| Antibiotics have been used in large quantities with the development of poultry farming,and have played an important role and achieved positive results since their development.However,some farming enterprises,in pursuit of profit maximization,abuse antibiotics illegally,and antibiotic residues in poultry accumulate in human body and cause harm through the food chain.At the same time in the form of parent or metabolites excreted into the environment,posing a threat to the environment and human health.Therefore,it is particularly important to monitor antibiotic residues in poultry tissues as well as in waste.In a few studies in the drug literature in hair,it was shown that antibiotics are present in feathers in an undecomposed state and are a suitable substrate for detecting antibiotic use in poultry production.Even though there are no visible traces in edible tissues,analysis of feathers can determine to document any illegal antibiotic additive treatments and to monitor the phenomenon of antibiotic resistance.There is a near gap in the status,contamination level and distribution characteristics of antibiotic residues in poultry,especially in litter(feathers and manure),and a lack of studies on antibiotic elimination patterns during poultry farming.Therefore,this study focused on this area and combined high performance sample pretreatment techniques with liquid chromatography-novel mass spectrometry coupled with four classes of antibiotics,including quinolones,sulfonamides and sulfonamide synergists,quinoxalines and tetracyclines,to establish a high throughput,rapid and sensitive simultaneous detection method for four classes of antibiotics in chicken feathers and other matrices.And on this basis,the residues of antibiotics in chicken tissues and the metabolic elimination pattern were analyzed.Further study the elimination and transformation laws of antibiotics in chicken feathers and other wastes from dosing to resting process.The details are as follows:(1)An Ultra performance liquid chromatography tandem mass spectrometry,UPLC-MS/MS method was developed for the simultaneous determination of 26 Quinolones,QNs in chicken feathers.The experiment was simple and stable,and the linearity of the 26 QNs was good in a certain concentration range with the correlation coefficient greater than 0.99.The recoveries and coefficients of variation were78.9%～110% and <14.6% at the standard spiked levels of 10,100 and 200 μg/kg,respectively.The limits of detection(LOD)and limits of quantification(LOQ)were 0.12～1.31 and 0.96～2.60 μg/kg,respectively,which could meet the simultaneous separation and determination of 26 QNs.Enrofloxacin(ENR)was selected for chicken feeding experiments,and the residue metabolism and transmission characteristics of drug daily intake from mother to chicken feathers were studied in depth.The results showed that ENR residues in chicken feathers accumulated gradually after drug administration,peaked on the 5th day of drug withdrawal and remained relatively stable for at least 5 days,and it took about 49 days to metabolize ENR residues in chicken feathers to the level of complete elimination after the rest period.(2)An ultra performance liquid chromatography tandem quadrupole/high electrostatic field orbital ion trap high resolution mass spectrometry(UPLC-Q Exactive HF,HRMS)method was developed for the simultaneous determination of 26 sulphonamides(SAs)and 5 sulphonamide synergists(SAS)in chicken feathers and different tissues.The recoveries of the 31 compounds were in the range of 81.0%to 112.1% at different concentration levels.The LOD and LOQ ranged from 0.1 to 1 μg/ kg and 0.3 to 3μg/ kg,respectively,which were satisfactory for the simultaneous determination of the 31 compounds in each tissue.Sulfaquinoxaline(SQX)and its synergist Diaveridine(DVD)were used in a feeding experiment to study the metabolism and elimination of residues in tissue samples and waste.The residues of SQX in muscle were still present at 21 days of rest.Residues in feathers were relatively low,but metabolism was slowest.The resting periods of SQX and DVD in different tissues were calculated using WT1.4 software.(3)A method was developed for the simultaneous determination of 5 quinoxalines(QELs)and 3metabolites in chicken feathers and different tissues by UPLC-Q Exactive HF,HRMS.8 compounds were linear over a range of concentrations with correlation coefficients greater than 0.999.the recoveries of all tissues spiked at different concentration levels reached The recoveries of the tissues at different concentration levels ranged from 72.8% to 112.8%.The LOD and LOQ were in the range of0.04-0.1 μg/kg and 0.12-0.3 μg/kg,respectively,for the simultaneous determination of the eight compounds in each tissue.Olaquindox(OLA)and quincetone(QCT)were selected for feeding experiments to study the residual metabolism levels and elimination patterns in each tissue sample and waste,and to investigate the permeation levels of the chicken feeding experiment to the soil in the environment,the results showed that: the OLA residual marker 3-methyl-quinoxaline-2-carboxylic acid(Methyl-The results showed that the residual marker of OLA,methyl-quinoxaline-2-carboxylic acid(MQCA),reached its peak on day 1 in liver,kidney,sebum,muscle and blood;QCT reached its peak on day 3 in muscle;MQCA was still detected in sebum,muscle and blood at 21 days of rest.The resting periods of MQCA and QCT in different tissues were calculated using WT1.4 software.The highest residue level of MQCA was 67.28μg/kg,which penetrated to about 7.5～10cm in the 5th layer of soil;the highest residue level of QCT was 8.34μg/kg,which penetrated to about 4.5～6cm in the 3rd layer of soil.(4)An ultra performance liquid chromatography tandem quadrupole/linear ion trap mass spectrometry(UPLC-QTRAP)method was developed for the simultaneous determination of eight tetracyclines(TCs)in chicken feathers.The linearity of the eight TCs in feathers was good in a certain concentration range with correlation coefficients >0.999.The recoveries of each tissue were82.79%～101.95% at different concentration levels of addition.The LOD and LOQ were 0.3 μg/kg and 1μg/kg respectively,which could meet the requirements for the effective simultaneous determination of these 8 TCs in chicken feathers.The foundation for the next step in the study of residual metabolism patterns was laid. |
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