气相色谱法测定水中三氯杀螨醇和除拟虫菊酯的方法验证

目的：验证气相色谱法测定水中三氯杀螨醇和7种除拟虫菊酯。方法水样中的微量三氯杀螨醇和除拟虫菊酯经液液萃取后，利用 HP-5毛细管柱，在程序升温条件下进行 GC 分析，以保留时间定性，外标法定量。结果质量浓度0.156～5.00μg／mL 范围内线性关系良好，相关系数 r ＞0.9960，回收率范围为81.9％～106.7％，RSD 为0.5％～4.8％。采用本法对10件水样进行检测，均未检出三氯杀螨醇和7种除拟虫菊酯。结论气相色谱法操作简便，测定结果可靠，方法稳定性和重复性较好，可以满足生活饮用水中三氯杀螨醇和7种除拟虫菊酯测定要求。

液相色谱法测定小麦粉中拟虫菊酯类农药残留

建立了高效液相色谱法(HPLC)同时测定小麦粉中7种拟虫菊酯类农药残留的方法。样品经乙腈和丙酮(V∶V/90∶10)的混合溶液提取,固相萃取柱净化,采用光化学衍生技术结合荧光检测器测定,外标法定量。7种拟虫菊酯类农药得到很好的分离,回收率为84%～118%,相对标准偏差(RSD)为2.81%～6.44%,检出限为0.002～0.010 mg/kg。实验结果表明,该方法简单、快速、重现性好,满足小麦粉中拟虫菊酯类农药残留测定要求,适用于一般实验室开展日常检测。

HPLC法测定2－（4－氯苯基）－3－甲基丁酸的光学纯度

利用Ｓｉ－５色谱柱，石油醚／乙醇（７：３体积）流动相，检测波长３００纳米，成功地分离了２－（４－氯苯基）－３－甲基丁酸与（Ｓ）－α－苯乙胺生成的一对非对映体。分别测其线性关系及响应因子，由此计算出２－（４－氟苯基）－３－甲基丁酸的光学纯度。准确度为９９．２～１０１．０％，平均标准偏差为０．０６６％。

Determination of 10 Pyrethroids Pesticide Residues in Rice by GC-MS-MS

[Objective] A method was developed for the determination of 10 pyrethroids pesticide residues in rice by GC-MS-MS. [Method] Pyrethroids were extracted with acetonitrile, followed by a salting-out step with anhydrous magnesium sulfate and sodium chloride, cleaned up by florisil solid phase extraction （SPE） cartridge, and determined by multiple reaction monitoring mode. [Result] The method showed good linearity over the range of 0.010-0.500 mg/L for 10 pyrethroid pesticide with correlation coefficients over 0.99. The detection limits were 0.005 -0.010 mg/kg. The method was validated by analyzing samples spiked with 0.05, 0.10, 0.20 mg/kg of 10 pyrethroid pesticides, respectively. The average recoveries in rice ranged from 75.0-115.5%, and the relative standard deviations （RSD） were between 3.9%-6.9%. [Conclusion] The method is easy, accurate and reliable, which can meet the requirement for the simultaneous determination and confirmation of pyrethroid pesticide residues in rice.

Translocation of Pesticide Residues in Tomato, Mango and Pineapple Fruits

Pesticide residues in fruit and vegetables have become a major concern associated with chemical food safety issues. Translocation of pesticides in tomato, mango and pineapple fruits in locally produced samples was investigated using gas chromatography/mass spectrophotometer （GC/MS） procedures. Samples were fractionated with respect to distance from the skin to the core and prepared for analysis. Results showed that organochlorine, organophosphate and synthetic pyrethroid residues were translocated in all fruit samples analyzed. With respect to tomato fractions, the peels retained more residues compared to the pulp and the central core. In the chemical species, organochlorines were retained more in the peels of tomato than the other fractions of the fruit. More organophosphate and organochlorine residues were detected in pineapple peels compared to the pulp. Synthetic pyrethroid residues were evenly distributed in the pineapple fruit. In mangoes, the pulp retained more chemical residues than other fractions of the fruit. More organochlorine residues were retained in the pulp of mango than in the other fractions of the fruit. Synthetic pyrethroid residues were evenly distributed throughout the mango fruit. All the chemical species identified were translocatable across the fractional parts of all the fruits. There were significant differences in translocation and residue accumulation of pesticides among the fractional parts of all samples.

Marine bacterium strain screening and pyrethroid insecticide-degrading efficiency analysis

A pyrethroid insecticide-degrading bacterium, strain HS-24, was isolated from an offshore seawater environment. The strain, which can degrade cypermethrin （CYP） and deltamethrin （DEL）, was identified as Methylophaga sp. The optimal culture and degradation conditions for CYP and DEL by strain HS-24 is pH 7 at 28℃. Under optimum culture conditions, strain HS-24 exhibited a broad degradation concentration range of 100, 200, 400, 600, and 800 mg/L for CYP and DEL. The metabolic intermediates were analyzed by NMR, which provided strong evidence that CYP and DEL removal occurred mainly because of a biological process. The toxicity of the degradation products of strain HS-24 was studied simultaneously by measuring the light output of the luminescence bacterium. This demonstrated that the biodegradation ability of strain HS-24 significantly decreased the toxicity of CYP- and DEL-contaminated aquaculture seawater. Finally, the findings of this paper indicate that strain HS-24 is thus revealed as a biological agent for the remediation of marine aquatic environments.

Comparative Toxicity of Selected Insecticides to Phytoplasma Transmitted Leafhopper Cicadulina bipunctata （Melichar）

Leafhopper Cicadulina bipunctata is represented the main insect as a pathogen for phytoplasma disease occurring by insect-transmitted plant viruses in date palm orchards. Therefore, it is important to investigate the potential effect of some insecticides against such insect. The adults of leafhopper C. bipunctata were collected from date palm orchards in Alhasa, Eastern province, Saudi Arabia. Three insecticides from different classes--beta-cyfluthrin （pyrethroids）, imidacloprid （neonicotinoids） and abamectin （natural compounds）--have been evaluated in vivo against adults C. bipunctata. This stage was exposed to residual film of various concentrations of each insecticide on transparent plastic cups using a Potter precision laboratory spray tower. Bioassay test showed that both beta-cyfluthrin and imidacloprid caused 100% mortality by 500 ppm at 24 h after treatment, whereas abamectin gave the same mortality by 50 ppm at the same time. Toxicity values revealed that abameetin was the most potent insecticide compared with beta-cyfluthrin and imidacloprid, where the lethal concentrations LC50 and LC95 were 24.58 ppm and 116.73 ppm at 3 h after treatment, respectively. Therefore, abamectin can be a possible candidate to be applied on date palm or ground grass by the Ministry of Agriculture after successful field experiments.

Reduction in Fertility by Nerium indicum Leaves Extract in Adults of Red Flour Beetle, Tribofium castaneum （Coleoptera： Tenebrionidae） Compared with Coopex （Bioallethrin： Permethrin）

Recent trend for the control of insect pests has been towards the use of substances of plant origin. Reductionin fertility was determined in red flour beetle, Tribolium castaneum （Herbst.） by Nerium indicum Millleaves extract compared with coopex applied by contact method under laboratory condition. When adults were placed on filter paper treated With 7.86, 9.43, 11.01, 12.58 and 14.15 μL/cm2 doses of N. indicum leaves extract, fertility was 154 ± 15.2, 139 ± 15.0, 126 ± 6.0, 89 ± 12.2 and 72 ± 13.6 larvae/pair, compared with untreated and controls fertility （233 ± 16.0 and 190 ± 15.1 larvae/pair, respectively）. However, the reduction in fertility was 33.2 ± 6.4%, 39.7 ± 3.7%, 45.7 ± 2.9%, 58.0 ± 4.4% and 66.3 ± 5.1% by the same doses ofN. indicum extract. Moreover, adults treated with the same doses of coopex with the same method, fertility was 160 ± 14.6, 154 ± 9.3, 140 ± 11.2, 113 ± 7.5 and 71 ±- 4.8 larvae/pair, compared with controls fertility （211 ± 8.5 larvae/pair）, respectively. Furthermore, reduction in fertility was 24.3 ± 5.2%, 30.2 ± 6.4%, 37.2 ± 8.0%, 51.3 ± 1.4% and 58.8 ± 4.7% by the same doses of coopex. Minimum fertility was found in August and maximum was in July in both, N. indicum extract and coopex treated batches. The trend of reduction in fertility was the same in both N. indicum leaves extract and coopex, i.e., it was increased gradually from lower to higher doses. Nerium indicum leaves extract reduced fertility significantly compared with coopex.

Influence of Copper on Transport and Dissipation of Lambda-Cyhalothrin and Cypermethrin in Soils

Repeated applications of bordeaux mixture （a blend of copper sulfate and calcium hydroxide） and pyrethroid insecticides （Pys） have led to elevated copper （Cu） and Pys concentrations in vineyard surface soils. To understand the potential influence of Cu on the fate of Pys in the soil environment, we selected two Pys, cypermethrin （CPM） and lambda-cyhalothrin （A-CHT）, and two typical Chinese vineyard soils, Haplic Acrisol and Luvic Phaeozem, as experimental samples. The dissipation experiment was conducted at room temperature in the dark, and the transport of both Pys through the soils was investigated using soil thin-layer chromatography. The results showed that the transport of Pys in both soils increased as the Cu2＋ concentration increased from 0 to 100 mg L-1, and Pys were more transportable in Haplic Acrisol （HA） than in Luvic Phaeozem （LP） under the same experimental conditions. For CPM, only 100 mg L-1 of Cu2＋ significantly （P 〈 0.05） increased Pys transport through both soils relative to water. Lambda-CHT was significantly （P〈0.05） transported through HA by all the Cu2＋ concentrations compared to water, and all but the 1 mg L-1 of Cu2＋ significantly （P 〈 0.05） increased the transport of A-CHT through LP relative to water. However, the dissipation rates of CPM and λ-CHT decreased with the addition of Cu to soils. Our findings suggest that the risk of groundwater contamination by Pys increases in the soils with elevated Cu concentrations.