| Objective Penicillin G?PENG?drug and bisphenol A?BPA?contaminants residues with trace-level in milk were detected by using surface-enhanced Raman scattering?SERS?technique.The proposed method not only can overcome the defect of existing technology and further extend the applicability of SERS technique in the field of the actual analysis,but also can provide new ideas and methods for the rapid and the high sensitive analysis of PENG drug and BPA contaminants residues in milk.Methods Noble-metal nanoparticles?Ag NPs and Au NPs?colloids were prepared by using the method of the chemical reduction.Ag NPs assembly substrate with SERS enhanced activity was prepared on glass slide by self-assembly technique.Under the assistance of aggregation agents?sulfates?,Au NPs modification substrate with SERS enhanced activity was prepared by halide modifying Au NPs.The two-step pretreatment method was adopted for treating the spiked milk sample?PENG and BPA?and the supernatant of the spiked milk sample was obtained.Ag NPs assembly substrate and Au NPs modification substrate were assembled with the supernatant of the spiked milk sample?PENG and BPA?,respectively;Ag assembly substrate with PENG drug molecule and Au modification substrate with BPA molecule were obtained.The characterized SERS peak of target analyte?PENG and BPA?in milk sample and their characterized normal Raman peak were contrastively analyzed.The SERS signals of PENG drug molecule?on the Ag substrate?and BPA molecule?on the Au substrate?were analyzed under different conditions?the qualitative identification and the quantitative analysis?.Results The qualitative and quantitative analysis of PENG drug and BPA contaminants residues in milk was realized by SERS technique.With the lower concentration range of 1×10-3?1×10-8 mol/L,there is a good linear relationship?R2=0.9902?and the limit of detection?LOD?is 2.54×10-9 mol/L?equal to 0.85?g/kg?,which is far lower than the standard of European Union?4?g/kg?.By this method,the recovery of PENG ranges from 76%to 97%with relative standard deviations?RSD?between 4.8%and 2.1%.Under the assistance of aggregation agent?ZnSO4?,the Raman signal of BPA residue on Au NPs modification substrate was enhanced greatly.There is a good linear relationship?R2=0.990?in the lower concentration range of 1×10-3?1×10-8 mol/L,and the LOD can be reduced to 4.3×10-9 mol/L(equal to 0.98×10-3 mg/kg),which is far lower than the standard of European Union?0.6 mg/kg?.By this method,the recovery of BPA residue ranges between89.5%and 100.2%with RSD between 4.6%and 2.7%.Conclusions In this study,surface-enhanced Raman scattering spectroscopy technique using noble-metal NPs as SERS-active substrate was first applied for detecting study of penicillin G drug and bisphenol A residues in milk.The results prove that the proposed SERS method can realize the rapid and high sensitive determination of PENG drug and BPA residues.The proposed method not only extends the actual application ranges of SERS technique,but also establishes the foundation for detecting study of the two contaminants?PENG and BPA?residues in milk. |
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