy. The study reflects the powerful impact of the complementary chromatographic mass fragmentation evidences resulting in the identification and quantification, the extremely rare, with on line technique not yet identified and described, tracheloside/trachelogenin pair lignans, without authentic standard compounds. Fragmentation pattern analysis of the trimethylsilyl (TMS) derivative of trachelogenin, based on GC–MS, via two different fragmentation pathways confirmed the detailed structure of the trachelogenin molecule. The complementary chromatographic evidences have been unambiguously confirmed, by ¹H and ¹³C NMR analysis of trachelogenin, isolated by preparative chromatography. Identification and quantification of the fruit extracts of four Cirsium (C.) species (C. arvense, C. canum, C. oleraceum, and C. palustre), revealed that (i) all four species do accumulate the tracheloside/trachelogenin or the arctiin/arctigenin butyrolactone-type glycoside/aglycone pairs, (ii) the overwhelming part of lignans are present as glycosides (tracheloside 9.1–14.5 mg/g, arctiin 28.6–39.3 mg/g, expressed on dry fruit basis), (iii) their acidic and enzymatic hydrolyses to the corresponding aglycones, to trachelogenin and arctigenin are fast and quantitative and (iv) the many-sided beneficial trachelogenin and arctigenin can be prepared separately, without impurities, excellent for medicinal purposes.     

One-step extraction and derivatization liquid-phase microextraction for the determination of chlorophenols by gas chromatography–mass spectrometry

A sample pretreatment method for the determination of 18 chlorophenols (CPs) in aqueous samples by derivatization liquid-phase microextraction (LPME) was investigated using gas chromatography–mass spectrometry. Derivatization reagent was spiked into the extraction solvent to combine derivatization and extraction into one step. High sensitivity of 18 CPs derivatives could be achieved after optimization of several parameters such as extraction solvent, percentage of derivatization reagent, extraction time, pH, and ionic strength. The results from the optimal method showed that calibration ranging from 0.5 to 500 μg L⁻¹ could be achieved with the RSDs between 1.75% and 9.39%, and the limits of detection (LOD) are ranging from 0.01 to 0.12 μg L⁻¹ for the CPs. Moreover, the proposed LPME method was compared with solid-phase microextraction (SPME) coupled with on-fiber derivatization technique. The results suggested that using both methods are quite agreeable. Furthermore, the recoveries of LPME evaluated by spiked environmental samples ranged from 87.9% (3,5-DCP) to 114.7% (2,3,5,6-TeCP), and environmental water samples collected from the Pearl River were analyzed with the optimized LPME method, the concentrations of 18 CPs ranged from 0.0237 μg L⁻¹ (3,5-DCP) to 0.3623 μg L⁻¹ (2,3,6-TCP).     

A screening method for the detection of synthetic glucocorticosteroids in human urine by liquid chromatography–mass spectrometry based on class-characteristic fragmentation pathways

This paper describes a liquid chromatographic/tandem mass spectrometric (LC/MS–MS) method specifically designed for the screening of synthetic glucocorticosteroids in human urine. The method is designed to recognize a common mass spectral fragment formed from the particular portion of the molecular structure that is common to all synthetic glucocorticosteroids and that is fundamental to their pharmacological activity. As such, the method is also suitable for detecting unknown substances, provided they contain the portion of the molecular structure selected as the analytical target. The effectiveness of this approach was evaluated on seventeen synthetic glucocorticosteroids. Urine samples, including blank urines spiked with one or more synthetic glucocorticosteroids, were treated according to a standard procedure (enzymatic hydrolysis, liquid/liquid extraction and evaporation to dryness) and analyzed using LC/MS-MS with electrospray ionization (ESI). MS–MS acquisition was carried out in a precursor ion scan, and the results were compared with those obtained by a previously developed reference technique based on acquisition in the multiple reaction monitoring (MRM) mode. All of the glucocorticosteroids considered in this study are clearly detectable in urine, with a limit of detection in the concentration range 5–20 ng/mL, depending on the glucocorticosteroid structure. The proposed method is therefore suitable for the detection of glucocorticosteroids in urine samples taken for “in competition” sport anti-doping control tests, matching the requirements of the World Anti-Doping Agency (WADA) for accredited anti-doping laboratories. Figure Structures of the synthetic glucocorticoids considered in this study     

Automated thermochemolysis reactor for detection of Bacillus anthracis endospores by gas chromatography–mass spectrometry

An automated sample preparation system was developed and tested for the rapid detection of Bacillus anthracis endospores by gas chromatography–mass spectrometry (GC–MS) for eventual use in the field. This reactor is capable of automatically processing suspected bio-threat agents to release and derivatize unique chemical biomarkers by thermochemolysis (TCM). The system automatically controls the movement of sample vials from one position to another, crimping of septum caps onto the vials, precise delivery of reagents, and TCM reaction times and temperatures. The specific operations of introduction of sample vials, solid phase microextraction (SPME) sampling, injection into the GC–MS system, and ejection of used vials from the system were performed manually in this study, although they can be integrated into the automated system. Manual SPME sampling is performed by following visual and audible signal prompts for inserting the fiber into and retracting it from the sampling port. A rotating carousel design allows for simultaneous sample collection, reaction, biomarker extraction and analysis of sequential samples. Dipicolinic acid methyl ester (DPAME), 3-methyl-2-butenoic acid methyl ester (a fragment of anthrose) and two methylated sugars were used to compare the performance of the autoreactor with manual TCM. Statistical algorithms were used to construct reliable bacterial endospore signatures, and 24 out of 25 (96%) endospore-forming Bacillus species were correctly identified in a statistically designed test.     

Study of the microbiodegradation of terpenoid resin-based varnishes from easel painting using pyrolysis–gas chromatography–mass spectrometry and gas chromatography–mass spectrometry

The alterations produced by microbiological attack on terpenoid resin-based varnishes from panel and canvas paintings have been evaluated using pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) and gas chromatography–mass spectrometry (GC–MS). The proposed methods include the on-line derivatisation of drying oils and diterpenoid resins using hexamethyldisilazane during pyrolysis and the application of methyl chloroformate as a derivatisation reagent for triterpenoid resins in GC–MS. Two types of specimens, consisting of model oil medium prepared from linseed oil and model spirit varnishes prepared from colophony and mastic resins dissolved in turpentine, have been used as reference materials. For a series of specimens upon which different genera of bacteria and fungi were inoculated and encouraged to grow, analyses indicated that no mechanisms that commonly occur during the attack of enzymes on drying oils and terpenoid biodegraders were observed to occur in the oil medium and varnishes studied. Thus, the degradation pathways observed in the performed trials usually occur as consequence of natural ageing. Specific trials consisting of the application of biocides to uninoculated colophony varnish resulted in the identification of processes that produce undesirable degradation of the varnish due to interactions between the biocide and the varnish components. Finally, the studied biocides—Biotin, New-Des and Nipagine—generally exhibited good inhibiting effects on the microorganisms studied, although some interesting differences were found between them regarding the application method and type of biocide.     

Determination of tetrabromobisphenol-A,tetrachlorobisphenol-A and bisphenol-A in soil by ultrasonic assisted extraction and gas chromatography–mass spectrometry

In this work, an isotope dilution method for the determination, in agricultural and industrial soil samples, of tetrabromobisphenol-A, tetrachlorobisphenol-A and bisphenol-A by gas chromatography–mass spectrometry was developed. The compounds were extracted from soil by sonication assisted extraction in small columns (SAESC) with a low volume of ethyl acetate as extraction solvent. For dirty soil samples, such as industrial soils, a simultaneous clean-up on an acidified Florisil–anhydrous sodium sulfate mixture was carried out to remove interferences. After extraction, solvent was evaporated and analytes were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and determined by isotope dilution gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC–MS–SIM), using ¹³C₁₂ labeled compounds as internal standards. Recoveries from spiked samples were between 88% and 108% and the estimated limits of detection (S/N = 3) varied from 30 pg g⁻¹ to 90 pg g⁻¹. The response obtained with this method was linear over the range assayed, 5–300 ng ml⁻¹, with correlation coefficients equal or higher than 0.999. The validated method was used to investigate the levels of these phenolic compounds in soil samples collected from different locations in Spain. Bisphenol-A was detected in all samples at concentrations from 0.7 ng g⁻¹ to 4.6 ng g⁻¹ in agricultural soils and from 1.1 ng g⁻¹ to 44.5 ng g⁻¹ in industrial soils. Tetrabromobisphenol-A was found in various soil samples at levels in the range of 3.4–32.2 ng g⁻¹ in industrial soils and at 0.3 ng g⁻¹ in one agricultural soil, whereas tetrachlorobisphenol-A was not detected.     

Dispersive liquid–liquid microextraction followed by gas chromatography–mass spectrometry for the rapid and sensitive determination of UV filters in environmental water samples

The performance of the dispersive liquid–liquid microextraction (DLLME) technique for the determination of eight UV filters and a structurally related personal care species, benzyl salicylate (BzS), in environmental water samples is evaluated. After extraction, analytes were determined by gas chromatography combined with mass spectrometry detection (GC-MS). Parameters potentially affecting the performance of the sample preparation method (sample pH, ionic strength, type and volume of dispersant and extractant solvents) were systematically investigated using both multi- and univariant optimization strategies. Under final working conditions, analytes were extracted from 10 mL water samples by addition of 1 mL of acetone (dispersant) containing 60 μL of chlorobenzene (extractant), without modifying either the pH or the ionic strength of the sample. Limits of quantification (LOQs) between 2 and 14 ng L⁻¹, inter-day variability (evaluated with relative standard deviations, RSDs) from 9% to 14% and good linearity up to concentrations of 10,000 ng L⁻¹ were obtained. Moreover, the efficiency of the extraction was scarcely affected by the type of water sample. With the only exception of 2-ethylhexyl-p-dimethylaminobenzoate (EHPABA), compounds were found in environmental water samples at concentrations between 6 ± 1 ng L⁻¹ and 26 ± 2 ng mL⁻¹.     

Microwave-assisted extraction: a simpler and faster method for the determination of ethyl glucuronide in hair by gas chromatography–mass spectrometry

Alcohol is the most frequently abused “addictive substance” that causes serious social problems throughout the world; thus, alcoholism is of particular interest in clinical and forensic medicine. Alcohol biomarkers are physiological indicators of alcohol exposure or ingestion and may reflect the presence of an alcohol use disorder. The glucuronide conjugation is a minor pathway of ethanol metabolism. Ethyl glucuronide (EtG) is a marker of recent alcohol consumption that detects alcohol use reliably over a definite time period. The present paper describes a new method for the determination of EtG in hair. It is based both in the microwave-assisted extraction (MAE), to extract the analyte from hair samples, and gas chromatography–mass spectrometry (GC-MS), to identify and quantify the EtG in selected ion monitoring (SIM) mode. The method was applied to 15 hair samples from occasional alcohol users, obtaining positive results in all cases. It was fully validated, including a linear range (0.3–10 ng/mg) and the main precision parameters. In summary, the use of microwave-assisted extraction turned out to be a substantially simpler, faster, and a more sensitive procedure than any other conventional sample preparations.     

A new method for quantifying prenatal exposure to ethanol by microwave-assisted extraction (MAE) of meconium followed by gas chromatography–mass spectrometry (GC–MS)

Ethanol is a legal and widely available substance. There are health and social consequences associated with its abuse. One of the most important problems is related to alcohol consumption during pregnancy. In fact, prenatal ethanol exposure can be associated with fetal alcohol spectrum disorder (FASD), a term used to describe a wide range of potentially lifelong effects that include physical, mental, behavioral, and learning disabilities. Fatty acid ethyl esters (FAEEs), which are non-oxidative metabolites of ethanol, are currently used as biomarkers of direct ethanol consumption in different matrices, including hair, blood, skin surface, and meconium. Analysis of these compounds in meconium reveals exposure to alcohol during the second and third trimesters of pregnancy. An important finding for evaluation of gestational ethanol exposure is the fact that FAEEs do not cross the placenta. Because they accumulate in the fetal gut from approximately the 20th week of gestation until birth, this provides a wide window of detection of chronic exposure to alcohol. The sum of the concentrations of all the FAEEs, with a cutoff of 2 nmol g(-1) or 600 ng g(-1) meconium, has been recommended as evidence of maternal alcohol use. We introduce a novel technique to quantify ethyl myristate, ethyl palmitate, ethyl stearate, and their deuterated analogues (as internal standards, IS) in meconium using microwave-assisted extraction (MAE) coupled with gas chromatography-mass spectrometry (GC-MS). Limits of detection and quantification were 50 and 100 ng g(-1) for all analytes except ethyl stearate (LOD 100 ng g(-1) and LOQ 500 ng g(-1)). Calibration curves were linear from the LOQ to 5000 ng g(-1). The validated method was applied to the analysis of 81 meconium samples.     

Simple approach based on ultrasound-assisted emulsification-microextraction for determination of polibrominated flame retardants in water samples by gas chromatography–mass spectrometry

A simple, efficient, innovative and environmentally friendly analytical technique was successfully applied for the first time for the extraction and preconcentration of polybrominated diphenyl ethers (PBDEs) from water samples. The PBDEs selected for this work were those most commonly found in the literature in natural water samples: 2,2′,4,4′-tetraBDE (BDE-47), 2,2′,4,4,5-pentaBDE (BDE-99), 2,2′,4,4,6-pentaBDE (BDE-100) and 2,2,4,4′,5,5′-hexaBDE (BDE-153). The extracted PBDEs were separated and determined by gas chromatography–mass spectrometry (GC–MS). The extraction/preconcentration technique is based on ultrasound-assisted emulsification-microextraction (USAEME) of a water-immiscible solvent in an aqueous medium. Several variables including, solvent type, extraction time, extraction temperature and matrix modifiers were studied and optimized over the relative response the target analytes. Chloroform was used as extraction solvent in the USAEME technique. Under optimum conditions, the target analytes were quantitatively extracted achieving enrichment factors (EF) higher than 319. The detection limits (LODs) of the analytes for the preconcentration of 10 mL sample volume were within the range 1–2 pg mL⁻¹. The relative standard deviations (RSD) for five replicates at 10 pg mL⁻¹ concentration level were <10.3%. The calibration graphs were linear within the concentration range of 5–5000 pg mL⁻¹ for BDE-47 and BDE-100; and 5–10,000 pg mL⁻¹ for BDE-99 and BDE-153, respectively. The coefficients of estimation were ≥0.9985. Validation of the methodology was performed by standard addition method at two concentration levels (10 and 50 pg mL⁻¹). Recovery values were ≥96%, which showed a successful robustness of the analytical methodology for determination of picogram per milliliter of PBDEs in water samples. Significant quantities of PBDEs were not found in the analyzed samples.     

Fast gel permeation chromatography–mass spectrometry method for polymer and additive analysis

This study presents gel permeation chromatography (GPC) coupled with mass spectrometry (MS) as a suitable method to evaluate molecular weight distribution, oligomeric structure, and additives of commercial polystyrene resins in just 4?min. The chromatogram recorded by ultraviolet (UV) detection gives information on the high molecular mass fractions, while the mass detector provides knowledge on the chemical structure and concentration of oligomers and additives. A good agreement for the average molecular weights of the broad polystyrene reference SRM 706 and an excellent correlation with the expected isotope distributions for oligomers and additives were obtained using this fast GPC–UV–MS method.     

Fast low-pressure gas chromatography–mass spectrometry method for the determination of multiple pesticides in grapes,musts and wines

A fast method using low-pressure gas chromatography coupled to mass spectrometry (LP-GC/MS) was implemented and optimized to yield a complete separation of 27 representative pesticides in grapes, musts and wines. Extraction was performed with acetonitrile, applying quick, easy, cheap, effective, rugged and safe (QuEChERS) methodology. Several LP-GC/MS conditions such as column temperature, injection conditions, flow rate, MS conditions and matrix effects were evaluated to achieve the fastest separation with the highest sensitivity in MS detection (selected ion monitoring mode). After optimization, all 27 pesticides were extracted, chromatographically separated and detected in less than 20 min. Acceptable recoveries for nearly all pesticides at three different spiking levels (from 0.04 to 2.5 μg/g) were achieved with good repeatability (from 3 to 21%). Limits of quantification (from 0.02 to 5 μg/g) were lower than the maximum limit of residues, when established for pesticides.     

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.     

Determination of fragrance allergens in indoor air by active sampling followed by ultrasound-assisted solvent extraction and gas chromatography–mass spectrometry

Fragrances are ubiquitous pollutants in the environment, present in the most of household products, air fresheners, insecticides and cosmetics. Commercial perfumes may contain hundreds of individual fragrance chemicals. In addition to the widespread use and exposure to fragranced products, many of the raw fragrance materials have limited available health and safety data. Because of their nature as artificial fragrances, inhalation should be considered as an important exposure pathway, especially in indoor environments. In this work, a very simple, fast, and sensitive methodology for the analysis of 24 fragrance allergens in indoor air is presented. Considered compounds include those regulated by the EU Directive, excluding limonene; methyl eugenol was also included due to its toxicity. The proposed methodology is based on the use of a very low amount of adsorbent to retain the target compounds, and the rapid ultrasound-assisted solvent extraction (UAE) using a very low volume of solvent which avoids further extract concentration. Quantification was performed by gas chromatography coupled to mass spectrometry (GC–MS). The influence of main factors involved in the UAE step (type of adsorbent and solvent, solvent volume and extraction time) was studied using an experimental design approach to account for possible factor interactions. Using the optimized procedure, 0.2 m⁻³ air are sampled, analytes are retained on 25 mg Florisil, from which they are extracted by UAE (5 min) with 2 mL ethyl acetate. Linearity was demonstrated in a wide concentration range. Efficiency of the total sampling-extraction process was studied at several concentration levels (1, 5 and 125 μg m⁻³), obtaining quantitative recoveries, and good precision (RSD < 10%). Method detection limits were ≤0.6 μg m⁻³. Finally, the proposed method was applied to real samples collected in indoor environments in which several of the target compounds were determined.     

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.     

An automated headspace solid-phase microextraction followed by gas chromatography–mass spectrometry method to determine macrocyclic musk fragrances in wastewater samples

A fully automated method has been developed for determining eight macrocyclic musk fragrances in wastewater samples. The method is based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC-MS). Five different fibres (PDMS 7 μm, PDMS 30 μm, PDMS 100 μm, PDMS/DVB 65 μm and PA 85 μm) were tested. The best conditions were achieved when a PDMS/DVB 65 μm fibre was exposed for 45 min in the headspace of 10 mL water samples at 100 °C. Method detection limits were found in the low ng L^?1 range between 0.75 and 5 ng L^?1 depending on the target analytes. Moreover, under optimized conditions, the method gave good levels of intra-day and inter-day repeatabilities in wastewater samples with relative standard deviations (n?=?5, 1,000 ng L^?1) less than 9 and 14 %, respectively. The applicability of the method was tested with influent and effluent urban wastewater samples from different wastewater treatment plants (WWTPs). The analysis of influent urban wastewater revealed the presence of most of the target macrocyclic musks with, most notably, the maximum concentration of ambrettolide being obtained in WWTP A (4.36 μg L^?1) and WWTP B (12.29 μg L^?1), respectively. The analysis of effluent urban wastewater showed a decrease in target analyte concentrations, with exaltone and ambrettolide being the most abundant compounds with concentrations varying between below method quantification limit (<MQL) and 2.46 μg L^?1.