RESUMO
This paper presents an electrochemical sensor for Cr(VI) (chromate ion) in water. A disposable screen-printed electrode was modified with gold nanostars (AuNSs) that were synthesized by Good's buffer method. Linear sweep voltammetry (LSV) was employed for the detection of Cr(VI) in 0.1 M sulfuric acid solution. The AuNSs are shown to provide higher current response to Cr(VI) than spherically shaped gold nanoparticles. The sensor gives the strongest response at a scan rate of 0.05 V (vs Ag/AgCl) and exhibits minimal interference from other electroactive species. The linear range extends from 10 to 75,000 ppb, and the limit of detection is 3.5 ppb. This is well below the provisional guideline value given by the World Health Organization. Excellent recoveries (ranging between 95 and 97%) were found when analyzing contaminated ground water samples obtained from a site situated in Wellesley, MA. Graphical abstract Schematic presentation of preparation of gold nanostars (AuNS) on carbon paste screen printed electrode (CPSPE) by drop casting and electrochemical detection of chromium (VI) using linear sweep voltammetry (LSV).
