SERS strategy based on the modified Au nanoparticles for highly sensitive detection of bisphenol A residues in milk

Bisphenol A (BPA) is a highly toxic chemical, and its residue in milk product is threatening people's health due to its possible leaching from the packagings and cans with BPA coating. In this work, halides modified Au nanoparticles (NPs) as the modification substrates were first designed for rapid and sensitive determination of BPA residue in real milk by SERS method with the assistance of aggregation agents (Zn²⁺). It can be concluded that Au NPs modification substrate with assistance of the aggregation agent can remarkably improve the detection sensitivity of BPA residue, which can significantly enhance the SERS signal of BPA and achieve the trace-level detection of BPA residue. Under the optimal conditions, the limit of detection of BPA residue can be as low as to 4.3 × 10^-9mol/L (equal to 0.98 × 10^-3mg/kg), which is much less than the standard of European Union (0.6mg/kg). And, there is a good linear relationship (R² = 0.990) between the intensity of SERS signal and the logarithm of BPA concentration in the range of 1.0 × 10^-8-1.0 × 10^-3mol/L. By this method, the recovery of BPA residue ranges from 89.5% to 100.2% with relative standard deviation between 4.6% and 2.7%. The proposed SERS method proves to be reliable, highly sensitive and possesses good reproducibility, which is very promising for sensitive detection of bisphenols residue in foodstuff.