Studies On Determination And Degradation Of Tetraclines In Honey

In bee industry,oxytetracycline (OTC), tetracycline (TC),chlortetracycline (CTC) and doxycy-cline (DC) are the four tetracyclines (TCs) commonly added to the suger water as feedstuff b-y beekeepers for the treatment of infectious American and European foulbrood diseases and, the refore, trace residues can be found in honey. During the manufacture, machining, storing, trans-porting and selling of honey product, significant epimerization of residual TCs occur with prop-er temperature, moisture in a given time,the metabolites of which, so called epimers (ETCs), are also poisonous. To limit the damage from these drug exposure, the development of multi-residue determination is more adequate for surveillance purposes.As many determination of TCs are existing all the way, however, few studies have addr-essed the Epimers. A method for simultaneous determination of4tetracyclines and3epimersin honey samples was developed by liquid chromatography coupled with tandem mass spe-ctrometry in this essay. The TCs/ETCs resdues in honey samples were extracted using EDTA-Mcllvaine buffer extraction solution(pH5.0),then cleaned-up and pre-concentrated by hydrophilic-liphophilic balance (HLB)cartridge and weak cation exchange (WCX,Carboxylic Acid) sequentia-lly. Qualitative and quantitative analysis were carried out by ESI-MS/MS in MRM mode after the chromatography separation on Cis colum, with methanol-0.1%formic acid solution as mobi-le phase with gradient elution.The recoveries of the samples spiked at trace levels were in the range of64.9%-91.0%with the relative standard deviation(RSD) less than9.7%. The detection limits were1μg/kg for OTC、TC、4-epitetracycline(ETC)、4-epioxytetracycline(EOTC) and2μg/kg for CTC、DC、4-epi chlortetracycline(ECTC). The method is sensitive and reliable, and can be successfully applied to the simultaneous detection of7target tetracyclines residues in honey, three of which are toxic metabolites.Then we come to investigate metabolism regulars of TCs in honey just by the new method previously established.The posiible environmental factor were studied before certain processing, storage conditions were simulated.The simulated samples of diferent residual levels were batc-h quantity analysised,statistical analysised and conducted into mathematical models.The results showed that:(1) Instability of TCs and ETCs is clear, and they can be photodegraded very quickly under ultraviolet radiation and sunlight,but for honeys preserved in dark place,the degradation of TCs mainly depend on hydrolysis reaction. The product of hydrolysis are epimers, and the main affecting factor are ambient temperature(while manufacturing and storing)、time(while manufacturing and storing)、 concentration of initial residue.(2) By the factorial designs,complete quadratic regression model of TCs and ETCs during machining are established.(3) By quadratic orthogonal experiment, complete quadratic regression model of TCs and ETCs during machining are compulated.Oboved models clearly expounds how the temperature、time、concentration of initial residue affect residue and degradation of TCs and ETCs.That can be used to the actual when production management and clinical medication,to some extent.