Chitosan-stabilized gold nanoparticles decorated with a thiodiacetic acid nanoprobe for selective detection of arsenic(iii) in rice and water samples

Abstract

A sensitive and selective method for the detection of arsenic(III) (As³⁺) based on chitosan-stabilized gold nanoparticles (CS/AuNPs) decorated with a 2,2′-thiodiacetic acid (TDA) nanoprobe was developed and used to detect and indicate the contamination of rice, drinking water and environmental water samples. AuNPs were reduced and stabilized with CS and subsequently functionalized with TDA. As³⁺ interacted with the carboxylate group of TDA to form an As–TDA complex, inducing the aggregation of CS/AuNPs@TDA. The aggregation of CS/AuNPs@TDA was accompanied with a change in color from red to bluish purple and a shift in surface plasmon resonance wavelength from 525 nm to 645 nm. The response for the detection of As³⁺ was linear at concentrations from 10 to 1000 μg L⁻¹ with a limit of detection of 6.1 μg L⁻¹. The method exhibited selectivity toward As³⁺ among various cations (As⁵⁺, Cu²⁺, Fe³⁺, Fe²⁺, Hg²⁺, Al³⁺, Cr³⁺, Cd²⁺, Co²⁺, Ni²⁺, Pb²⁺ and Zn²⁺) and anions (Br⁻, Cl⁻, F⁻, SO₄²⁻, NO₃⁻ and PO₄²⁻). The CS/AuNPs@TDA nanoprobe was applied to detect As³⁺ in rice, drinking water and environmental water samples. The results were consistent with those obtained via inductively coupled plasma-optical emission spectrometry (ICP-OES). Satisfactory recoveries ranging from 88.22% to 105.74% (RSDs of 0.25–2.99%) were obtained from spiked samples.