ABSTRACT
Objective@#To establish a liquid chromatography-tandem mass spectrometry (LC/MS/MS) method for the determination of microcystin-LR (MC-LR) in drinking water, investigate its removal efficiency during tap water advanced treatment process and analyze its degradation products in the tap water.@*Methods@#Two parallel water samples were collected from each point of tap water advanced treatment process in September 2015, November 2015 and January 2016, respectively, and treated by mixing, filtration, concentration, elution, nitrogen blow and re-dissolvement. The samples were analyzed by LC/MS/MS to determine the MC-LR concentration and its removal efficiency during treatment process. The combination of actual water enrichment (including source water enrichment of 50 times and 1 500 times concentrated, finished water enrichment of 50 times and 2 500 times concentrated) and laboratory simulated water (including the mixture of MC-LR and liquid chlorine in the mass ratio of 1∶10, 1∶20, 1∶100 and 1∶1 000, respectively) were used to qualitative analyze the MC-LR degradation products by Orbitrap mass spectrometry.@*Results@#The linearity of MC-LR ranged from 2 to 200 μg/L with the detection limit of 0.007 9 μg/L and the limit of quantification of 0.026 3 μg/L. The recovery rate of MC-LR from different contration in drinking water were from 94.88%-101.47%. The intra-day precision was 2.51%-7.93% and the intra-day precision was 3.24%-8.41%. The average concentration of MC-LR in source water was (0.631±0.262) μg/L, 94.0% of which can be removed by ozone exposure while the concentrate was (0.038±0.016) μg/L, biological pre-treatment and chlorination. The remaining can hardly be removed by sand filtration, ozone exposure, activated carbon, ultrafiltration and other processes. The MC-LR average concentration in the finished water maintained at about (0.036±0.016) μg/L. Degradation products including hydroxy-microcystin, methyl-hydroxy-microcystin, methyl-microcystin were identified in the laboratory simulated water of the mixture of MC-LR and liquid chlorine in the mass ratio of 1∶10.@*Conclusion@#The established MC-LR detection method can be well applied to the monitoring of MC-LR in drinking water due to its simple pre-treatment process and good methodological validation parameters. The degradation products of treatment processes was different.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the mortality rates of hepatocellular carcinoma (HCC) in Nantong,China from 1999 to 2011, in order to uncover dynamic trends and provide reasoned advice on intervention strategies to decrease HCC incidence and mortality in Nantong in the future.</p><p><b>METHODS</b>Versions 10 and 9 of the WHO International Classification of Diseases (ICD-10 and ICD-9) were used to determine the number of HCC deaths in Nantong,China for the study's range of years. Thex2 test was applied to compare the HCC mortality rates according to sex and age. The Grey system GM(1,1) model was used to predict the next-5-year HCC mortality for Nantong.</p><p><b>RESULTS</b>Analysis of the standardized mortality in Nantong showed a slight decreasing trend from 1999 to 2011 (x2=57 545.98, P less than 0.001),with males showing a steeper decrease than females. The total mortality of HCC during these years was 53.41 per 100,000 people,with mortality among males being significantly higher than that among females (80.81 per 100,000 people vs. 26.94 per 100,000 people; x2=13 625.42, P less than 0.001). In general, HCC mortality increased with increase in age (general trend:x2=57 545.98, P less than 0.001; male trend: x2=39 878.8, P less than 0.001; female trend: x2=20 105.3, P less than 0.001). However,HCC mortality increased significantly in women after the age of 40 and in men after the age of 35. The GM(1,1) equation was: Yt=-1265.28e(-0.0375t)+1315.5, which predicted that the HCC mortality will decrease to 25.56 per 100,000 people in 2016.</p><p><b>CONCLUSION</b>Although HCC mortality generally decreased from 1999 to 2011, the rate remained high. Public health intervention strategies may be more effective if they focus on males over the age of 35 and females over the age of 40.</p>