Quantitative Analysis of Amoxicillin Residues in Foods by Surface-Enhanced Raman Spectroscopy

Amoxicillin is one of the most widely used antibiotics for food-producing animals and human beings. Amoxicillin residue in food-producing animals has become a growing concern for consumers because it has been proven to show potential carcinogenic, teratogenic, and mutagenic effects at a high-dose level in clinical use. So there is an urgency to develop a rapid, simple, and accurate detection method for amoxicillin residue in animal foods. In this study, surface-enhanced Raman spectroscopy (SERS) coupled with gold nanoparticles was used for the rapid analysis of amoxicillin. Density functional theory (DFT) calculations were conducted with Gaussian 03 at the B3LYP level using the 6-31G(d) basis set to analyze the assignment of vibrations. Results showed that the theoretical Raman spectra of amoxicillin were completely consistent with its experimental spectra. Gold nanoparticles used as a SERS substrate can significantly increase spectra signals of amoxicillin, and acidic pH can improve its characteristic peaks' shape and SERS sensitivity. Under optimum pH (pH 2), the detection limit could reach the level of 1 mu g/mL in case of distilled water as solvent. Quantitative analysis of amoxicillin residues in foods revealed that the SERS technique with gold nanoparticles was sensitive and of a good stability and linear correlation. It was well suited for rapid analysis of amoxicillin residue in a great deal of food samples.