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@#Objective - To optimize the extraction and quantification methods for the determination of S phenylmercapturic acid - Methods (SPMA) in urine with performance liquid chromatography mass spectrometry. The urine was hydrolyzed with 50.0% sulfuric acid. The hydrolysate was purified by solid phase extraction column. Purified samples were separated by C18 chromatographic column and detected by tandem mass spectrometry. The isotope labeled SPMA was used as the internal Results - standard. The internal standard curve was used for quantification. The linear range of SPMA was 0.50 50.00 μg/L with the correlation coefficient of 0.999 8. The detection limit and the lower limit of quantification were 0.05 and 0.17 μg/L, - - - - respectively. The recovery rate was 97.0% 102.0%. The within run and between run relative standard deviation were 0.6% 1.0% - and 1.7% 6.5%, respectively. The mass concentration of urinary SPMA in the occupational benzene exposure group was - vs P higher than the non occupational benzene exposure group by this method (median: 2.81 0.28 μg/g creatinine, <0.05). Conclusion Compared to the national standard method, this optimized method of solid phase extraction and internal standard for quantification eliminates the matrix effect. This method is accurate and precise, and is suitable for the determination of SPMA acid in urine.
RESUMO
Abstract Purpose: To investigate the impact of different hypoxia reoxygenation (HR) times on autophagy of rat cardiomyocytes (H9C2). Methods: Rat cardiomyocytes were randomly divided into normal control group (group A), hypoxia group (group B), 2 h HR group (group C), 12 h HR group (group D), and 24 h HR group (group E). LC3 II/LC3 I was determined via western blotting, and cell viabilities of cardiomyocytes were measured using methyl thiazolyl tetrazolium (MTT) assay. Results: Cell viabilities in HR model groups were significantly lower than those of group A (P<0.05). LC3 II/LC3 I levels in groups B to D were significantly higher than those of group A (P<0.05), and group D showed the highest LC3 II/LC3 I levels. Cell viabilities in groups B to D were significantly lower than those of group A (P<0.05), with group D showing the lowest cell viabilities (P<0.05). Conclusions: Hypoxia can induce autophagy in rat cardiomyocytes, which can be further activated by reoxygenation; most notable after 12 h. Hypoxia-induced cell injury can be aggravated by reoxygenation. The lowest cell viability was observed at 12 h after reoxygenation; however, cell viability can be recovered after 24 h.