Development of p-nitroaniline dithiocarbamate capped gold nanoparticles-based microvolume UV-vis spectrometric method for facile and selective detection of quinalphos insecticide in environmental samples

A simple and selective p-nitroaniline dithiocarbamate capped gold nanoparticles (p-NA-DTC-Au NPs) based colorimetric sensor was developed for the detection of quinalphos in water and food samples. The method was based on the color change of p-NA-DTC-Au NPs from red to blue with the addition of quinalphos to p-NA-DTC-Au NPs that caused a red-shift in their surface plasmon resonance (SPR) band from 522 to 694 nm due to the inter-particle coupling effect. Under the optimized conditions, a linear relationship between the absorption ratio (A(522)/A(694)) and quinalphos concentration was found in the range of 1.0-1000 mu M with correlation coefficient (R-2) of 0.982. The detection limit of quinalphos was 0.35 mu M, which is lower than the other analytical techniques. Moreover, the proposed nanosensor was successfully applied to the detection of quinalphos in environmental water, fruit and grain samples with good recoveries. (C) 2016 Elsevier B.V. All rights reserved.