Abstract
A modified glassy carbon electrode (Aufilm/GCE) using a gold film was constructed for determination of chromium(VI) in real water samples. A GCE was immersed in HAuCl4 solution (10-3 M) and the thin layer of gold was electrodeposited for 10 min at −0.4 V (vs. Ag/AgCl). Compared with only GCE, a strong affinity between chromium and gold species was observed with an increase in Cr(VI) signal. The type of supporting electrolytes, electrodeposition time, scan rate, pH, modulation time and the modulation amplitude were optimized through differential pulse-anodic stripping voltammetry (DP-ASV). A calibration graph acquired using the accumulation time of 120 s with a sensitivity of 1.3 × 10-2 μA/μgL-1 was linear in the range of 10-120 μg L-1. A low detection limit of 5.5 μg/L Cr(VI) and a strong correlation coefficient R2 = 0.9971 were obtained under the optimal experimental conditions. Signals were reproducible and exhibited a relative standard deviation of ±4.5%. A modified sensor was employed to determine the Cr(VI) content in the sewage water samples.
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