SERS investigation and high sensitive detection of carbenicillin disodium drug on the Ag substrate.

The reliable and ultrasensitive detection of antibiotic drug residue is of great interest for environmental protection and human health. Herein, we propose a simple SERS strategy based on Ag nanoparticles (NPs) as substrate with the assistance of aggregation agent (MgSO4) for the SERS investigation and the high sensitive detection of antibiotic drug carbenicillin disodium (CBDM). The density functional theory calculation was performed for the assignment and identification of Raman bands of the CBDM molecule. The results indicate that the CBDM molecule is close to the Ag NP substrate surface through the carboxyl group. The CBDM molecules on Ag NP substrate exhibit the largest SERS enhancement, when the concentration of MgSO4 is 1 × 10-2 mol/L and the pH value of CBDM solution is 6. By this SERS method, the limit of detection of CBDM is 0.63 × 10-8 mol/L, which is lower than the standard of European Union for the maximum residue limit of antibiotic drug (1.2 × 10-8 mol/L). And, a quantitative detection method of CBDM can be established. There is a good linear relationship (R2 = 0.9908) in the concentration range of 1.0 × 10-8-1.0 × 10-3 mol/L. It proves that the proposed SERS method is a simple, rapid (within 6 min), reliable and highly sensitive scheme with a good reproducibility for the detection of CBDM. And, the proposed SERS strategy can also be applied for the high sensitive detection and identification of other antibiotic drug (penicillin).