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ABSTRACT: Glucocorticoids constitute a class of molecules widely used in animal husbandry. Some of these compounds are licensed for veterinary practices while their use for growth promoting purposes is prohibited within the European Union. In order to ensure the respect of the legislation and consumers safety, several methodologies have been proposed to monitor these substances in various products, including edible matrices for which a regulatory limit has been set up (MRL). An extended range of targeted analytes together with reduced time of analysis and cost are however still current challenges regularly revisited according to the continuous technological improvements. In this context, the aim of the present study was to develop and implement a new fast and multi-residue method based on UHPLC-MS/MS for the determination of twenty glucocorticoids in bovine milk, included the screening of the three regulated MRL compounds (dexamethasone, betamethasone and prednisolone). This validated method authorises such multi-analyte measurement within a 10min runtime while the signal specificity is ensured through the SRM acquisition mode. Decision limits and detection capabilities were calculated in the range of 0.001-0.363μgL(-1), which allows a very efficient control at low trace level for a potential illegal use of these substances. The performances obtained in terms of application range, selectivity and sensitivity were found to be significantly improved in comparison to other reported approaches either for screening or confirmation purposes: regarding linearity, correlation coefficients were above 0.98 within the range of 0.01-5.0μgL(-1), repeatability and reproducibility parameters ranged from 1 to 30% with the maximum relative standard deviation (RSD) observed for cortisone (30.1%). Stability of the stock solutions and minor changes in the standard operating procedure have been included for the determination of ruggedness of the method. Identification was systematically ensured according to 4 identification points, RSD of transitions ratio (T2/T1) ranged from 3.2% and 19.3% and the RSD of the retention time was lower than 0.25%.
Journal of chromatography. A 04/2013; · 4.19 Impact Factor
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ABSTRACT: Perfluorinated compounds (PFCs) are usually monitored by high-performance liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) on triple quadrupole instruments. Although not yet widely implemented in the field, high-resolution mass spectrometry (HRMS) today appears as a valuable alternative for these halogenated chemicals due to their significant mass defect. Indeed, this second approach offers a way to cope with particular matrix effects caused by co-eluting and isobaric interferences affecting the measurement of some PFCs in fish. The present study compares three different LC-MS-related instruments and various signal acquisition modes, from low-resolution full-scan and selected ion-monitoring (SIM) mode on a triple quadrupole (QqQ) instrument to high-resolution full-scan or product ion-scan mode on orbital trap (LTQ-Orbitrap) or quadrupole-time-of-flight (Q-TOF) devices. Performances are compared for seven model compounds belonging to seven PFCs subclasses: perfluoralkylsulfonate, perfluoroalkylcarboxylate, perfluoroalkylsulfinate, perfluoroalkyl-sulfonamide, fluorotelomer saturated acid, fluorotelomer unsaturated acid and perfluoroalkylphosphonic acid. Low-resolution MS/MS was found to be unsurprisingly reliable for extended multi-residue monitoring. However, the high stability of PFCs leads to a relatively poor and non-specific fragmentation pathway in MS/MS. In addition, biliary acid-interfering compounds (e.g. taurochenodeoxycholic acid), which where encountered in the present case in fish samples but that may be present in other biological samples, were found particularly disturbing in low-resolution MS/MS. Indeed, these interferences presented the same retention time and diagnostic signals as PFOS, leading to a possible overestimation of the PFOS quantification in LC-MS/MS. On the other hand, high-resolution MS and MS/MS (LTQ-Orbitrap and Q-TOF) provided better results in terms of signal specificity and sensitivity. For instance, the estimated limits of detection (LOD) reached for PFOS on QqQ, Q-TOF and LTQ-Orbitrap instruments were 3.8, 0.7 and 0.5 pg injected, respectively.
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment 06/2011; 28(9):1261-73.
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ABSTRACT: The occurrence of the main steroid hormones (oestrone, 17alpha-oestradiol, 17beta-oestradiol, 17alpha-testosterone, 17beta-testosterone, dehydroepiandrosterone, 4-androstenedione), especially in milk and eggs, was investigated. An analytical method based on GC-MS/MS was developed for steroid measurement at an ultra-trace level in food products. The limits of detection for oestrogens were about 5 and 30 ng kg(-1) in milk and eggs, respectively. For androgens, the limits of detection were around 10 and 50 ng kg(-1) in milk and eggs, respectively. The method was applied to milk and egg samples collected in a French supermarket. In milk, oestrone was found at levels between 100 and 300 ng l(-1), while 17beta-oestradiol levels were estimated to be near 20 ng l(-1). 17alpha-testosterone was found to be from 50 ng l(-1) in skimmed milk to 85 ng l(-1) in whole milk. In egg samples, oestrone and 17beta-oestradiol were found at 1.5 and 0.9 microg kg(-1), respectively, while 17alpha-oestradiol was found to be in lower concentrations (i.e. around 0.55 microg kg(-1)). Regarding androgens, 17alpha- and 17beta-testosterone were estimated at 1.9 and 1.3 microg kg(-1), respectively. These results represent a first attempt to estimate the food exposure to steroid hormones. In the future, the collection of additional data should permit the comparison between this exogenous dietary intake and the daily endogenous production in pre-pubertal children as a basis of risk assessment regarding endocrine disruption linked to these molecules for this critical population.
Food Additives and Contaminants 01/2008; 24(12):1358-66. · 2.13 Impact Factor
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ABSTRACT: A residue is a trace (microg kg(-1), ng kg(-1)) of a substance, present in a matrix. Banned substances, such as growth promoters, which are abused in animal fattening and where this article is focused on, may be divided into four major groups: thyreostats, anabolics or anabolic steroids, corticosteroids and beta-agonists or repartitioning agents. The combination of chromatographic techniques with mass spectrometry (GC-MS(n), LC-MS(n), etc.) plays a key role in the production of specific results in residue analysis. In this review, the past, present and future of mass spectrometry in this area are discussed in the light of the impact of these substances on human health and the reliable production of analytical results, ready for challenge in a court.
Journal of Mass Spectrometry 09/2007; 42(8):983-98. · 3.27 Impact Factor
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ABSTRACT: Fifty years after the discovery of natural corticosteroid hormones and their anti-inflammatory properties many synthetic derivatives of these molecules are now available. Most are widely used in human and veterinary medicine, legally but under regulated conditions. These compounds can also be used as growth promoters in animal breeding, although such use is illegal in Europe. Consequently, analytical methods have been developed to monitor use of corticosteroids in cattle. This paper, based on the authors experience and the main relevant literature, describes the different mass spectrometric approaches used for measurement of corticosteroid residues (parent drug, metabolites, and esters) in biological matrices (urine, meat, hair), including gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–tandem mass spectrometry (LC–MS2). The respective advantages of liquid chromatography and gas chromatography, in conjunction with different derivatisation reactions, are discussed. The behavior of corticosteroids with different ionization techniques is also discussed. Application to monitoring corticosteroid misuse and to investigation of pharmacokinetics and metabolism in bovine species is described and new data are presented relating to elimination and hair fixation kinetics for free and ester forms and the nature and proportions of corticosteroid phase I and phase II metabolites. Finally, this work reviews ten years experience of the use of a variety of mass spectrometric techniques for analysis of corticosteroids in animals produced as food.
Chromatographia 02/2004; 59:S13-S22. · 1.20 Impact Factor
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ABSTRACT: A new method has been developed for the simultaneous measurement, in a reduced plasma sample, of concentration and 13C-isotopic enrichment of acetic, propionic, butyric, lactic, acetoacetic and beta-hydroxybutyric acids by gas chromatography coupled to mass spectrometry. After plasma deproteinisation, a diethylic extraction and a N-tert.-butyldimethylsilyl-N-methyltrifluoroacetamide derivatisation were performed. Both diethyl extraction and derivatisation procedures were optimised using the central composite designs methodology. The optimised method provides good linearity, intra-day and within-day repeatability. Except for beta-hydroxybutyric (49 microM) and acetoacetic acid (5 microM), detection limits were ranging between 0.2 and 0.7 microM allowing uses of this method for colonic metabolism studies.
Journal of Chromatography B 03/2003; 784(2):395-403. · 2.89 Impact Factor
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ABSTRACT: A fast and efficient multi-residue extraction-purification procedure was developed for 12 corticosteroids in biological matrices (hair, urine and meat), in order to control their illegal use as growth promoters in cattle. Detection and identification of the analytes were achieved using a previously described LC-MS-MS method based on negative electrospray ionisation and a triple quadrupole analyser. The presented procedures included acid (hair) or enzymatic (urine and meat) hydrolysis, C18 reversed-phase SPE, Na2CO3 liquid-liquid clean-up and SiOH normal-phase SPE. The detection limits of the developed methods were between 2.9 and 9.3 pg/mg (ppb) for hair samples and in the 40 - 70 pg/g (ppt) range for the urine or meat samples. The acid hydrolysis used for corticosteroid extraction in hair was optimised using an experimental design and response surface methodology. Achieved performances were linked to a physico-chemical approach based on the corticosteroids specific C17 side-chain. This original multi-residue and multi-matrices analytical methodology will be used for further metabolism studies.
Journal of chromatography. B, Biomedical sciences and applications 07/2001; 757(1):11-9.
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ABSTRACT: A screening method based on liquid chromatography/electrospray tandem mass spectrometry was developed in order to control the illegal use of corticosteroids as growth promoters in cattle. The objective was the detection of low residue levels of corticosteroids or metabolites in biological matrices. Relative to other studies published on this subject, the present work focused on enhancing specificity and sensitivity. Firstly, fragmentation of corticosteroids by collision-induced dissociation was studied. In positive mode, the losses of H(2)O for each hydroxyl group fixed on the molecule, as well as the loss of HF or HCl for halogenated compounds, were observed. For higher collision energy, fragmentations in the B, C and D rings were induced. The negative mode was found to be more specific, inducing a cleavage of the C(20)-C(21) bond with concomitant loss of formaldehyde (CH(2)O). Secondly, three acquisition methods in the negative mode were studied and evaluated, recorded signals being the parent ion [M + acetate](-) and the two daughter ions, [M - H](-) and [M - H - CH(2)O](-). For dexamethasone, MS/MS instrumental detection limits of fragment ion and neutral loss scans, and of multiple reaction monitoring (MRM), were 250, 20 and 5 pg injected, respectively. The MRM method was then evaluated with the objective of use for the detection of corticosteroid residues in biological samples (urine, hair, muscle) and for a metabolism study.
Rapid Communications in Mass Spectrometry 02/2000; 14(1):33-9. · 2.79 Impact Factor
