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Open access

Anna Gajda and Andrzej Posyniak

Abstract

A liquid chromatography – tandem mass spectrometry (LC-MS/MS) method for the determination of oxytetracycline (OTC), 4-epi oxytetracycline (4-epi OTC), tetracycline (TC), 4-epi tetracycline (4-epi TC), chlortetracycline (CTC), 4-epi chlortetracycline (4-epi CTC), doxycycline (DC), minocycline (MINO), methacycline (META) and rolitetracycline (ROLI) residues in muscles was developed. The procedure consisted of an oxalic acid extraction followed by protein removal with trichloroacetic acid. Further solid phase clean-up on polymeric (Strata X) reversed phase columns was performed to obtain an extract suitable for LC-MS/MS analysis. The tetracyclines were separated on a C 18 analytical column with mobile phase consisting of 0.01% formic acid in acetonitrile and 0.01% formic acid in water in gradient mode. The method was validated according to the Commission Decision 2002/657/EC. The recoveries of all target compounds were 91.8% – 103.6%. The decision limits were from 109.0 to 119.8 μg/kg and detection capability varied within the range of 122.2 to 137.6 μg/kg, depending on the analyte.

Open access

Anna Gajda, Andrzej Posyniak, Andrzej Bober, Tomasz Błądek and Jan Żmudzki

Summary

A liquid chromatography method with UV detection for determination of oxytetracycline (OTC) in honey has been developed. The samples were extracted with the solution of oxalic acid. The clean-up procedure was performed by solid phase extraction (SPE) using polymeric Strata X and carboxylic acid cartridges. Chromatographic separation was carried out on the Luna C8 analytical column with mobile phase consisting of acetonitrile-0.02 M oxalic acid. The method has been successfully validated according to the requirements of the European Decision 2002/657/EC and this method is used in routine control of oxytetracycline in honey samples. The limit of detection (LOD) and limit of quantification (LOQ) of the presented method were 10 and 12.5 μg/kg, respectively. The developed method has also been verified in quantitative determination of oxytetracycline residues in honey after experimental treatment with this product in bee colonies.

Open access

Tomasz Błądek, Andrzej Posyniak, Anna Gajda, Małgorzata Gbylik and Jan Żmudzki

Abstract

A liquid chromatographic method coupled with tandem mass spectrometry for determination of residues of β-lactams, macrolides, tetracyclines, quinolones, sulfonamides, and lincosamides in eggs has been described. Analytes were isolated from egg samples by solvent extraction method and extracts were cleaned by filtration on OASIS HLB cartridges. The whole procedure was validated according to European Commission Decision 2002/657/EC. The recovery ranged between 86% and 110%. The repeatability was below 16% and within-laboratory reproducibility was lower than 20%. The method was successfully applied in the official control of antibacterial compounds residue in Poland.

Open access

Tomasz Śniegocki, Jan Żmudzki, Andrzej Posyniak and Bartosz Sell

Abstract

An in-house reference material of chloramphenicol (CAP) in pigs muscle was prepared from the chloramphenicol treated animals. The incurred muscle material was diluted by mixing with blank muscle sample. The concentration of CAP at the level 0.33 μg kg−1 was reached. For the homogeneity study, 10 random samples were analysed and the results were interpreted by Cochran’s test and the sufficient homogeneity test. Additionally, the samples were tested for their stability according to the following scheme: 1, 7, 14, 28, 56, 84, and 112 d. It was confirmed that an appropriate homogeneity and stability of the produced in-house reference material was obtained.

Open access

Kamila Mitrowska, Maja Antczak and Andrzej Posyniak

Abstract

A multiresidue method for the determination of seven nitroimidazoles and their hydroxy metabolites in milk was developed. Milk samples were extracted with acetonitrile and cleaned up on strong cation-exchange solid phase extraction cartridges. Evaporated to dryness first, the extracts obtained were then reconstituted in 0.1% formic acid and injected onto a liquid chromatography-tandem mass spectrometer (LC-MS/MS). The separation of analytes was achieved on gradient mode using a C18 column and a mobile phase consisting of 0.1% formic acid in acetonitrile and 0.1% formic acid in water. Multiple reaction monitoring mode was set for the MS/MS with positive electrospray ionisation. For quantification, the isotope dilution method was used with isotopically labeled analogues of the target analytes. The method was evaluated entirely in accordance with EU Commission Decision 2002/657/EC and all validation criteria were in the required ranges. The method can easily detect and confirm metronidazole, dimetridazole, ronidazole, ipronidazole, and their hydroxy metabolites below the recommended concentration level of 3 μg/kg. The decision limits and detection capabilities ranged from 0.11 μg/kg to 0.22 μg/kg and from 0.19 μg/kg to 0.37 μg/kg respectively. The overall recoveries were between 96.6% and 105.2% with a good coefficient of variation, less than 8.7% under within-laboratory reproducibility conditions.

Open access

Małgorzata Gbylik, Andrzej Posyniak and Anna Gajda

Abstract

An HPLC method with fluorescence detection (HPLC-FLD) was developed for the simultaneous quantitative determination of enrofloxacin, ciprofloksacin, sarafloxacin, and difloxacin in feed. The samples were extracted with 0.25% formic acid in ultrasonic bath and purified by solid phase extraction (SPE) on Strata-X cartridges. The samples were analysed on Luna C8 liquid chromatography column with gradient programme by acetonitrile and 0.025 M phosphoric acid with 0.0025 M sodium 1- heptanesulfonate monohydrate. The method was successfully validated according to the requirements of the European Decision 2002/657/EC. Recoveries of the components from spiked feed samples ranged from 55%-70%. Repeatability was <7%. The method presented here proved to be efficient, rapid, and a selective approach for determination of fluoroquinolones in feed.

Open access

Barbara Woźniak, Iwona Matraszek-Żuchowska, Sebastian Witek and Andrzej Posyniak

Abstract

Introduction: In the European Union the use of steroid growth promoters is prohibited under Council Directive 96/22/EC. For effective control of illegal use of natural steroids, highly sensitive analytical methods are required, because sex hormones can be present in very low concentrations in biological samples. The aim of the study was to develop a confirmatory method for the detection of testosterone in bovine serum at ppt level.

Material and Methods: 17β-testosterone and internal standards of 17β-testosterone-d2 were extracted from serum samples with a mixture of tert-butyl methyl ether/petroleum ether and were directly analysed by an LC/MS/MS on QTRAP 5500 instrument with a TurboIon-Spray source operating in a positive ionisation mode. Chromatographic separation was achieved on the analytical column Inertsil® ODS-3 with an isocratic elution using mobile phase consisting of acetonitrile, methanol, and water. Method validation has been carried out in accordance with the Commission Decision 2002/657/EC.

Results: The method was characterised by good recovery (82%) and precision (R.S.D 17 %). Decision limit (CCα) and detection capability (CCβ) was 0.05 μg L−1 and 0.09 μg L−1 respectively. The method met the criteria set out in Commission Decision 2002/657/EC for the purpose of confirmation in terms of retention time and ion ratio in the whole range of its application.

Conclusions: The developed method is specific and sensitive, suitable for measuring the natural level of testosterone in blood of cattle and for use in routine control programme for the detection of this hormone in bovine serum.

Open access

Tomasz Śniegocki, Małgorzata Gbylik-Sikorska and Andrzej Posyniak

Abstract

Introduction: The main problem in determination of chloramphenicol in food of animal origin is a large number of matrices. The main target of this study was to create a method for determination and confirmation of chloramphenicol in products and food of animal origin. Material and Methods: Each 5 g matrix sample was mixed with 5 mL of water and 10 mL of acetonitrile/ethyl acetate, homogenised, and centrifuged. The organic layer was evaporated and redissolved in 6 mL of 4% NaCl. The extract was cleaned up by SPE technique. Chloramphenicol was analysed by LC-MS/MS in electrospray mode. Results: The procedure was validated according to the Commission Decision No. 2002/657/EC. The apparent recoveries were in the range of 92.1% to 107.1% with a repeatability less than 11.0% (4.4%-11.0%) and within-laboratory reproducibility below 13.6% (4.7%-13.6%). Conclusion: The method was successfully validated and proved to be efficient, precise, and useful for quantification of chloramphenicol in more than 20 different matrices.

Open access

Anna Gajda, Andrzej Posyniak and Grzegorz Tomczyk

Abstract

For the purpose of quantitative determination of doxycycline (DC) residues in tissues, a sensitive liquid chromatography - tandem mass spectrometry (LC-MS/MS) method was developed. The method was used to determine DC residues in chicken tissues (breast and thigh muscle, liver and kidney) after oral administration with drinking water to five-weak-old broiler chickens. The DC was administered for five consecutive days at a therapeutic dose of 10 mg/kg b.w. once a day. The tissues were collected after 6 h, 24 h, 7 d, and 8 d. The method was validated and the decision limit was established for muscle - 109.2 μg/kg, for liver - 326.1 μg/kg, and for kidney - 634.0 μg/kg. The detection limit was 2 μg/kg and the limit of quantification was 5 μg/kg. In a short period after ceasing the treatment, the detected concentrations of DC were much higher than the established maximum residue limit values. The highest residue concentrations of DC were observed in the kidney, followed by the liver and muscle. The lowest concentration of DC was determined in tight muscle.

Open access

Barbara Woźniak, Sebastian Witek, Iwona Matraszek-Żuchowska, Alicja Kłopot and Andrzej Posyniak

Abstract

Introduction: The present study is a comprehensive overview of the natural occurrence of 17β-oestradiol and testosterone in serum of cattle in Poland. Material and Methods: The serum samples (n = 826) were collected from cattle within five years. The samples were examined for the presence of oestradiol and testosterone using ELISA or gas chromatography with mass spectrometry. Results: In 98 samples (24%) 17β-oestradiol was detected above decision limits of applied methods, including five samples over the recommended concentration of 0.1 μg L-1. Of the serum samples taken from cows (≤18 months of age), 95 and 99 percentiles of the animals had 17β-oestradiol concentration below 0.027 and 0.086 μg L-1 and of samples from cows over 18 months of age - below 0.059 and 0.125 μg L-1 respectively. Calculated values for bulls (≤18 months of age) were 0.025 and 0.034 μg L-1 and for the animals older than 18 months of age - 0.035 and 0.041 μg L-1. The natural presence of testosterone was detected in 201 serum samples (48.7%). According to the obtained data, 95% and 99% of cows (≤18 months of age) serum samples had testosterone concentration below 0.05 and 0.23 μg L-1 and the animals over 18 months of age - 0.30 and 0.49 μg L-1, respectively. For bulls these values did not depend on the age of the animals and were in the ranges of 5 - 6.3 μg L-1 (95%) and 11.4 - 12.1 μg L-1 (99%). Conclusion: Our study showed that the threshold values for these hormones in plasma of cattle designated years ago are correct, but they need to be supplemented for animals older than 18 months.