Gold Nanoparticle Dropped Titania Microsphere Hybrids as an Enhanced Sensitive Material for Stripping Voltammetry Determination of As (III)

Abstract

A simple, efficient electrochemical assay based on gold nanoparticle dropped TiO 2 microsphere (Au/TiO 2 ) hybrids was developed for the highly sensitive and selective determination of Arsenic (As (III)) by square wave anodic stripping voltammetry (SWASV). An Au/TiO 2 modified glassy carbon electrode (Au/TiO 2 /GCE) possessed a three-dimensional porous structure and exhibited a high active surface area and excellent electron transfer properties. Due to the synergy effect of Au/TiO 2, Au/TiO 2 /GCE greatly enhances the selectivity, sensitivity, and stability of electrodes with respect to the reduction time and composition of the electrodes compared to gold nanoparticle modified GCE (Au/GCE) and TiO 2 modified GCE (TiO 2 /GCE) for detection As (III). The experimental conditions with respect to reduction time and electrolyte were optimized to maximize the sensitivity of the measurement. Under optimal conditions, the SWASV peak current for As (III) concentration was excellent in the range of 1 × 10 −7 to 8 × 10 −6 M. The limit of detection (LOD) of this sensing system was 0.04 μM. Simultaneously, the sensing system's good repeatability and stability prevents the effects of interfering species, which is suitable for As(III) determination in real samples.Arsenic is a highly toxic element and a relatively widespread water pollutant related to different diseases in some countries. 1-7 Investigation has shown that continued consumption of elevated levels of arsenic will caused skin, 8 bladder, kidney, liver, and lung cancers, 9 heart disease, and stillbirth. 7,10,11 Inorganic arsenic exists in ground water mainly as AsO 2− (As (III)) and AsO 4 3− (As (VI)). The former is about 50 times more poisonous than arsenate ions due to its reaction with enzymes in the human metabolism system. 7,10 The maximum As (III) concentration allowed in drinking water as set by the World Health Organization (WHO) is 0.01 μg/L (10 ppb). 12,13 Multiple methods have been used for measuring the level of As (III), 14,15 including atomic absorption spectrometry, 16-20 spectrophotometric, 21-23 fluorescence spectroscopy, 24,25 and inductively coupled plasma-mass spectrometry (ICP-MS). 26-28 These methods were successful in detecting As (III) at sub ppm to sub ppb levels and suitable for laboratory conditions, 14 but their reproducibility is poor and they require timeintensive procedures for pre-separating, 15,29 which requires expensive and sophisticated instruments. Because the presence of As (III) in food or water above a certain level presents a serious threat to public health, it is urgent to develop a simple, low cost, easy operation, highly sensitive, and selective analytical method for determination of trace amounts As (III). 15 Electrochemical methods have received a great deal of attention as a promising source 2 due to the inexpensive instrumentation, portability, extremely high sensitivity, fast response, and low detection limit. 9 Signal amplification is the most popular strategy, and has been extensively used for the development of ultr...

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