Image Digitization of Colorimetric Detection of Acephate Based on Its Complexation with Citrate-Capped Gold Nanoparticles

Abstract

Acephate (Ac), an organophosphate (OP) insecticide, is very harmful to human and the environment. Conventional techniques of detection are sensitive and selective but relatively time-consuming, expensive, and require trained personnel. This paper describes the use of an image processing technique to digitize the red values (RVs) of the colour image of Ac-capped gold nanoparticles (Ac-Cit-AuNPs) complex captured using a digital microscope to improve the detection accuracy and precision. The formation of the suspension was characterised using laser test, ultraviolet-visible spectrophotometer (UV-Vis), high-resolution transmission electron microscope (HRTEM), and Fourier Transform infrared spectroscope (FTIR). The linear regression analysis revealed that the detection sensitivity improved as the smaller gold nanoparticles were used. For quantitative measurement using image processing, a good linear relationship (R2 = 0.9905 and 0.9924) for Cit-HAuNPs and Cit-MAuNPs, respectively, between the concentration of Ac and average red values was obtained in the range of 0–8 mM. The limit of detection (LOD) for Ac was found to be 0.3 mM and 0.4 mM for Cit-MAuNPs and Cit-HAuNPs, respectively.

Optimisation of a gold nanoparticle-based aptasensor integrated with image processing for the colorimetric detection of acephate using response surface methodology

“…63 Detection accuracy of Ac was improved using a colorimetric sensor array consisting of citrate-capped gold nanoparticles (Cit-AuNPs), which was coupled with an applied image processing. 64 Ma et al (2021) developed an AuNPs based colorimetric sensor for the detection of pesticides, in which the color changes of the aggregated AuNPs were captured using a smartphone camera, and the images were processed to obtain average RGB (red, green, and blue) values using selfdeveloped soware. 65 Recently, Qu et al (2020) evaluated the effect of pH and ionic strength (through the addition of common salt (NaCl)) on the sensitivity and selectivity of colorimetric detection towards ametryn.…”