High sensitive detection of penicillin G residues in milk by surface-enhanced Raman scattering.

The antibiotic residue in animal source foods (milk, meat, etc.) is threatening people's health due to its abusing in livestock breeding more and more seriously. In this study, a simple and sensitive SERS method coupled with a two-step pretreatment process of sample was proposed for the residue detection of penicillin G (PENG) in real milk sample. It can be found that the two-step pretreatment process of sample is an essential procedure for the successful detection of PENG residue in milk, which can effectively avoid interference from other components in the sample and achieve the trace-level detection of PENG residue by SERS. Under the optimal test conditions, the limit of detection of PENG residue is 2.54×10-9mol/L (equal to 0.85μg/kg), which is lower than the standard of the European Union (4μg/kg). And, there is a good linear relationship (R2=0.9902) in the concentration range of 1.0×10-8~1.0×10-3mol/L. By this method, the recovery of PENG residue ranges from 76% to 97% with relative standard deviation between 4.8% and 2.1%. The proposed SERS method can be effectively applied for determination of PENG residue in milk.