The Studies On Determination Of Pyrethroid Pesticides Residues And Their Residual Eliminations In Grass Carp

Synthetic Pyrethroid Insecticides(SPI) is a new kind of pesticide which had growed up since 1980s,due to the characteristic of high performance,broad-spectrum.safety and low-poison to people and livestock,SPI has been applied in acquaculture widespreadly,but the residus of SPI in fishery product will cause larvaceous threaten to the mankind health and ecological environment.In order to monitor SPI residues in fish,choosed the representative drug of cypermethrin and fenvalerate,a multi-residue determination for cypermethrin and fenvalerate in Grass carp muscle adhering skin was developed,throughing of the gas chromatography with electron capture detector(GC-ECD).To determine residues of cypermethrin and fenvalerate in Grass carp from some parts of Chongqing,moreover,the residual elimination of cypermethrin and fenvalerate in Grass carp also studied.The study had the following three parts.In the first part,the gas chromatography with electron capture detector(GC-ECD) was established for the muli-residue determination of in Grass carp muscle adhering skin.Dioctylphthalate was used as interal standard substance,the drugs from muscle sample of Grass carp were extracted by petroleum,the extraction was purified throughing florisil chromatogragphin column with the elutriant of petroleum and acetoacetate,the elutriant was concentrated with vaccum rotary evaporation at 45℃,the metered volume reach to 1mL,and detected by gas chromatography.The chromatographic condition:⁶³Ni-ECD as detector,DM-1 with elastic quartz capillary chromatographic column,the detector temperature was 320℃,the inject temperature was 280℃,the column temperature was temperature programming:the initiate temperature was 200℃,remained 0.75min,then rised to 285℃with the rate of 20℃per minute, remained 10 minute,The precolum pressure was 0.08MPa.The nitrogen gas flew was 38mL/min.No split stream samping.The sample volume:1μL.The result showed that the calibration graphs for the two drugs were liner range from 1μg/kg to 100μg/kg,and their regression coefficients were above 0.999.The extraction recovery rates of cypermethrin and fenvalerate ranged from 92.65%to 100.13%and 93.37%to 99.14%,the method recovery rates ranged from 93.74%to 100.51 and 97.68%to 102.07%respectively.The intra-day coefficient variations(CV) were less than 4%,the inter-day coefficient variations were less than 8%.The limit of detection for the two drug were 0.3μg/kgå’Œ0.6μg/kg.The results suggested that the method has easy operation,high sensitivity,reproduction,recovery and selectivity,and provided theoretical foundation for the studies on the multi-residue determination and residual elimination law of cypermethrin and fenvalerate in Grass carp.In the second part,the residues of cypermethrin and fenvalerate in Grass carp from some markets of fishery product in Chongqing were detected by the multi-residue determination method.The result demonstrated that the positive detection rate of the two drugs were less than 7%, and the residue level were less than 3μg/kg,which below the MRLs stipulated by the nation.It indicated that the use of the two drugs in the aquiculture of Grass carp was comaparatively standardized in the detected regions.In the third part,the residual elimination law of cypermethrin and fenvalerate in Grass carp muscle was studied by the multi-residue determination method.Actual aquacultural conditions were simulated in this study.At the water temperature of 18±2℃,healty Grass carp had been separated two experiment groups and one group,there were 100 fish(mean body weight of 120 g) in per test group and 20 fish in the control group,the experiment began after 10d-dmestiction.In the first test group,sprinkled 4.5%cypermethrin emulsifiable in water once made its concentration 0.86μg/L.In the second test group,springkled 20%fenvalerate emulsifiable in water once made its concentration 3.64μg/L.The control group were not added drug.Fish were sampled on 0.5d,1d,2d,4d,6d, 8d,14d,16d,19d,23d,28d,34d,39d,43d,48d and 52d after drug withdrawal,respectively.Eevery time five samples were collected randomly.The squama of fish were wiped off and the muscle including skin were fetched.After preparation,the residues of cypermethrin and fenvalerate were determination by GC-ECD,the results were as follow.The drug concentration-time data of cypermethrin and fenvalerate were best described by two-compartment model.The main pharmacokinetic parameters of cypermethrin and fenvalerate in Grass carp muscle were respectively as follows:Tmax(peak time) were 4.00d and 6.00d,Cmax(peak concentration) were 21.34μg/kgå’Œ67.33μg/kg,T_1/2(half-time of absorption) were 2.88d and 6.25d,T_2/2(half-time of elimination) were8.72d and 7.15d,AUC(area under concentration-time curv) were 261.92 d.μg/kg and 1218.65 d.μg/kg,CL_B(total body clearance) were 0.004μg/kg.d and 0.016μg/kg.d.The results showed that the two drugs of cypermethrin and fenvalerate in Grass carp muscle had rapid absorption,long stagnation and slow elimination.Through the program of WT1.4,At this experiment conditions, the predicted withdrawal time of cypermethrin and fenvalerate were 12.31d and 24.85d for Grass carp.For the practical cultivation,considering the temperature of water,the quality of water,the density of fish and the uniformity of the absorbentia,the predicted withdrawal time of cypermethrin and fenvalerate for Grass carp extended to 20d and 35d.