Determination of Thiourea in Flour and Noodles by Fluorescence Spectrometry Based on Fluorescence Resonance Energy Transfer between Pefloxacin and Gold Nanoparticles

Fluorescence resonance energy transfer between pefloxacin and gold nanoparticles (AuNPs) resulted in fluorescence quenching of pefloxacin. Because of forming strong Au-S bond between thiourea and AuNPs, pefloxacin was released from the surface of AuNPs, then the fluorescence of the system recovered. A method for the determination of thiourea by fluorescence spectrometry was established based on the above facts. Under optimized experimental conditions, linear relationship was found between fluorescence intensity of pefloxacin-AuNPs system and the concentration of thiourea in the range of 4.0×10^-7-5.0×10^-6mol·L^-1, with detection limit (3s) of 1.4×10^-7mol·L^-1. The proposed method was applied to determination of thiourea in flour and noodles, giving results in contency with those obtained by catalytic kinetic spectrophotometry, with relative standard deviation less than 4.0%, and values of recovery obtained by standard addition method were in the range of 92.5%-105%.