Optimization And Application Of Detection Method Of Sulfonamides Residues In Eggs And Veterinary Pharmaceuticals

The new version of the national food safety standard maximum residue limit of veterinary drugs in food(GB 31650-2019)further reduces the residue limit of sulfonamides in eggs from 100 ng/g to 0.5 ng/g.It not only puts forward higher requirements for the detection methods of sulfonamides residues,but also puts forward higher requirements for the production quality control of veterinary drug enterprises and breeding enterprises.In this paper,the Liquid Chromatography combined Mass Spectrometry(LC-MS/MS)detection method of sulfonamides residues in eggs was optimized,the residue detection limit(LOD)was further reduced,and the rapid detection of large quantities of samples was realized,which can be used as the internal control method of breeding enterprises.At the same time,the detection process of sulfonamides residues,which is preliminarily screened by Colloidal gold test strip method and rechecked by our optimized LC-MS/MS method,is established for the detection of sulfonamides residues in veterinary drug preparations and waterline,which provides a reference method for the internal control of veterinary drug production enterprises and breeding enterprises.1.Optimization and application of detection method of sulfonamides residues in eggsIn this study,LC-MS/MS method was used to detect the residues of sulfonamides in eggs,and the sample pretreatment methods were optimized,including extraction,purification and concentration methods.After the egg sample is extracted with 90%acetonitrile/water solution,it is purified with Prime-HLB and detected with LC-MS/MS instrument.The LOD of this method in the whole egg sample can reach 0.25 ng/g and the quantitative limit(LOQ)is 1 ng/g.The linearity are greater than 0.99 at the concentration of 1～5 ng/g.The recovery is between 80%～120% at 1,2 and 5 ng/g.The coefficient of variation(CV)within and between batches is less than 0.23,Meet the requirements of methodology.The method does not need nitrogen blowing and re dissolution,is suitable for mass sample processing,has low LOD under the conditions of existing instruments,is convenient and fast,and is suitable for internal control detection of products in breeding enterprises.Along a bus line from the suburb of Wuhan to the urban area,we randomly collected 86 native eggs from various supermarkets,farmers’ markets and farmers’ self-supporting.All samples did not exceed the standard,but the sulfachlorpyridazine in farmers’ free range native eggs was close to the market access limit.2.Detection method of sulfonamides residues in veterinary preparations and waterlineCombined with literature reports and production practice,this study analyzed the possible causes of sulfonamides drug residues in eggs of laying hens breeding enterprises.The combined production of different veterinary drug preparations in pharmaceutical enterprises and drug residues in water lines and feeding lines of breeding enterprises may be the important reasons.In this study,the detection process of primary screening with Colloidal gold test strip method and retesting with our optimized LC-MS/MS method was established to detect the residues of sulfonamides in veterinary pharmaceuticals and simulated waterline.Firstly,we added different kinds and doses of sulfonamides to tap water and Tiamulin Fumarate Soluble Powder respectively,and verified the commercial colloidal gold detection method of sulfonamides.It was found that the specificity of colloidal gold test paper was good,but the detection limits of colloidal gold for different sulfonamides were different and could not be accurately quantified.Since a certain amount of veterinary drug residues are allowed in the products of veterinary drug production,we put forward the enterprise internal control limit of 0.1ng/mg sulfonamides according to the existing literature,and developed a quantitative detection method for this limit.Add 10 ml extraction solvent to the veterinary drug preparation,fully vortex dissolve,centrifuge at 4000 r/min for 10 min,and then take the supernatant for detection with LC-MS/MS instrument.For 10 sulfonamides,the LOD is0.1 ng/mg and the LOQ is 1 ng/mg.The linearity are greater than 0.99 at the concentration of 1～5 ng/mg.The recovery is between 80%～120% at 1,2 and 5 ng/mg.The detection method can effectively monitor the degree of veterinary drug pollution,and is suitable for the internal control of veterinary drug enterprises and the quality control of veterinary drug procurement of breeding enterprises.