ABSTRACT
Objective To establish a reliable pretreatment method for the detection of mequindox and its metabolite in pork luncheon meat by ultra-performance liquid chromatography/triple qudrupole tandem mass spectrometry. Methods Samples were extracted with ethyl acetate, and the results of purification and enrichment by PAX and PEP solid-phase extraction columns were analyzed. Acetonitrile/methanol (3:11) - 0.1% formic acid water was used as the mobile phase, and Shimadzu Inertsil ODS-3-column (3µm, 2.1 × 100mm) chromatographic columns were used for qualitative and quantitative analysis using the multi-reaction detection positive ion mode. Results The results showed that PEP cartridge had good recovery rate. The detection limit of mequindox was 0.10µg/kg, and limit of quantitation was 0.30µg/kg. The average recoveries for spiked levels of 0.33, 0.83, and 1.65µg/kg were 127%, 72.0%, and 60.1%, respectively. The detection limit of 2-quinoxalinecarboxylic acid was 0.10µg/kg, and limit of quantitation was 0.40µg/kg. The average recoveries for spiked levels of 0.42, 1.05, and 2.1µg/kg were 125%, 99.0%, and 60.9%, respectively. Conclusion This method is suitable for the determination of mequindox and its metabolite 2-quinoxalinecarboxylic acid in luncheon meat.
ABSTRACT
Objective To study the microstructural and ultrastructural changes of the epididymis of experimental varicocele in adolescent rats and it's role in infertility resulting from varicocele. Methods A varicocele model was performed in adolescent Sprague Dawley rats by partially ligating the left renal vein,the different segments of the epididymides of the rats were prepared for light and electron microscopy,the microstructure and ultrastructure of the epididymis were studied. Results There were lesions of different degree and segment specific changes in the epididymis with varicocele.Light microscopically,the main changes were interstitial vascular hyperemia,lymphocytes infiltration,sperm granuloma developed in the interstitial;The structure of the columnar epithelia was anomalies,epithelial cells degeneration,even the vacuoles appeared in the epithelial cells.The number of halo and clear cells increased.Inside the cavity of the duct,there were shedding cells,macrophage,deformed sperms and residual bodies.Electron microscopically,numerous large lysosomes,the residual bodies,the defected main cellular organelles(e.g. the endoplasmic reticulum,the mitochondrion and the Golgi complex etc.)and even large clear vacuoles were presented in the cytoplasm of principal cells.Clear cells were filled with lysosomes that made them frequently bulging into the lumen.The microvilli of the columnar epithelia were sparse and showed local defects.The thickness of the basal membrane increased.Conclusion\ The experimental varicocele in adolescent rats lead to microstructure and ultrastructure lesions in the epididymis,which may be another important reason of infertility resulting from varicocele.\;[