| Anesthetic tricaine mesilate and also known as MS-222, is widely used in theworld, since it is convenient, safe and its obvious effect, it has been approved by theFood and Drug Administration in fish and other cold-blooded animals. Despite theapparent safety of this drug, it is not registered in many countries for veterinary use.In this situation, residues of tricaine are not allowed to occur at any concentration. Inorder to ensure food safety, the drug residues in aquatic must be controlled strictly.Detecting residual concentration of MS-222can improve the security of aquatic,therefore, it is necessary to establish the detection method of MS-222in aquaticanimals, and research the accumulation and elimination rules of MS-222in thetissues of aquatic.In this paper, a method for detecting the residues of MS-222in aquatic by liquidchromatography-tandem mass spectrometry (LC-MS/MS) has been developed.Residues were extracted from homogenized tissues with methanol at a volume ratioof50:50and acetic acid-sodium acetate buffer (pH4.2), the extract passed through aC18solid-phase extraction column followed by LC-MS/MS analysis, externalstandard method fix quantity. The chromatographic column was MGⅡ C18, mobilephase was0.5%formic acid and acetonitrile (v:v=60:40), flow rate was0.2mL/min.The mass spectrometry was performed in positive mode, using parent ion atm/z166, m/z138was used for quantification and m/z77was qualitative ion. Thelimits of detection were1μg/kg. The recoveries in aquatic were in the range of80%-110%. This method is simple and reproducible, and it has a high recovery.Secondly, choose turbot for the determination of effective concentration ofMS-222at water temperature12-13℃.The effects of MS-222, on behaviors of turbotwere examined, including changes of characteristic behavior during anesthesia andrecovery process, changes of respiratory rate during anesthesia process as wall as the survival rate after medicated bath for60h, eventually, it can be concluded that theeffective concentration of MS-222for turbot is60mg/L.Finally, the accumulation and elimination rules of MS-222in turbot have beenstudied. The body length and body weight of the turbot were20-25cm and250-350grespectively. The concentration of MS-222was60mg/L and duration of anesthesiawas60h. Then the turbot were transferred into fresh seawater for eliminationprocess, randomly selected three turbot for concentration determination every4hours. The results show that the maximum concentration in muscle can reach to4.78±1.88mg/g, while the enrichment capacity of MS-222is comparatively strongerin the liver, which can reach to6.79±1.51mg/g. The elimination time betweenmuscle and liver is also different, which is48h and52h respectively. Because manyfactors affect residues of aquatic animals, the accumulation and elimination rules indifferent turbot are not the same exactly. In this condition, when the temperature is12℃~13℃, bath time for60h, off-period is3days is advised.The results indicate that as an anesthetic to turbot， MS-222is feasible in terms ofthe effects that fish can be induced anesthesia rapidly and recovery rapidly, fishwhich are anesthetized by MS-222are safe after transferred into fresh seawater forelimination process. |
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