Fate Of Avermectin In Aquaculture Environment

In this paper, the accumulation and elimination of avermectin (AVM) in Carassiusauratus gibelio and Eriocheir sinensis, the migration, distribution, enrichment,degradation and elimination in aquaculture environment has been studied by establisheddetection methods for AVM in water, sediment, Elodea nuttallii, tissue of Carassiusauratus gibelio and Eriocheir sinensis using ultra high performance liquidchromatography tandem mass spectrometry (UPLC-MS/MS).In this study, UPLC-MS/MS is the detection means. Water samples diluted by equalvolume of methanol and detected directly after membrane filtration. Sediment, Elodeanuttallii, tissues of Carassius auratus gibelio and Eriocheir sinensis were extracted byacetonitrile combined with QuEChERS and cryopreservation method for samplepurification. The linear range in sediment and Elodea nuttallii were0.05~2μg/kg,0.5~20μg/kg, respectively. The linear range in water and plasma were0.1~50μg/L,0.4~75μg/L, respectively, muscle and liver were0.5~50μg/kg, gill and kidney were0.5~100μg/kg. It has a good linear range for regression coefficient (r2) greater than0.98. Thelimit of (LOD) for AVM in water and sediment were0.03,0.02μg/L, respectively, andthe limit of quantification (LOQ) were0.10μg/L and0.05μg/L, respectively. LOD inelodea nuttallii and animal tissues is between the range of0.15~0.20μg/kg, while theLOQ range is0.40~0.50μg/kg. The average recovery is between85%and115%, andboth the intra-day and inter-day coefficients of variation were less than8%. In thismethod, the LOQ and LOD were lower than the maximum residue limit (MRL) ofAVM in plant and animal foods with advantages of fast, simple, high sensitivity,reproducibility, specificity, less solvent consumption, etc. It is suitable for rapiddetection with a large number of samples to meet pharmacokinetic analysis andconventional residue detection tasks.In order to investigate the differences from different adminstration. Theaccumulation and elimination of avermectin in water and Carassius auratus gibeliohave been studied following bath exposure at three consecutive doses of2μg/L everyother day and at a single dose of6μg/L. The results showed that the avermectin inwater were eliminated by first-order exponential rate and half-life times (t1/2) were63hfor both three consecutive exposure and single exposure. The avermectin concentrationsin water were below0.5μg/L in240h. The avermectin concentrations in plasma and muscle increased at first following bath exposure and then decreased after peak time.The avermectin concentrations in plasma were significantly higher than that in muscle.The peak concentration (Cmax) of plasma following three consecutive dosage and asingle dosage were34.97μg/L and66.62μg/L, respectively; while the area under theconcentration-time curve (AUC0-t) were9871.2(μg/L·h) and18119.6(μg/L·h),respectively. The Cmaxin muscle were4.42μg/kg and15.80μg/kg, respectively, andAUC0-twere641.9(μg/kg·h) and4271.0(μg/kg·h), respectively. Accumulation ofavermectin in blood and muscle after a single exposure was more significant than thatfollowing three consecutive exposure. Regarding of10μg/kg as avermectin maximumresidue limit (MRL) in muscle, the withdrawal period of avermectin in muscle was295.4h and454.5h for three consecutive exposure of2μg/L and single exposure of6μg/L by the95%confidence interval analysis.In order to further explore the accumulation and elimination of avermectin indifferent aquatic animals or tissues, the migration, distribution, and elimination ofavermectin in aquaculture environment, this research also studied the fate of avermectinin simulated aquaculture environment. The result showed that AVM concentration intissues of carassius auratus gibelio maintained a high value while AVM could bedetected only in gill of Eriocheir sinensis. Th results also showed that AVM could shiftto sediment and Elodea nuttallii from water continuely. The accumulated of AVM inElodea nuttallii is stronger than sediment. The half-life of AVM in water, sediment andElodea nuttallii are63,115.5and346.5h.In conclusion, drugs could directly impact on both parasite and non-target creaturessuch as aquatic animals. AVM could be absorpted and enriched by aquatic animals andimpact food safety. The way for absorption and processing is different in carassiusauratus gibelio and Eriocheir sinensis which indicated that AVM could make differentinfluences on aquatic animals. In addition, the migration, distribution, accumulation andelimination of abamectin in aquaculture environment provided basic data for the safeuse of evaluation in aquaculture.