Determination of stilbenes and resorcylic acid lactones in bovine, porcine and poultry muscle tissue by liquid chromatography-negative ion electrospray mass spectrometry and QuEChERS for sample preparation.

Liquid chromatography tandem mass spectrometry method was developed and validated to confirm of resorcylic acid lactones: zeranol, taleranol, zearalanone, zearalenone, α and ß-zearalenol and stilbenes in muscle tissue. The compounds were analyzed by LC-MS/MS QTrap 5500 apparatus in negative ionization mode. Chromatographic separation on Poroshell 120-EC C18 (150mm×2.1mm, 2.7µm) column was achieved at 45°C using isocratic elution of mobile phase - methanol/water (65:35, v/v). For the treatment of tissue samples prior to analysis, QuEChERS method was applied based on the extraction of analytes from muscle samples with ethyl acetate, separation of the aqueous and organic phases with application of magnesium sulphate and sodium acetate, the purification of the extract obtained by dispersive SPE with the use of sorbent C18, PSA and magnesium sulphate. The method was validated in accordance with the Commission Decision 2002/657/EC. Good recoveries were obtained (from 83% to 115%) as well as acceptable within-lab reproducibility (<22%). The values of the decision limit CCα and the detection capability CCß for individual compounds are found to be below the recommended concentration set at 1µgkg(-1) and not exceed 0.23µgkg(-1) and 0.39µgkg(-1), respectively. The elaborated method meets the criteria for confirmatory methods and is used in the official control of hormones.

Liquid chromatography tandem mass spectrometry with ion trap and triple quadrupole analyzers for determination of thyreostatic drugs in urine and muscle tissue.

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 CCß 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.