乙嘧酚在黄瓜和土壤中的消解动态研究

利用高效液相色谱仪及田间试验方法,建立了乙嘧酚在黄瓜和土壤中的残留分析方法,研究了乙嘧酚在黄瓜和土壤中的残留消解动态,对影响残留分析方法的主要参数进行了优化。黄瓜和土壤样品分别用乙腈和丙酮提取,硅胶柱净化,高效液相色谱仪二极管阵列检测器检测,外标法定量。结果表明,该方法的最小检出量为3.5×10^-10 g,在黄瓜和土壤中的最低检测浓度分别为0.010和0.005 mg.kg^-1。乙嘧酚的平均添加回收率为80.5%～103.1%,变异系数为2.10%～3.74%。消解动态试验表明,乙嘧酚的残留量随时间延长而降低,消解动态曲线符合一级动力学方程,在黄瓜和土壤中的半衰期分别为3.5和9.9 d,属于易降解性农药化合物。乙嘧酚在黄瓜中消解速率高于其在土壤中的消解速率,这可能是由于黄瓜生长稀释作用导致的。     

噻菌茂在烟叶和土壤中的残留消解动态及安全性评价

为明确噻菌茂在烟草上使用后的环境安全性,建立了烟叶和土壤中噻菌茂残留的检测方法,并在山东和湖南两地开展了为期两年的噻菌茂在烟叶及其土壤中的消解动态和最终残留研究。结果表明,采用甲醇/水（70：30,V：V）提取,石油醚、二氯甲烷萃取,弗罗里硅土净化,高效液相色谱（HPLC-UV）测定,在0.01～5.0mg.kg-1添加水平下,噻菌茂在鲜烟叶、干烟叶和土壤中的平均回收率分别为90.50%～93.84%、88.19%～91.90%和88.34%～93.04%,相对标准偏差（RSD）分别为1.72%～2.79%、1.83%～4.13%、2.00%～2.71%。噻菌茂的最小检出量为1.4×10-12g,最低检出浓度分别为：鲜烟叶0.01mg.L-1,干烟叶0.01mg.L-1,土壤0.005mg.L-1。田间试验结果表明,噻菌茂在烟叶和土壤中消解较快,半衰期分别为2.85～3.44d和2.77～3.26d。噻菌茂可湿性粉剂按有效成分250g.hm-2（推荐高剂量）和375g.hm-（21.5倍推荐高剂量）于烟草旺长期-成熟期兑水施药3～4次,烟叶中噻菌茂最终残留量随采收间隔时间的延长而呈递减趋势,距末次施药后间隔7d采收的烟叶中噻菌茂的残留量为1.102～4.230mg.kg-1,21d残留量降为0.082～1.813mg.kg-1;而土壤中噻菌茂最终残留量均未检出（≤0.005mg.kg-1）。     

新型杀菌剂啶氧菌酯在田间黄瓜和土壤中的残留消解动态及残留分析

建立了黄瓜和土壤中啶氧菌酯残留量的检测分析方法,对啶氧菌酯在黄瓜和土壤中的消解动态及残留规律进行了研究。啶氧菌酯的最小检出量为3.5×10-11g;在黄瓜和土壤基质中的最低检出浓度均为0.005mg·kg-1。对黄瓜和土壤2种基质,设置了0.005、0.05、0.25 mg·kg-13个添加水平,每个添加水平设置5个重复,啶氧菌酯在黄瓜和土壤中的添加回收率为68.61%~122.4%,变异系数为1.06%~17.2%。田间试验结果表明:啶氧菌酯在天津地区黄瓜和土壤中的残留消解半衰期分别为5.71d和12.9 d,在山东地区黄瓜和土壤中的残留消解半衰期分别为2.70d和10.3 d,在江苏地区黄瓜和土壤中的残留消解半衰期分别为9.76d和14.9 d。距最后一次施药5d时,啶氧菌酯在黄瓜中的最高残留量为0.014mg·kg-1,远低于欧盟规定的黄瓜中啶氧菌酯最大残留限量0.05mg·kg-1。     

赛丹在棉花和土壤中的残留动态研究

用气相色谱法测定了赛丹在棉花叶片、棉籽和土壤中的消解动态及最终残留量，结果表明，在本地区特有的气候环境条件下，赛丹在棉叶和棉田土壤中消解速度较快，其半衰期分别为6．3d和15．0d。最终残留量的测定结果说明，赛丹在棉籽中无残留。     

辣椒中氟吗啉残留消解动态及膳食风险评估

为研究氟吗啉在辣椒中的残留消解情况及对居民的膳食摄入风险,本文采用高效液相色谱-串联质谱法测定氟吗啉在辣椒上的残留量,分析其消解动态规律。结果显示,氟吗啉在辣椒中的消解动态符合一级反应动力学方程,在浙江和湖南2个试验点的半衰期分别为3.4、 4.1 d。氟吗啉在辣椒中的长期膳食摄入风险商为0.013 8%;在所有登记作物中的总膳食摄入风险商为4.721 9%。膳食风险评估结果表明,氟吗啉在辣椒中的残留对人群膳食风险在可接受范围内,按照推荐使用剂量、喷药次数及安全间隔期在辣椒上施用50%锰锌-氟吗啉可湿性粉剂,辣椒中的氟吗啉残留不会影响我国居民身体健康。     

氟氯菊酯在棉花和土壤中的残留动态研究

用气相色谱法测定了氟氯菊酯（天王星）在棉花叶片、棉籽和土壤中的消解动态及最终残留量。结果表明，在本地区特有的气候环境条件下，氟氯菊酯在棉叶和棉田土壤中消解速率较快，其半衰期分别为8．7d和11．8d。最终残留量的测定结果说明，氟氯菊酯在棉籽中无残留。     

小麦和土壤中环丙唑醇残留消解动态及膳食摄入评估

为评价环丙唑醇在小麦生产上应用的安全性,通过建立乙腈提取、氮磷检测器检测方法对小麦籽粒、植株和土壤样品中环丙唑醇的残留量进行检测,研究了小麦籽粒、植株和土壤中环丙唑醇的残留及其消解动态,并对小麦中的残留量进行风险评估。结果表明,环丙唑醇在小麦籽粒、植株及土壤空白样品中的添加回收率为79.2%~95.6%,相对标准偏差为1.9%~10.0%,最小检出量为8.2×10?12 g,在小麦籽粒、植株及土壤中的最低检测浓度均为0.05 mg·kg?1,乙腈提取、氮磷检测器检测方法重现性好,准确度、精密度高,可满足环丙唑醇在小麦上的残留分析要求。2010年和2011年,河南省、黑龙江省和江苏省3地环丙唑醇在小麦植株和土壤中的消解半衰期分别为3.0~5.5 d、18.1~34.5 d;不同施药次数、施药量及采样间隔,环丙唑醇在小麦籽粒中的最终残留量均≤0.415 mg·kg?1。采收间隔期为14 d和21 d时,不同施药次数、施药剂量和采收间隔期,环丙唑醇在小麦植株、小麦籽粒和土壤中的残留量差异均不显著;采收间隔期为7 d,有效成分108 g?hm-2施药2次与有效成分162 g?hm-2施药3次时小麦植株、小麦籽粒和土壤中的残留量之间均存在显著性差异。普通人群环丙唑醇的国家估算每日摄入量为0.000 109 9 mg,占日允许摄入量的0.5%左右,按本试验方式进行施药,通常不会对一般人群健康产生不可接受的风险。     

猪肉中地塞米松兽药残留及摄入量风险评估

通过对华北某市猪肉中地塞米松兽药的残留监测,分析猪肉中地塞米松的残留水平,并评估其残留风险。试验采集500份猪肉样品,采用超高效液相色谱-串联质谱法对样品中地塞米松进行残留监测,并结合2015年我国居民膳食调查数据,使用专业风险评估软件@Risk,尝试构建非参数概率评估模型,对猪肉中地塞米松进行风险评估。结果显示,检测的猪肉中无超过国家限量标准(0.75g/kg)样品,含量范围为ND^0.38μg/kg(检出限为0.20μg/kg)。地塞米松兽药P99.5的暴露量EDI占ADI风险商HQ范围为0.0224~0.0635,远远<1,处于非常安全水平。结果表明,人群摄食动物性食品猪肉中的地塞米松兽药残留膳食性暴露风险较低,对人群不会产生不良作用。     

基于桔梅奇酵母冻干粉制备可湿性粉剂及其在柑橘上的应用

确保生防制剂的贮藏稳定性是保证微生物种群数量和生物防治效果不受影响的关键因素。为开发货架期较长且防治效果稳定的拮抗酵母生物制剂,该研究通过助剂的单因素筛选试验和混料试验研制出一种基于桔梅奇酵母冻干粉制备得到可湿性粉剂,经过升温加速贮藏试验预测制剂的贮藏稳定性,同时评价了制剂在离体和活体条件下对柑橘采后主要病害的控制效果。试验结果表明：试验筛选得到制剂优化配方的质量分数分别为皂角粉5.69%、亚甲基二萘磺酸钠8.74%、母粉85.57%。冻干制剂中酵母活菌数可达到4.72×108 CFU/g,贮藏稳定性试验表明,冻干制剂的贮藏稳定性较好,预测在4℃贮藏后制剂中酵母活菌数约为4.6×108 CFU/g。适当降低贮藏温度可延长冻干制剂贮藏期。离体试验发现,与新鲜酵母相比,液体制剂对柑橘采后病原菌的抑制作用无显著变化,抑菌圈可达到9 mm以上。在柑橘果实上能够有效控制柑橘果实采后青霉病、绿霉病、酸腐病和炭疽病,可将发病率降低约40%～70%。综上,对桔梅奇酵母进行制剂化能够延长其货架期并维持其对柑橘果实采后病害防治效果。     

Triflusulfuron-methyl dissipation in water and soil

This paper reports laboratory studies of the behavior and fate of triflusulfuron-methyl in aqueous buffer and soils. Aqueous hydrolysis was pH-dependent and fast in acidic buffer solutions. In basic buffers, the hydrolysis rate variation was low between pH 7 and pH 10. The degradation pathway in the range of pH 4-10 was via cleavage of the sulfonylurea bridge to form two transformation products: 2-amino-4-(dimethylamino)-6-(2,2,2-trifluoroethoxy)-1,3, 5-triazine (2) and 6-methyl-2-methylcarboxylate benzene sulfonamide (3). Comparison of transformation rates in sterile and nonsterile soils indicates that chemical and microbial processes are important in soil degradation. The former is more important in acidic soils, and the latter is more important in basic soils. A biphasic model fits well with dissipation of triflusulfuron-methyl in soil. The triazine formed during the first step of transformation was degraded more rapidly in basic soils than in acidic soils.     

Residue levels of ethoxyquin, imazalil, and iprodione in pears under cold-storage conditions.

A gas chromatographic method is presented for the simultaneous determination of the antiscald ethoxyquin and the fungicides imazalil and iprodione in peel and pulp of Blanquilla pears. Fruits were cold-stored in commercial chambers in normal atmosphere and in controlled atmosphere with low oxygen content (oxygen and carbon dioxide were held at 2.5% and 1.5%, respectively). The method uses gas-liquid chromatography (GLC) with an alkaline flame ionization detector (detector of N-P, NPD) and allows the detection of the mentioned compounds to minimum levels of 0.08-0.12 mg/kg in fresh fruit. With this system the evolution of residues in fruit was monitored throughout the period of cold storage. In the surveys carried out the residue levels of these compounds were found to be below the limits allowed by the legislation of European Union. For the three studied products residues in pulp are lower and disappear more quickly than in peel.     

Dissipation rates of cyprodinil and fludioxonil in lettuce and table grape in the field and under cold storage conditions

Two fungicides (cyprodinil and fludioxonil) have recently been used in southeast Spain to control disease in lettuce and grape. Gas chromatography with a nitrogen-phosphorus detector (GC-NPD) was used to study the disappearance of these compounds from crops under field conditions and during refrigeration. Residual values 21 days after application were below the maximum residue limit (MRL = 0.05 mg kg(-1)) established by Spanish law in the field experiment for both compounds. However, with the exception of fludioxonil in lettuce, residues were above the MRL in the refrigerated farm produce for both fungicides. The half-lives were 3-6 times greater under refrigeration.     

戊唑醇在猕猴桃中的残留行为及膳食摄入风险评估

采用超高效液相色谱-串联质谱方法研究了戊唑醇在猕猴桃中的消解动态及最终残留水平,并对我国不同人群的长期膳食摄入风险进行了评估。在0.01、 0.10、 1.00和2.00 mg/kg添加水平下,戊唑醇在猕猴桃中的平均回收率为89%～114%,相对标准偏差范围为0.6%～8.2%,定量限为0.01 mg/kg。消解动态结果表明,戊唑醇在猕猴桃上的消解速率符合一级反应动力学方程,半衰期为2.6～6.3 d。在安全间隔期14 d时,猕猴桃中戊唑醇残留中值为0.510 mg/kg,结合我国戊唑醇登记情况和居民膳食结构,计算得到一般人群戊唑醇的估算日摄入量是0.387 48 mg,占ADI的20.5%。不同年龄段人群中长期膳食摄入风险随年龄的升高呈下降趋势。25%戊唑醇可湿性粉剂按有效成分62.5～100 mg/kg剂量,施药2次,安全间隔期为14 d时,戊唑醇在猕猴桃中的残留不会对我国不同年龄段人群健康产生不可接受的风险。     

Liquid chromatographic determination of bendiocarb in technical materials and wettable powder formulations: collaborative study

A liquid chromatographic method for determination of bendiocarb in technical materials and wettable powders was tested by 12 collaborators. Bendiocarb is dissolved in acetonitrile containing 0.1% propiophenone as internal standard. This solution is analyzed on a liquid chromatograph utilizing a reverse phase (C18) column. The compound is detected at 254 nm and peak area is used for quantitation. The 3 different materials studied contained 20, 80, and nominally 100% bendiocarb. Each was examined in duplicate to provide the necessary matched pairs. Collaborators approved of the ease and simplicity of the method and, in particular, the way the method can be applied to automatic injection assemblies. The statistical data show acceptable precision of the method: Reproducibility coefficients of variation were 20% material, 2.04%; 80% material, 1.02%; and nominal 100% material (technical product), 0.64%. The method has been adopted official first action.     

Strategies for risk assessment of existing chemicals in soil

In the risk assessment of industrial chemicals, an assessment of the risk to soil should be performed whenever relevant inputs occur via the following pathways: application of sewage sludge, wet or dry deposition, application as a pesticide constituent (e.g. solvent or metabolite), irrigation. An evaluation of the results for 34 chemicals from the first EU priority list showed that only 35% of the risk assessments for the terrestrial compartment were performed on the basis of at least 2 valid tests with soil organisms. In the vast majority of cases, the equilibrium partitioning method was used to extrapolate from aquatic to soil toxicity. However, no indications exist for a correlation between aquatic and terrestrial toxicity. Moreover, the exposure routes for soil organisms (uptake via pore water, air included in soil pores, ingestion of soil particles) are much more complex than those for aquatic organisms. As a new approach, it is therefore suggested that, in cases of relevant exposure (e.g. estimated or measured concentrations of >10 μg/kg), an assessment should generally be performed on the basis of valid terrestrial tests rather than on an extrapolation from the aquatic toxicity. It is recommended that prolonged exposure tests should be used already for an initial assessment of substances that have a strong tendency to adsorb on soil particles and thus a long residence time in soil. A decision scheme for the risk assessment of industrial chemicals in soil is presented, trigger values, testing strategies as well as assessment factors for derivation of a Predicted No Effect Concentration (PNEC_soil) are discussed. An example of a terrestrial risk assessment for substances from the first EU priority list is given in order to illustrate current practice.