The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Andrzej Posyniak - One of the best experts on this subject based on the ideXlab platform.
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analysis of thyreostats in bovine feces using ultra high performance liquid chromatography with tandem mass spectrometry
IEEE Journal of Solid-state Circuits, 2018Co-Authors: Sebastian Witek, Barbara Wozniak, Iwona Matraszekzuchowska, Andrzej PosyniakAbstract:A method based on ultra-high performance liquid chromatography was developed and validated to detect six thyreostatic compounds: tapazole, thiouracil, Methylthiouracil, diMethylthiouracil, propylthiouracil, and phenylthiouracil in faeces of bovine. Thyreostats were extracted from the matrix with a mixture of methanol and buffer (pH = 8). Next step was derivatization of analytes with 3-iodobenzylbromide. The liquid chromatographic separation of derivatives was obtained on a SB-C18 column (50 × 2.1 mm; 1.8 μm, Agilent) with gradient elution using a mobile phase consisting of acetonitrile/0.1% acetic acid within 7.5 min. The analysis was performed on a Shimadzu NEXERA X2 ultra-high performance liquid chromatograph with triple quadrupole MS 8050 instrument operating in positive electrospray ionization mode. Depending on the target compound, two or three diagnostic signals (selected reaction monitoring transitions) were monitored. The procedure was validated according to the Commission Decision 2002/657/EC. Recovery and repeatability met the performance criteria specified by this document for banned compounds. The recovery ranged from 97.5 to 110.5%, and repeatability did not exceed 14.1%. Decision limits and detection capabilities were below 10 μg/kg. The highest decision limits and detection capabilities concentrations were observed for phenylthiouracil of 3.48 and 6.96 μg/kg, respectively.
Bruno Le Bizec - One of the best experts on this subject based on the ideXlab platform.
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determination of thyreostats in urine and thyroid gland by ultra high performance liquid chromatography tandem mass spectrometry
Journal of Chromatography A, 2009Co-Authors: Madis Lohmus, Kalle Kallaste, Bruno Le BizecAbstract:Abstract Thyreostatic compounds could be illegally administered to animals in order to obtain a weight gain due to a higher retention of water in the edible tissue and the gastro-intestinal tract. In the European Union their use for animal production is banned since 1981. Recently a highly sensitive method exploiting the determination of thyreostats with 3-iodobenzylbromide prior to purification to determine thyreostats in urine and other matrices was reported. For the first time, the UPLC instrumentation was used to separate the 3-iodobenzyl derivatives of various thyreostats. The deuterated internal standards tapazole-d3 and propylthiouracil-d5 were for the first time used for the quantification of tapazole, thiouracil, Methylthiouracil, propylthiouracil, phenylthiouracil and mercaptobenzimidazole. The confirmative quantitative liquid chromatographic tandem mass spectrometric (LC–MS/MS) method was validated according to Commission Decision 2002/657/EC. The decision limit (CCα) and the detection capability (CCβ) were found to be for all compounds below the recommended value of 10 μg kg−1.
Sebastian Witek - One of the best experts on this subject based on the ideXlab platform.
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analysis of thyreostats in bovine feces using ultra high performance liquid chromatography with tandem mass spectrometry
IEEE Journal of Solid-state Circuits, 2018Co-Authors: Sebastian Witek, Barbara Wozniak, Iwona Matraszekzuchowska, Andrzej PosyniakAbstract:A method based on ultra-high performance liquid chromatography was developed and validated to detect six thyreostatic compounds: tapazole, thiouracil, Methylthiouracil, diMethylthiouracil, propylthiouracil, and phenylthiouracil in faeces of bovine. Thyreostats were extracted from the matrix with a mixture of methanol and buffer (pH = 8). Next step was derivatization of analytes with 3-iodobenzylbromide. The liquid chromatographic separation of derivatives was obtained on a SB-C18 column (50 × 2.1 mm; 1.8 μm, Agilent) with gradient elution using a mobile phase consisting of acetonitrile/0.1% acetic acid within 7.5 min. The analysis was performed on a Shimadzu NEXERA X2 ultra-high performance liquid chromatograph with triple quadrupole MS 8050 instrument operating in positive electrospray ionization mode. Depending on the target compound, two or three diagnostic signals (selected reaction monitoring transitions) were monitored. The procedure was validated according to the Commission Decision 2002/657/EC. Recovery and repeatability met the performance criteria specified by this document for banned compounds. The recovery ranged from 97.5 to 110.5%, and repeatability did not exceed 14.1%. Decision limits and detection capabilities were below 10 μg/kg. The highest decision limits and detection capabilities concentrations were observed for phenylthiouracil of 3.48 and 6.96 μg/kg, respectively.
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liquid chromatography tandem mass spectrometry with ion trap and triple quadrupole analyzers for determination of thyreostatic drugs in urine and muscle tissue
Analytical Abstracts, 2012Co-Authors: Barbara Wozniak, Sebastian Witek, Iwona Matraszek Zuchowska, Jan Zmudzki, Piotr Jedziniak, Beata Korycinska, Katarzyna Sielska, Alicja KlopotAbstract:Liquid chromatography tandem mass spectrometry methods were developed and validated to screen for and confirm residues of the thyreostatic drugs: tapazole, thiouracil, Methylthiouracil, propylthiouracil, and phenylthiouracil in bovine and porcine urine and muscle tissues using diMethylthiouracil as internal standard. Thyreostats were extracted from urine samples with diethyl ether after derivatisation with 3-iodobenzylbromide in basic medium (pH 8.0) and analyzed by gradient elution on a Nucleosil C18 column with ion trap mass spectrometry detection using an electrospray source and triple quadrupole MS detection with turbo spray source. Thyreostats were extracted from muscle tissue with methanol, the denaturation of matrix protein was performed and then the same steps as for the urine samples were carried out. The methods were validated in accordance with the Commission Decision 2002/657/EC. Good thyreostats recoveries were obtained (from 82% to 117%) as well as acceptable within-lab reproducibility. The values of the decision limit CCα and the detection capability CCβ of five thyreostatic drugs are found to be below the recommended concentration set at 10 µg L–1 (kg–1). The results of the validation demonstrate that liquid chromatography mass spectrometry with ion trap detection does not meet the criteria for confirmation for some thyreostats and therefore was applied for screening purpose only.
D Courtheyn - One of the best experts on this subject based on the ideXlab platform.
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determination of mercaptobenzimidazol and other thyreostat residues in thyroid tissue and meat using high performance liquid chromatography mass spectrometry
Journal of Chromatography A, 2001Co-Authors: K De Wasch, H Be F Brabander, Sandra Impens, M Vandewiele, D CourtheynAbstract:This paper describes a method for extraction of tapazol, thiouracil, Methylthiouracil, propylthiouracil and mercaptobenzimidazol (MBI) from thyroid tissue. The solid-phase extraction procedure is optimized to obtain the maximum results for the main thyreostats including MBI. Different combinations of sample application, column conditioning and wash steps were tested. The analytes were extracted from the matrix with methanol. After solid-phase extraction they were derivatised with 7-chloro-4-nitrobenzo-2-furazan. Determination is carried out using liquid chromatography-electrospray mass spectrometry. The identification of the analytes was performed according to the final revision of the EU criteria (93/256/EC decision). The detection capability was 20 microg kg(-1) for all mentioned thyreostats.
Barbara Wozniak - One of the best experts on this subject based on the ideXlab platform.
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analysis of thyreostats in bovine feces using ultra high performance liquid chromatography with tandem mass spectrometry
IEEE Journal of Solid-state Circuits, 2018Co-Authors: Sebastian Witek, Barbara Wozniak, Iwona Matraszekzuchowska, Andrzej PosyniakAbstract:A method based on ultra-high performance liquid chromatography was developed and validated to detect six thyreostatic compounds: tapazole, thiouracil, Methylthiouracil, diMethylthiouracil, propylthiouracil, and phenylthiouracil in faeces of bovine. Thyreostats were extracted from the matrix with a mixture of methanol and buffer (pH = 8). Next step was derivatization of analytes with 3-iodobenzylbromide. The liquid chromatographic separation of derivatives was obtained on a SB-C18 column (50 × 2.1 mm; 1.8 μm, Agilent) with gradient elution using a mobile phase consisting of acetonitrile/0.1% acetic acid within 7.5 min. The analysis was performed on a Shimadzu NEXERA X2 ultra-high performance liquid chromatograph with triple quadrupole MS 8050 instrument operating in positive electrospray ionization mode. Depending on the target compound, two or three diagnostic signals (selected reaction monitoring transitions) were monitored. The procedure was validated according to the Commission Decision 2002/657/EC. Recovery and repeatability met the performance criteria specified by this document for banned compounds. The recovery ranged from 97.5 to 110.5%, and repeatability did not exceed 14.1%. Decision limits and detection capabilities were below 10 μg/kg. The highest decision limits and detection capabilities concentrations were observed for phenylthiouracil of 3.48 and 6.96 μg/kg, respectively.
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liquid chromatography tandem mass spectrometry with ion trap and triple quadrupole analyzers for determination of thyreostatic drugs in urine and muscle tissue
Analytical Abstracts, 2012Co-Authors: Barbara Wozniak, Sebastian Witek, Iwona Matraszek Zuchowska, Jan Zmudzki, Piotr Jedziniak, Beata Korycinska, Katarzyna Sielska, Alicja KlopotAbstract:Liquid chromatography tandem mass spectrometry methods were developed and validated to screen for and confirm residues of the thyreostatic drugs: tapazole, thiouracil, Methylthiouracil, propylthiouracil, and phenylthiouracil in bovine and porcine urine and muscle tissues using diMethylthiouracil as internal standard. Thyreostats were extracted from urine samples with diethyl ether after derivatisation with 3-iodobenzylbromide in basic medium (pH 8.0) and analyzed by gradient elution on a Nucleosil C18 column with ion trap mass spectrometry detection using an electrospray source and triple quadrupole MS detection with turbo spray source. Thyreostats were extracted from muscle tissue with methanol, the denaturation of matrix protein was performed and then the same steps as for the urine samples were carried out. The methods were validated in accordance with the Commission Decision 2002/657/EC. Good thyreostats recoveries were obtained (from 82% to 117%) as well as acceptable within-lab reproducibility. The values of the decision limit CCα and the detection capability CCβ of five thyreostatic drugs are found to be below the recommended concentration set at 10 µg L–1 (kg–1). The results of the validation demonstrate that liquid chromatography mass spectrometry with ion trap detection does not meet the criteria for confirmation for some thyreostats and therefore was applied for screening purpose only.