Objectives: To develop gold nanostructure on Pt substrate for detection of Hg(II) in
environment by DPASV technique. Its structure was characterized by SEM and electrochemical performance
was evaluated. The fabricated electrodes were used to measure Hg(II) samples in a concentration
range from 2 to 100 ppb.
Method: Gold nanoparticles (AuNPs) and AuNDs were deposited on platinum substrates by applying
potential of +0.50 V for AuNPs deposition and galvanostatic of -50 mA for AuNDs/Pt in a solution
20 mM HAuCl4, 10 mM KI, 5 mM NH4Cl and 0.5 M H2SO4.The electrochemical behaviors of
AuNPs/Pt and AuNDs/Pt were examined using CV in 5 mM K3[Fe(CN)6]/0.1 M PBS solution, pH = 7
and the detection of Hg(II) was performed by DPASV.
Results: The SEM images show that largest surface area was obtained at 120 s depositing time. Effective
surface areas (ESA) of AuNPs and AuNDs are about 1.39 and 5.19 times higher than electrode
geometric area. Calibration curves achieved with R2= 0.9978; 0.9975; 0.9973 and LOD= 0.55; 0.105
and 0.042 ppb for Au disk, AuNPs/Pt and AuNDs/Pt respectively. Reproducibility with ten measurements
of 10, 40 and 80 ppb of Hg(II), RSD (%) were 3.5, 2.8 and 1.5 respectively. No significant effect
on Hg(II) signals was found except CCu(II) with 100 times higher than CHg(II). Comparison with AAS,
data difference between the two techniques is acceptable, at only 4.34%.
Conclusion: LOD for Hg(II) detection by AuNDs/Pt achieved 0.042 ppb with linear range of 2.0–100
ppb. Combining with a laboratory constructed galvano-potentiostat, it can be used in on-site measurement.