Study On Phoxim Dynamic Residue In Carassius Auratus And Its Impact On AChE

An analytic method,which involved matrix solid-phase dispersion（MSPD） followed by high performance liquid chromatography with diode array detector（HPLC）,was developed for the determination of phoxim residue in the muscle of carassius auratus. Dynamieal Rhythm of Phoxim in carassius auratus muscle was investigated by the method.The impaction of the insecticide in different time and different concentration on brain,muscle and liver of fish AChE was also studied.The mainly results were summarized as follows.In the study we primarily optimized the method of Matrix Solid Phase Dispersion-High Performance Liquid Chromatography（MSPD-HPLC） on phoxim residue in the muscle of carassius auratus.Under optimal conditions,0.5 g of tissue sample,are dispersed with 1.5 g of florisil and 0.5 g of anhydrous sodium sulphate and transferred to a cartridge.The cartridges were then eluted with 25ml of acetone-hexane（40:60,V/V）. The phoxim was separated on ODS column（4.6mm×250 mm i.d.,5μm） with methanol / water（50:50,V/V） as the mobile phase,and flow rate was 0.6 mL/min,then were detected by diode array detector at 270 nm wavelength with the injection volume 20μL. The linearity of the method was 0.01 mg/L-10 mg/L and the detection limit was 3.3μg/kg.At the added levels of 0.05 mg/kg,0.1 mg/kg,1 mg/kg,the recovery rates were in the range of 88%-112%with relative standard deviations between 1.1%and 6.3%.The method is timesaving,simple to operate and meets the requirement of the analysis of pesticide residues.The dynamieal rhythm of phoxim in different concentration in carassius auratus muscle was investigated by the method.The result showed that the pesticide began to appeare accumulative effect when the fish exposed to the phoxim in short time.And the residues then increased to a peak in 6 h-48 h.The residue of phoxim reached maximum at 6 h and then decreased when the fish exposed in 0.02 mg L^-1 concentration.And no sample was found containing residue after 120 h.The pesticide appeared accumulative effect in 48 h in fish muscle,then decreased slowly to low residue after 120 h when exposed in the middle(0.1 mg L^-1) and high(0.4 mg L^-1) concentrations.There was tiny residue in muscle after 144 h.The inhibition of brain and muscle reached peak at 72 h and 48 h in all treatment concentration,separately.The inhibition reached to maximum at 48 h when the fish exposed in the concentration of 0.1 mg/L and 0.02 mg/L.And when exposed in the concentration of 0.4 mg/L,the inhibition reached peak at 72 h.The activities was kept inhibiting when the fish exposed in middle and high concentration after the lab finished at 96 h.However,the activities recovered when the fish exposed in low concentration after 96h.The activities kept recovering after devolved to fresh water from phoxim environment.The activities come back to normal after 96 h.Finally,we studied on the relationship between the dynamieal rhythm of phoxim residu in muscle and the impact on ACHE.When the fish exposed in middle and high concentration of phoxim,the pesticide residue in muscle increased with the increasing of exposing time.Then it decreased when the residue reached peak.It was the same with the impact regularity on ACHE.When fish exposed in low phoxim,the maximum inhibition rate appeared lagged behind the maximum residue.Then the two decreased with the increasing of the.exposing time.This paper shows a method to determin phoxim residue in carassius auratus and affords reference for determination of the organophosphorous residue in other freshwater fish.The results suggest an active affect on guarantee the edible of aquatic products and provide reference to the investigation of aquatic safety.