Separation, identification and fast determination of organophosphate pesticide methidathion in tea leaves by thin layer chromatography–surface-enhanced Raman scattering

Abstract

In this work, a fast, sensitive and convenient method for the on-site separation, identification and determination of organophosphate pesticide methidathion in tea leaves was reported, by the use of thin layer chromatography (TLC) in combination with surface-enhanced Raman spectroscopy (SERS). Five different organophosphate pesticides have been successfully separated and identified. Factors that affect the SERS detection sensitivity of methidathion, such as the brand of TLC plate, material and concentration of metallic nanoparticles (NPs), have been examined. It is found that the limit of quantification for methidathion is 0.1 ppm. Spiked tea samples of different kinds and brands containing methidathion at the ppm level have been tested, with recovery rates in the range of 86–113%. The proposed method for the fast on-site determination of pesticide may help to address food safety concerns in the general public.