The Experts below are selected from a list of 159 Experts worldwide ranked by ideXlab platform
Adam Tolgyesi - One of the best experts on this subject based on the ideXlab platform.
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quantitative determination of corticosteroids in bovine milk using mixed mode polymeric strong cation exchange solid phase extraction and liquid chromatography tandem mass spectrometry
Journal of Pharmaceutical and Biomedical Analysis, 2010Co-Authors: Adam Tolgyesi, Virender K Sharma, Laszlo Tolgyesi, Mary Sohn, Jenő FeketeAbstract:A new method was developed to identify and quantify corticosteroids (prednisolone, methylprednisone, Flumetasone, dexamethasone, and methylprednisolone) in raw bovine milk by liquid chromatography-tandem mass spectrometry (LC-MS/MS) utilizing mixed-mode polymeric strong cation exchange and reversed-phase (MCX) solid-phase extraction (SPE) to reduce ion effects in a multimode ion (MMI) source. The main advantage of this method over other commonly used methods includes the use of a single SPE cartridge with a low volume for sample preparation and fast separation on the HPLC system with reduced ion suppression. This study is the first to report the determination of methylprednisone, a metabolite of methylprednisolone, in bovine milk. This method was validated in accordance with the European Union (EU) Commission Decision 2002/657/EC. The recoveries vary between 90% and 105%. The within-laboratory reproducibility (precision) is less than 30%. The decision limits and detection capabilities were calculated along with LODs, which ranged from 0.02 to 0.07 microg/kg. The method was further enhanced by its successful adaptation to other LC-MS/MS systems equipped with the newly developed ion source, Agilent Jet Stream (AJS). After optimization of the AJS ion source and MS parameters, even lower LOD values were achieved (0.001-0.006 microg/kg) for the corticosteroids. Analytical results obtained with the AJS were characterized by an enhanced area response and similar noise level comparable to those obtained with conventional orthogonal atmospheric ionization (API).
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simultaneous determination of corticosteroids androgens and progesterone in river water by liquid chromatography tandem mass spectrometry
Chemosphere, 2010Co-Authors: Adam Tolgyesi, Zita Verebey, Virender K Sharma, Lorena Kovacsics, Jeno FeketeAbstract:Abstract The assessment of steroidal hormones in the environment requires sensitive and selective analytical techniques suitable for sample matrices. This paper reports a simple method to analyze simultaneously six corticosteroids (triamcinolone, cortisol, dexamethasone, flumethasone, prednisolone, triamcinolone acetonide), four androgens (boldenone, epitestosterone, methyltestosterone, nortestosterone), and progesterone in river and drinking water sources. The developed method is based on a single solid-phase extraction (SPE) followed by liquid chromatography/tandem mass spectrometry (LC–MS/MS) with atmospheric pressure chemical ionization (APCI). The main advantage of this method over other methods includes the use of a single SPE with a low volume cartridge for sample preparation, separation of steroids on alkyl-amide stationary phase with no matrix interferences by LC–MS/MS analysis, and simultaneous analysis of more than two groups of steroids. The method was characterized by generally good performance, analyzing three groups of steroids using 100 and 1000 mL samples with average recovery ranges of 80–109% and 68–126%, respectively at a level of 1 ng L −1 . The limit of detection (LOD) ranged from 0.06 to 0.2 and 0.01–0.21 ng L −1 for 100 mL and 1000 mL samples volumes, respectively. Sixty samples of Danube River and drinking water sources from different regions of Hungary were collected to analyze target steroids in two sampling periods in 2008 and 2009. Steroids, except cortisol, dexamethasone, flumethasone, prednisolone, epitestosterone and progesterone were below detection limits. Endogenous steroids (cortisol, epitestosterone, progesterone) were present in the concentration range of 0.08–2.67 ng L −1 while synthetic corticosteroids (dexamethasone, flumethasone, and prednisolone) varied from 0.064 to 1.43 ng L −1 . Steroids were present in river water, except progesterone, which was present only in ground water. Levels of steroids are compared with other rivers in the world and were briefly discussed.
Mikael Pedersen - One of the best experts on this subject based on the ideXlab platform.
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optimization of solid phase extraction clean up and validation of quantitative determination of corticosteroids in urine by liquid chromatography tandem mass spectrometry
Analytica Chimica Acta, 2008Co-Authors: Jens Hinge Andersen, Lene Hansen, Mikael PedersenAbstract:A solid phase extraction (SPE) method for extraction and clean up of 9 synthetic corticosteroids was optimized for quantification by reversed-phase high-performance liquid chromatography/negative electrospray ionisation mass spectrometry. Clean up was accomplished using a mixed mode polymeric strong anion exchange SPE column. The final method was validated according to EU regulations for determination of residues of veterinarian drugs in products of animal origin. Initial results showed a large difference in ion suppression between samples of porcine and bovine urine. The aim of optimisation was to design a procedure that minimised this difference while using a single SPE procedure and a fast HPLC method that enabled sufficient separation of the epimers beta- and dexamethasone. To include conjugated corticosteroids in the analysis, the sample was hydrolysed with Helix Pomatia beta-glucuronidase/aryl sulfatase. For the final method, which included fluocinolone acetonid, triamcinolone acetonid, beclomethasone, flumethasone, dexamethasone, betamethasone, 6alpha-methylprednisolone, prednisone and prednisolone, a quantification based on spiked samples carried through the entire analytical procedure was used. For quantification of triamcinolone acetonid an internal standard (triamcinolone acetonid-D6) was used. Relative average recoveries from 96 to 103% were found, except for beclomethasone (113%). Absolute average recoveries were 81-99%. Quantification limits (decision limits, CCalpha) were demonstrated to be not higher than 1 microg L(-1) (3 microg L(-1) for prednisone and prednisolone). The internal reproducibility, determined by triplicates from spiking at three different levels in six analytical series was 7-19% (at 2-4 microg L(-1)) except for prednisone and prednisolone (26-27% at 3-6 microg L(-1)).
Virender K Sharma - One of the best experts on this subject based on the ideXlab platform.
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quantitative determination of corticosteroids in bovine milk using mixed mode polymeric strong cation exchange solid phase extraction and liquid chromatography tandem mass spectrometry
Journal of Pharmaceutical and Biomedical Analysis, 2010Co-Authors: Adam Tolgyesi, Virender K Sharma, Laszlo Tolgyesi, Mary Sohn, Jenő FeketeAbstract:A new method was developed to identify and quantify corticosteroids (prednisolone, methylprednisone, Flumetasone, dexamethasone, and methylprednisolone) in raw bovine milk by liquid chromatography-tandem mass spectrometry (LC-MS/MS) utilizing mixed-mode polymeric strong cation exchange and reversed-phase (MCX) solid-phase extraction (SPE) to reduce ion effects in a multimode ion (MMI) source. The main advantage of this method over other commonly used methods includes the use of a single SPE cartridge with a low volume for sample preparation and fast separation on the HPLC system with reduced ion suppression. This study is the first to report the determination of methylprednisone, a metabolite of methylprednisolone, in bovine milk. This method was validated in accordance with the European Union (EU) Commission Decision 2002/657/EC. The recoveries vary between 90% and 105%. The within-laboratory reproducibility (precision) is less than 30%. The decision limits and detection capabilities were calculated along with LODs, which ranged from 0.02 to 0.07 microg/kg. The method was further enhanced by its successful adaptation to other LC-MS/MS systems equipped with the newly developed ion source, Agilent Jet Stream (AJS). After optimization of the AJS ion source and MS parameters, even lower LOD values were achieved (0.001-0.006 microg/kg) for the corticosteroids. Analytical results obtained with the AJS were characterized by an enhanced area response and similar noise level comparable to those obtained with conventional orthogonal atmospheric ionization (API).
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simultaneous determination of corticosteroids androgens and progesterone in river water by liquid chromatography tandem mass spectrometry
Chemosphere, 2010Co-Authors: Adam Tolgyesi, Zita Verebey, Virender K Sharma, Lorena Kovacsics, Jeno FeketeAbstract:Abstract The assessment of steroidal hormones in the environment requires sensitive and selective analytical techniques suitable for sample matrices. This paper reports a simple method to analyze simultaneously six corticosteroids (triamcinolone, cortisol, dexamethasone, flumethasone, prednisolone, triamcinolone acetonide), four androgens (boldenone, epitestosterone, methyltestosterone, nortestosterone), and progesterone in river and drinking water sources. The developed method is based on a single solid-phase extraction (SPE) followed by liquid chromatography/tandem mass spectrometry (LC–MS/MS) with atmospheric pressure chemical ionization (APCI). The main advantage of this method over other methods includes the use of a single SPE with a low volume cartridge for sample preparation, separation of steroids on alkyl-amide stationary phase with no matrix interferences by LC–MS/MS analysis, and simultaneous analysis of more than two groups of steroids. The method was characterized by generally good performance, analyzing three groups of steroids using 100 and 1000 mL samples with average recovery ranges of 80–109% and 68–126%, respectively at a level of 1 ng L −1 . The limit of detection (LOD) ranged from 0.06 to 0.2 and 0.01–0.21 ng L −1 for 100 mL and 1000 mL samples volumes, respectively. Sixty samples of Danube River and drinking water sources from different regions of Hungary were collected to analyze target steroids in two sampling periods in 2008 and 2009. Steroids, except cortisol, dexamethasone, flumethasone, prednisolone, epitestosterone and progesterone were below detection limits. Endogenous steroids (cortisol, epitestosterone, progesterone) were present in the concentration range of 0.08–2.67 ng L −1 while synthetic corticosteroids (dexamethasone, flumethasone, and prednisolone) varied from 0.064 to 1.43 ng L −1 . Steroids were present in river water, except progesterone, which was present only in ground water. Levels of steroids are compared with other rivers in the world and were briefly discussed.
Jenő Fekete - One of the best experts on this subject based on the ideXlab platform.
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quantitative determination of corticosteroids in bovine milk using mixed mode polymeric strong cation exchange solid phase extraction and liquid chromatography tandem mass spectrometry
Journal of Pharmaceutical and Biomedical Analysis, 2010Co-Authors: Adam Tolgyesi, Virender K Sharma, Laszlo Tolgyesi, Mary Sohn, Jenő FeketeAbstract:A new method was developed to identify and quantify corticosteroids (prednisolone, methylprednisone, Flumetasone, dexamethasone, and methylprednisolone) in raw bovine milk by liquid chromatography-tandem mass spectrometry (LC-MS/MS) utilizing mixed-mode polymeric strong cation exchange and reversed-phase (MCX) solid-phase extraction (SPE) to reduce ion effects in a multimode ion (MMI) source. The main advantage of this method over other commonly used methods includes the use of a single SPE cartridge with a low volume for sample preparation and fast separation on the HPLC system with reduced ion suppression. This study is the first to report the determination of methylprednisone, a metabolite of methylprednisolone, in bovine milk. This method was validated in accordance with the European Union (EU) Commission Decision 2002/657/EC. The recoveries vary between 90% and 105%. The within-laboratory reproducibility (precision) is less than 30%. The decision limits and detection capabilities were calculated along with LODs, which ranged from 0.02 to 0.07 microg/kg. The method was further enhanced by its successful adaptation to other LC-MS/MS systems equipped with the newly developed ion source, Agilent Jet Stream (AJS). After optimization of the AJS ion source and MS parameters, even lower LOD values were achieved (0.001-0.006 microg/kg) for the corticosteroids. Analytical results obtained with the AJS were characterized by an enhanced area response and similar noise level comparable to those obtained with conventional orthogonal atmospheric ionization (API).
Gianfranco Brambilla - One of the best experts on this subject based on the ideXlab platform.
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determination of flumethasone in calf urine and serum by liquid chromatography tandem mass spectrometry
Journal of Chromatography B: Biomedical Sciences and Applications, 2001Co-Authors: Gianfranco Brambilla, Francesca Buiarelli, G P Cartoni, F Coccioli, C Colamonici, A Fagiolo, C Giannini, B NeriAbstract:Abstract Corticosteroids can be illegally administered to cattle as growth promoting agents to improve meat production. We developed a liquid chromatography–atmospheric pressure ionization mass spectrometry–mass spectrometry (LC–MS–MS) method able to identify and quantify flumethasone, one of the most potent fluorinated synthetic corticosteroid, in serum and urine from treated calves. The analyte was purified from urine (conjugated and free, following enzymatic hydrolysis) and from serum by C18 solid-phase and liquid–liquid extractions, then analyzed by LC–MS–MS monitoring the product ions of an abundant precursor (SRM in negative ionization mode). Results on flumethasone residues in biological fluids in three calves treated at different levels are presented. This method allowed the detection of flumethasone in bovine urine and serum at the 30-pg/ml level.
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identification of main corticosteroids as illegal feed additives in milk replacers by liquid chromatography atmospheric pressure chemical ionisation mass spectrometry
Journal of Chromatography A, 1998Co-Authors: Maurizio Fiori, Elio Pierdominici, Francesca Longo, Gianfranco BrambillaAbstract:Abstract Corticosteroids were proposed as growth promoting agents to improve commercial quality of meat. We developed a liquid chromatography–atmospheric pressure chemical ionisation mass spectrometry (LC–APCI-MS) method able to identify the presence in milk replacers, when given by mouth, of dexamethasone, betamethasone, flumethasone, triamcinolone, prednisone, prednisolone, methylprednisolone, fludrocortisone and beclomethasone, at levels in the range of 20–100 ppb. C 18 solid-phase extraction, LC-RP C 8 column separation, data acquisition (positive ions) in the scan range m / z 200–550 allowed us to differentiate and identify compounds by protonated molecules, their methanolic adducts and fragmentation patterns.