Dichlorvos degradation studied by 31P-NMR

We studied the hydrolysis and TiO₂ photocatalysis of the pesticide dichlorvos at pH 2.6–9 using phosphorus-31 nuclear magnetic resonance (³¹P NMR). We found that the hydrolysis of dichlorvos led to the formation of dimethyl phosphate at pH 5.6–9. On the other hand, TiO₂ photocatalysis decomposed dichlorvos into dimethyl phosphate, which further reacted to form monomethyl phosphate at pH 2.6 and 9. Monomethylphosphate was hydrolysed into phosphate at pH 2.6. ³¹P NMR is therefore a promising tool to study the degradation of organophosphorus pesticides.     

Organophosphate dichlorvos induced dose‐related differential alterations in lipid levels and lipid peroxidation in various regions of the fish brain and spinal cord

Abstract

The effect of dichlorvos (DDVP) (0–0, dimethyl 2: 2‐dichlorovinyl phosphate), on various lipid fractions and lipid peroxidation in the discrete areas of the brain and spinal cord were studied in the fresh water teleost (Heteropneustes fossilis). Fishes were exposed to three different doses (3.0, 6.0 and 9.0 ppm) of DDVP daily for 7 days. Dose‐related increase in the levels of total lipids, cholesterol and esterified fatty acids was detected in the fore brain, optic lobes, cerebellum, medulla oblongata and spinal cord. However, phospholipids were significantly decreased in the aforementioned regions of the central nervous system. The rate of lipid peroxidation was significantly increased in all the regions of the CNS.     

浊点萃取催化光度法测定蔬菜中的敌敌畏

基于有机磷农药对过氧化氢氧化联苯胺反应的催化作用,以敌敌畏为例,用Triton X-114为萃取剂,研究了该浊点萃取体系用于敌敌畏检测的特性。在pH值为8.5的氨缓冲溶液中,过氧化氢与盐酸联苯胺在敌敌畏的催化作用下生成稳定的黄色配合物,经浊点萃取测定其含量。配合物的最大吸收波长为425 nm,在0μg～250μg范围内吸光值呈良好的线性关系,相关系数为0.999 8,表观摩尔吸光系数ε为5.3×104L.mol-1.cm-1,方法检出限为22.2μg/L。用于5种蔬菜中敌敌畏的残留量分析,平均加标回收率为82.3%～102%,RSD≤8.9%。     

三氯甲烷中有机磷农药混合标准样品的研制

确立了三氯甲烷中有机磷农药混合标准样品的制备、分析和定值方法,进行了标准样品的均匀性检验、稳定性监测及协作定值数据的不确定度评价。结果表明,三氯甲烷中有机磷农药混合标准样品的均匀性良好,至少在18个月的时间内稳定。     

农药污染对土壤动物群落影响的实验研究

通过敌敌畏农药污染的模拟实验,研究了农药污染对土壤动物的影响。结果表明:随着敌敌畏农药处理浓度的提高,土壤动物种类数从低浓度(0.04mL/L)的53属(科)减少至高浓度(10mL/L)的26属(科);个体数则从低浓度占全捕量的14.1%减少到高浓度仅占全捕量的2%;而随处理时间的延长,对土壤动物的影响不太明显;大型土壤动物蚯蚓的染毒实验表明:蚯蚓可作为农药污染的重要指示动物。