Determination of Penicillin G Sodium Residue in Milk by Surface Enhanced Raman Spectrometry

The normal Raman spectrum signal of penicillin G sodium (NaBP) solution was weak. 20 μL of concentrated silver nanoparticles (AgNPs) prepared were mixed with NaBP solution in different concentrations (1×10^-9-1×10^-1mol·L^-1), and surface enhanced Raman spectrometry (SERS) signal of the mixture obtained was significantly enhanced. 8 μL of 1×10^-2mol·L^-1 magnesium sulfate solution was added into the above mixture, and the SERS enhancement effect of NaBP was the best. Therefore, a method for determination of NaBP by SERS with AgNPs as substrate and magnesium sulfate as coagulant was proposed, and this method was applied for determination of NaBP residue in milk. As shown by the results, linear relationship between the logarithm of NaBP concentration and the corresponding SERS signal intensity was found in the range of 1×10^-8-1×10^-3mol·L^-1, with detection limit (3s/k) of 8.2×10^-9mol·L^-1. Test for recovery was made by standard addition method, giving results in the range of 80.0%-96.0%, with RSDs (n=5) of the determined values in the range of 2.3%-6.5%.