A novel metastable state nanoparticle-enhanced Raman spectroscopy coupled with thin layer chromatography for determination of multiple pesticides

A novel and highly sensitive metastable state nanoparticle-enhanced Raman spectroscopy (MSNERS) was reported in this work, which employed an amphiphilic polymer polyurethane-Ag nanoparticle (AgNPs) as the MSNERS substrate. Polyurethane could form micelle to incorporate nanoparticles and analytes, where targets could be in close contact with the metal surface, which was effective for further enhancing the detection sensitivity. Time-dependent visible absorption spectra and time-dependent Raman spectra indicated that polyurethane could greatly enhance the stability of AgNPs aggregates during the volatilization process, which was a great improvement of MSNERS substrate. Combining this MSNERS substrate with the rapid separation method of thin layer chromatography (TLC), this TLC-MSNERS was successfully applied to analyze mixed pesticides on fruit skin and the detection limits of thiabendazole, triazophos and phosmet were 0.02 μg/mL, 0.8 μg/mL, and 0.6 μg/mL, respectively. It enhanced 1 order of magnitude the signals of analytes in comparison to that of traditional TLC-SERS method.