Simultaneous Detection Of Sulfamethoxazole And Danofloxacin Residues In Milk By Fluorescence Spectroscopy

Antibiotics are often applied for the treatment of mastitis disease of the cattle and feedadditive for growth promotion. However, abuse of antibiotics or insufficient withdrawal timecan lead to accumulation of drug residues in animal tissues and products, which could causeallergic or resistant reactions, or even cancer in consumers. Effective monitoringmethodologies for antibiotic residues are essential to ensure food safety and protect consumerhealth. Fluorescence spectroscopy is characterized of rapid, sensitive and low cost. Detectingsingle class of antibiotics in bovine milk using the fast fluorimetric tools has been reported,but there are few studies on determination of multiple-classes of antibiotics using thecombined technique of fluorescence spectrum and chemometrics tools. For this aim, afluorescence assay was developed for simultaneous determination of sulfonamide andquinolone residues in bovine milk. It is nowadays commonly accepted that full spectrummultivariate calibration methods offer the advantage of speed in the determination of thecomponents of interest, avoiding separation steps in the analytical procedure and resolving theoverlapped spectra, in order to establish the simultaneous detection of multiple-classes ofantibiotic in food stuffs.In this study, the simultaneous detection of sulfamethoxazole and danofloxacin residuesin milk was investigated. Firstly, the fluorescence properties of the sulfamethoxazole anddanofloxacin were studied in aqueous solution. Rapid screening methods for detection ofsulfamethoxazole and danofloxacin residues in milk were established. The analytical methodswere validated according to the European Commission Decision2002/657/EC. Partial leastsquares discriminant analysis (PLSDA) was applied for the analysis of sulfamethoxazoleresidue in milk to screen samples containing residues with a level above the MRL, and theaccuracy was100%. A preliminary quantification could be acquired by further analysis withthe three-way partial least squares (PLS), and the recovery was82.7%~131.4%for all theunknown samples, and the decision limit (CCα) and detection capability (CCβ) was102.4μg/L and104.8μg/L, respectively. For detecting of danofloxacin, a robust method was alsoestablished which showed a significant discrimination between the control and spiked milksamples with non false negative by PLSDA model. The concentration of danofloxacin wasreceived by PLS algorithm, and recovery was86.4%~125.8%for all predicted samples, andthe decision limit (CCα) and detection capability (CCβ) was31.19μg/L and32.38μg/Lrespectively.Finally, a simultaneous detection of sulfamethoxazole and danofloxacin residues in milkby fluorescence spectroscopy was established based on the appropriate system parameters anddifferent chemometrics tools. The results showed that, nPLSDA model could distinguishbetween the negative and positive samples with a3.7%of false negative probability both forsulfamethoxazole and danofloxacin, and a quantification result could be acquired by nPLSmodel. For sulfamethoxazole, the recovery was4.5%~126.6%, and the decision limit (CCα)and detection capability (CCβ) was103.3μg/L and106.6μg/L respectively. For danofloxacin,the average recovery was70.2%~123.9%, and the decision limit (CCα) and detection capability (CCβ) was34.0μg/L and38.0μg/L respectively. The predicted concentrationcould also be required by PARAFAC model. For sulfamethoxazole, the recovery was72.4%~126.3%, and the decision limit (CCα) and detection capability (CCβ) was102.8μg/Land105.5μg/L respectively. For danofloxacin, the average recovery was81.5%~127.9%, andthe decision limit (CCα) and detection capability (CCβ) was32.5μg/L and35.0μg/Lrespectively. As a result, PARAFAC model is close to the nPLS model and both of the twoalgorithm shows the potential to screening multiple classes of antibiotic residues incommercial milk.The results showed that fluorescence technique combined with chemometrics methodscan achieve the fast detection of sulfamethoxazole and danofloxacin residues in milksimultaneously. This simple and sensitive method shows the potential to screening multipleclasses of antibiotic residues in commercial milk.