A simple, sensitive, reliable method was developed for the simultaneous determination of organochlorine and pyrethriod pesticide residues in Chinese patent medicines Six ingredient rehmannia pills and Xiaoyao pills. These pesticides were extracted by ethyl acetate. The extraction time and volume of ethyl acetate were optimized. Cleanup of extracts was performed with dispersive-solid phase extraction using graphitized carbon black as the sorbent. The determination of pesticides in the final extracts was carried out by gas chromatography–tandem mass spectrometry in multiple reaction monitoring mode (GC-MS/MS, MRM). The linearity of the calibration curves is good in matrix-matched standard and yields the coefficients of determination (R2) ≥0.99 for all of the target analytes. Under optimized conditions, the average recoveries (five replicates) for most pesticides range from 75.5% to 114.6%, and RSDs are less than 10.0%. The LODs of 18 pesticides in Six ingredient rehmannia pill and Xiaoyao pills are in the range of 0.01–8.82 μg kg?1. The developed method meets the requirements of pesticide residue analysis and could be effectively used for routine analysis of the organochlorine and pyrethriod pesticide residues in Six ingredient rehmannia pills and Xiaoyao pills. 相似文献
Heavy metal concentration in soil was investigated at three sites with different topography (cut slope, flat and embankment) within the vicinity of Chengdu-Kunming railway in Sichuan, China. Surface soil was sampled at certain distances from the track at each site and was analyzed for Cu, Mn, Pb, Zn, Cd by atomic absorption spectrometry. Cu, Cd and Zn concentrations in some soil exceeded the thresholds for non-polluted soil following the soil quality standard set by the State Environmental Protection Agency of China. Compared to local background values, the highest enrichment factor values of Cu, Mn, Zn and Cd were 2.7, 3.4, 3.7 and 7.7, respectively, indicating a moderate or significant enrichment of these metals in soil closest to the railway. Pb showed little accumulation with the EF values generally nearer 1 at the chosen sites. Topography profile was found to influence metal levels and distribution in soil alongside railway. At the cut slope site, Mn, Zn, Cd showed the highest concentrations and the smallest dispersion distance of 2 m, while Cu showed further dispersion distance of 25 m due to a main Cu emission source, the head-over traction cable, being located higher than any other metal emission source (wheels and tracks). Heavy metal concentrations decreased conversely as compared to distance from the track, peak values occurring at locations closest to the tracks, whilst embankment site soil Cd concentrations peaked at distances of 25 m. Significant correlation was found amongst Mn, Cu, Zn and Cd, which indicates that these metals have the same anthropogenic origin there. Organic matter content had no significant correlation to the elements Mn, Cu and Zn, which implies relatively high mobility to those metals. 相似文献
This study aimed at revealing the levels of polybrominated diphenyl ethers (PBDEs) in breast milk from primipara in Shenzhen (China), and estimating daily intake of PBDEs for breast-fed infants. Concentrations of 7 PBDEs were measured in 60 breast milk samples by isotope dilution HRGC/HRMS (high-resolution gas chromatography/high-resolution mass spectrometry). The intake of PBDEs for breast-fed infants was estimated based on the infant's daily milk consumption. The range of total concentration of 7 PBDEs congeners in samples was 2.6-188.6 ng g(-1) lipid (mean: 14.8 ng g(-1) lipid; median: 7.2 ng g(-1) lipid). The mean estimated daily intake of PBDEs by breast-fed infants ranged from 9.9 to 335.9 ng kg(-1) body weight (bw) per day (mean: 52.5 ng kg(-1) bw per day; median: 28.6 ng kg(-1) bw per day). The levels of PBDEs body burden in the recruited mothers of Shenzhen were higher than those reported previously for the general population from other areas in China. No significant correlations were found between the body burden of PBDEs and the mothers' age, pre-pregnancy BMI, dietary habits, duration of residence in Shenzhen, weight and length of the newborns. BDE-47 and BDE-153 were major PBDE congeners in milk samples, while the congeners of BDE-183 and BDE-28 were also high in Shenzhen. The situation may be attributed to the special economic pattern including electronic production in Shenzhen in the past three decades. Continuous surveillance on PBDEs levels in human milk is needed in order to accurately evaluate the environmental impact of PBDEs to human health in Shenzhen. 相似文献
Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and microelectrode technology were employed to evaluate the Nitrous oxide (N2O) production in biological aerated filters (BAFs) under varied dissolved oxygen (DO) concentrations during treating wastewater under laboratory scale. The average yield of gasous N2O showed more than 4-fold increase when the DO levels were reduced from 6.0 to 2.0 mg?L–1, indicating that low DO may drive N2O generation. PCR-DGGE results revealed that Nitratifractor salsuginis were dominant and may be responsible for N2O emission from the BAFs system. While at a low DO concentration (2.0 mg?L–1), Flavobacterium urocaniciphilum might play a role. When DO concentration was the limiting factor (reduced from 6.0 to 2.0 mg?L–1) for nitrification, it reduced NO2--N oxidation as well as the total nitrification. The data from this study contribute to explain how N2O production changes in response to DO concentration, and may be helpful for reduction of N2O through regulation of DO levels.