The Study Of The Multi-residue And Environmental Behaviors On Organotin Pesticides By HPLC-ICP-MS

In recent years, excessive use of organotin pesticides in agriculture and forestry have caused severe environmental pollution, and threaten human health through food chain. Organotin compounds of different structure have distinguishing biological toxicity. Developing the morphological analysis and studying the degradation behavior of organotin pesticides was of great practical significance to guide the scientific use of the pesticide and make the environmental and ecological safety evaluation. To now, studies of the organotin are focused on DBT and TBT but seldom about analysis method and environmental behavior. In present study, we used modern separation techniques to set up a new morphological analysis method of Triphenytin Hydroxide, azacyclotin and fenbutatin oxide in water and sediment samples. We investigated the hydrolysis, adsorption-desorption, water-sediment degradation of organotin pesticides by simulation test in lab, the results were as follows:1. A sensitive and accurate method for the simultaneous determination of three organotin pesticides in water and sediment samples by HPLC-ICP-MS has been developed. DELTA-PAK C18was selected as separate column, mobile phase of the HPLC was CH3OH:CH3COOH (7%)=90:10(v/v), the aqueous phase was adjusted to pH=3.5with triethylamine, and the flow rate was1.0mL/min. The three compounds behaved linearly from5to250μg/L with the coefficients over0.999. The average recoveries were between71.52%and114.93%and the RSD ranged from1.76%-16.30%.2. The adsorption of organotin pesticides in three kinds of sediments were studied with batch equilibrium technique. Adsorption isotherms of three organotin pesticides in sediments fit well with the isothermal adsorption equation, with correlation coefficent over0.9. The adsorption constant (Kd) of Triphenytin Hydroxide, azacyclotin and fenbutatin in West Lake sediment was851.6,1191.3and3540.3, respectively, while the Kd in pond sediment was1768.4,1850.8and5485.7, respectively. Those results indicated that all the three pesticides were easily adsorbed by those two sediments, moreover, the sediment adsorption capacities of organotin pesticides were positively related with the contents of organic matter. The adsorption free energy of these three organotin pesticides in two sediments were all less than40kJ/mol, suggesting that the organotin pesticides adsorption was atributed to physical process. 3. The kinetics of hydrolysis of organotin pesticides was studied in lab based on different pH buffer and temperature. The hydrolysis rate of three organotin pesticides fitted first-order kinetic equation. Hydrolysis half-life range of these three pesticides in different pH (4,7and9) at25℃and50℃were listed as:triphenytin Hydroxide (11.7to30.1d), azacyclotin (9.4d to25.6d), fenbutatin oxide (79.4to141.6d). Hydrolysis velocity in alkaline condition was greater than in acid and neutral condition. Temperature and organotin’s hydrolysis has notable positive correlation, the higher the temperature, the faster the hydrolysis.4. The degradation dynamic of organotin pesticides in the water-sediment system fit the first-order kinetics. In aerobic condition, the degradation half-life of Triphenytin Hydroxide, azacyclotin, fenbutatin oxide in the West Lake water-sediment system were36.5d、24.7d and53.7d, respectively, while in anaerobic condition, the half-life were63.1d、55.1d and73.7d, respectively. In aerobic condition, the degradation half-life of Triphenytin Hydroxide, azacyclotin, fenbutatin oxide in the pond water-sediment system were46.2d、44.4d and105.1d, respectively, while in anaerobic condition, corresponding data were53.3d、67.3d and123.8d, respectively. In one hand, the degradation rate of three organotin pesticides in the West Lake water-sediment system was higher than that in the Pond water-sediment system, in the other hand, the degradation rate in the water-sediment system in aerobic condition was greater than anaerobic condition. The proportion of microbial degradation in total degradation in the West Lake water-sediment system was greater than that in the Pond water-sediment system, and was smaller in aerobic condition than that in anaerobic condition of the two water-sediment systems. Total degradation was basically attributed to hydrolysis rather than microbe.5. Azacyclotin in xenopus laevis Did not show targeted accumulation trend. This study shows that the application of Azacyclotin for forgs is safe.A reliable and rapid method has been established to determine the residue of organotin pesticides in water and sediment samples. And the environmental behavior of organotin pesticides was investigated, including hydrolysis, water-sediment degradation and absorption. The degradation behavior results could be a helpful tool in controlling and monitoring the risks of organotin pesticide to human health and environment safety.