Search Results

1 - 10 of 23 items

  • Author: Jan Żmudzki x
Clear All Modify Search

Abstract

The present study assessed the sensitivity of immature hamster uterotrophic assay to reference oestrogen agonists/antagonists in order to develop a sensitive model for evaluation of endocrine-active compounds in diets. After performing a baseline for control animals, the sensitivity of immature females (postnatal day 18) to reference compounds was evaluated in a three-day uterotrophic assay. The absolute and adjusted dry uterine weights, fold induction over control for absolute wet uterine weight, and wet uterine weight/body weight ratio (%) were used as endpoints. The significantly active doses for reference oestrogens were as follows: 0.6 μg/kg for 17α-ethinyloestradiol (s.c.); 1 μg/kg/day (s.c.) and 40 μg/kg (p.o.) for diethylstilboestrol; 40 mg/kg (s.c.) and 160 mg/kg (p.o.) for bisphenol A. Co-treatment with tamoxifen at a dose of 1 mg/kg significantly antagonised the uterotrophic effect induced by 1 μg/kg 17α-ethinyloestradiol, and showed the attenuated proliferative effect in histopathological examination. We found immature hamster uterotrophic assay as a sensitive model that could be a good alternative to the rat assay.

Abstract

This paper describes the quantitative method of determination of chosen substances from resorcylic acid lactones group: zeranol, taleranol, α-zearalenol, β-zearalenol, and zearalanone in bovine muscle tissue. The presented method is based on double diethyl ether liquid-liquid extraction (LLE), solid phase extraction (SPE) clean up, and gas chromatography mass spectrometry (GC-MS) analysis. The residues were derivatised with a mixture of N-methyl-N-trimethylsilyltrifluoroacetamide, ammonium iodide, and DL-dithiothreitol (1,000:2:5, v/w/w). The GC-MS apparatus was operated in positive electron ionisation mode. The method was validated according to the European Union performance criteria pointed in Decision Commission 2002/657/EC. The average recoveries of all analytes at 1 μg kg-1 level were located between 83.7% and 94.5% values with the coefficients of variation values <25%. The decision limits (CCα) and detection capabilities (CCβ) for all analytes ranged from 0.58 to 0.82 μg kg-1 and from 0.64 to 0.94 μg kg-1, respectively. The procedure has been accredited and is used as a screening and confirmatory method in control of hormone residues in animal tissues.

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.

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.

Abstract

Natural occurrence of thiouracil in bovine and swine urine in Poland was investigated. Under the national residue control programme, 537 urine samples were tested. In 77 samples (14.3%) thiouracil was detected above decision limit CCα (0.91 μg L-1), including eight samples over the recommended concentration of 10 μg L-1. Of the bovine urine samples, 95 and 99 percentiles have thiouracil concentration below 4.50 and 14.85 μg L-1 ,and of porcine samples below 2.35 and 6.80 μg L-1, respectively.

Abstract

A sensitive and reliable method has been developed and validated to determine residues of abamectin, doramectin, eprinomectin, ivermectin, and moxidectin in bovine milk. Isolation of the analytes from milk was performed with the use of liquidliquid extraction with acetonitrile in the presence of sodium chloride. The extract was defatted with hexane and cleaned up using solid phase extraction (C8 cartridge) after forming ion pairs with triethylamine. The analytes were derivatized with N, Ndimethylformamide, acetic acid anhydride, and N-methylimidazole (100°C, 90 min). The derivatives were determined by reverse phase liquid chromatography with fluorescence detection (excitation and emission wavelength 365 nm and 475 nm, respectively). Recoveries of the lactones from milk samples fortified at 10-30 μg kg-1 ranged from 52% to 80% with intra-laboratory reproducibility (CV) of 12.7%-22.8%. The critical concentrations (decision limit, CCα and detection capability, CCβ) were in accordance with target limits. The method has been verified in the proficiency studies by EURL/CVL Berlin (all z-scores in the range of ±2). The method was transferred to routine laboratories, verified in inter-laboratory comparison and successfully applied in the National Residue Control Plan.

Abstract

Samples for analysis were collected from 10 areas, including the major Polish rivers and lakes, with different sources of environmental pollution (industrial, municipal, and farming). The materials was taken from the lakes of Mazury, located in a non-industrialised region, from the Brda River, an area impacted by pig farms, from the lakes of Lipczyno Wielkie/Pomerania, from the Wkra River, an area impacted by poultry farms, from the Dunajec River at the Roznowski Reservoir, from the Vistula River at Cracow and Warsaw, from the Odra River at Wroclaw and the Warta River estuary, and also from Rybnik Power Station Reservoir. Concentrations of Pb, Cd, Hg, and As were analysed in 397 fish muscle and 128 sediment samples using an atomic absorption spectrometry technique. The analytical procedures were covered by a quality assurance programme. It was demonstrated that the average concentrations of lead, cadmium, and arsenic in fish were in the low hundredths and thousandths of a mg/kg and never exceeded permitted limits established for food. Higher values of these elements were found in fish from bodies of water located in the zone of influence of large urban agglomerations, especially the Cracow region. High concentrations of lead and cadmium were also found in Vistula River sediments near Cracow, where the maximum values were 134.10 mg/kg and 21.24 mg/kg dry weight for lead and cadmium respectively. The average concentration of mercury in a predatory fish muscle (0.179 mg/kg) was almost twice as high as in the omnivorous fish (0.103 mg/kg). Only a single fish sample exceeded the maximum limit for this metal (0.50 mg/kg) and did not present a risk to consumers’ health.

Abstract

The aim of the study was to test and compare the cytotoxic potential of two synthetic oestrogens: diethylstilboestrol (DES) and ethinyloestradiol (EE2) and two androgens: testosterone propionate (TP) and trenbolone (TREN) on two cell lines. The fibroblast cell line Balb/c 3T3 and the hepatoma cell line HepG2 were selected. To get more insight into the mode of toxic action, four methods were used, which evaluated different biochemical endpoints: mitochondrial activity (3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide reduction assay), lysosomal activity (neutral red uptake assay), total protein content, and lactate dehydrogenase release. Cytotoxicity was assessed after 24, 48, and 72 h exposure to eight concentrations ranging from 0.78 to 100 μg/mL. Concentration- and time- dependent effects were observed. Depending on the line and assay used, half maximal effective concentration after 72 h (EC50-72h) values ranged as follows: DES 1-13.7 μg/mL (Balb/c 3T3) and 3.7-5.2 μg/mL (HepG2); EE2 2.1-14.3 μg/mL (Balb/c 3T3) and 1.8-7.8 μg/mL (HepG2); TP-14.9-17.5 μg/mL (Balb/c 3T3), and 63.9- 100 μg/mL (HepG2); and TREN 11.3-31.4 μg/mL (Balb/c 3T3) and 12.5-59.4 μg/mL (HepG2). The results revealed that oestrogens were more toxic than androgens and the most affected endpoint was mitochondrial activity. In contrast to oestrogens, for which EC50-72h values were similar in both lines and by all assays used, Balb/c 3T3 cells were more sensitive than HepG2 cells to TP.

Abstract

A simple and sensitive gas chromatography method was developed to determine a group of oestrogens in surface water. In the first stage of analysis, enzymatic hydrolysis of oestrogen metabolites with glucuronidase AS-HP was performed. Free compounds were extracted from 200 mL of water sample on C18 SPE column (6 mL, 1000 mg). The evaporated extract was subjected to derivatisation with a mixture of MSTFA/NH4I/DTT (1000:2:5, v/w/w). The separation of the analytes on HP-5ms capillary column was conducted. The method was validated according to the Commission Decision 2002/657/EC. Recovery in spiked samples ranged from 90% to 120 % with standard deviation lower than 30% for all examined compounds. The decision limit and detection capability of five oestrogens were in the range of 0.3-0.6 ng L-1 and 0.5-0.9 ng L-1, respectively. Nineteen water samples collected from different sites of several Polish rivers and lakes were tested for the presence of oestrogens. Some target compounds such as 17α-oestradiol, 17β-oestradiol, oestrone, oestriol, and 17α-ethynyloestradiol were found in trace amounts in the analysed samples. The highest concentration observed for oestradiol reached 23 ng L-1.

Abstract

A rapid liquid chromatography tandem mass spectrometry method was developed and validated to detect and confirm five thyreostatic drugs: tapazole, thiouracil, methylthiouracil, propylthiouracil, and phenylthiouracil in animal feeding stuff samples. Thyreostats were extracted from feed with methanol, and then degreasing of the extract with petroleum ether was performed, followed by the derivatisation of the compounds with 3-iodobenzylbromide in basic medium (pH 8.0). The derivatives were extracted with diethyl ether and analysed by gradient elution on a Poroshell 120-EC C18 column with triple quadrupole MS detection with turbo spray source in positive ionisation mode. The method was validated in accordance with the Commission Decision 2002/657/EC. For validation level of 10 ļig kg-1, the recovery ranged from 82% to 97.5% for all examined compounds. The repeatability and reproducibility did not exceed the limit of 20% for all analytes. The linearity was good for all thyreostats in the whole range of tested concentrations, as proved by the correlation coefficients greater than 0.99. The decision limits (CCa) ranged from 1.63 ļig kg-1 to 3.95 ļig kg-1, whereas the detection capabilities (CCß) ranged from 2.74 ļig kg-1 to 6.73 ļig kg-1. The developed analysis is sensitive and robust, and therefore useful for quantification and confirmation of thyreostats in residue control programme.