Gold has been shown to be the electrode substrate material of choice for the ASV determination of arsenic (III). Whilst the detection of As(III) at gold electrodes is still prone to interference, particularly from copper ions and organic matter in real samples, a variety of methods to overcome this problem have been developed. This has lead to the development of commercially available water testing kits such as those supplied by the company Wagtech International to the World Health Organisation for the in-field determination of arsenic in real watersampleswhichusegoldelectrodes[32].Recentlytheuse of nanoparticulate gold, supported on carbon substrates has been shown to reduce the interference from copper(II) ions and allow the trace determination of arsenic (III) [17,18,23].
The present study reports the electrochemical detection of arsenic using a random array of gold nanoparticles (GNPs) made by modifying a glassy carbon electrode with GNPs modified carbon nanotubes (AuCNTs). A large batch of carbon nanotubes is first electrolessly modified with gold nanoparticles and then a small amount of the resulting AuCNTs was deposited on a glassy carbon surface simply by putting a small drop of a dilute AuCNTs suspension in chloroform on to the surface followed by evaporation at room temperature. The coverage of the GNPs on the carbon nanotubes is such that the nanotubes themselves can simply be considered as a high area support and the electroactivity arises solely from the GNPs. Anodic stripping voltammetry was performed with nano molar arsenic standard additions in the form of linear sweep voltammetry (LSV) and square wave voltammetry (SWV) using an optimised system and a deposition time of 120s where a satisfactory LOD of 0.1±0.05gL−1 was obtained.