Amide-functionalized humic acids (AHA) was synthetized by two step reactions, in which humic acids first reacted with thionyl chloride(SOCl2) and then reacted with ammonia liquor. The AHA was characterized by Fourier transform infrared (FTIR) spectra and elemental analysis method. The reaction properties between AHA and mercury ions(I,II) were investigated at an AHA chemically modified carbon paste electrode (AHACMCPE) using cyclic voltammetry (CV) and linear sweep stripping voltammetry (LSSV). Moreover, the binding behavior of numerous other ions at the AHA-CMCPE was also tested. In an open circuit, Both HgI and HgII were accumulated from a stirred 0.1M H2SO4 solution onto the AHACMCPE. The subsequent electrochemical measurement was performed in another clean supporting electrolyte of 0.5M H2SO4. Factors affecting the accumulation and electrode reaction steps were investigated and an optimized procedure for quantifying mercury was developed. Under optimized conditions, a calibration plot for mercury concentration in the range 4.98

The underpotential deposition (UPD) of antimony(Ⅲ) on gold electrode was studied by using cyclic voltammetry (CV). Based on the excellent electrochemical properties of the Au/Sb UPD system, a new method for determination of antimony was developed. In this case, a more sensitive lectroanalytical technique, 1.5th order differentialanodic stripping voltammetry (1.5th ODASV), was used. A solution of 0.1 mol/L HCl was selected as the supporting electrolyte. Factors affecting the Sb(Ⅲ) UPD and stripping steps were investigated and an optimized analytical procedure was proposed. The calibration plots for Sb(Ⅲ) concentration in the range 1.25×10-8-3.38×10-7 mol/L were obtained. A detection limit of 2.1×10-9 mol/L was found for a 120 second electrochemical deposition at 0.100 V while the solution was stirred magnetically at a speed of 300 rpm. For 9 successive determinations of 2.5×10-8 mol/L Sb(Ⅲ), relative standard deviations, RSD, of 0.55% was obtained. The developed method was applied to antimony determination in ore samples.

An ethylenediamine fixed humic acid preparation (EHA) was synthesized by the interaction between the etheride of humic acid(HA) and ethylenediamine. The EHA was characterized by Fourier transform infrared spectrometry and elemental analysis, and employed to prepare a chemically modified electrode. Based on EHA-containing carbon paste electrode, the accumulation and electrochemical behavior of gold(III) were investigated by cyclic voltammetry and differential pulse stripping voltammetry (DPSV). The proposed measurement involves a medium exchange procedure in which the preconcentration step was accomplished in a solution of 0.35 M HCl and the subsequent electrochemical step performed in a supporting electrolyte of 0.8 M HCl. The oxidizing current (I'pa2) obtained by DPSV was proportional to the concentration of the Au(III) ion in a range of 3.5×10-6～5.1×10-8 M. The sensitivity and selectivity of the proposed method are obviously better than that of results obtained by using a chemically modi®ed carbon paste electrode of ordinary HA.

A chemically modified carbon paste electrode was prepared by incorporating appropriate amounts of sodium humate(NaA). Palladium(II) was selectively accumulated in a solution of Britton-Robinson(B-R) buffer (pH 2.8) onto the electrode surface in open circuit mode. The subsequent electrochemical measurement was carried out by cyclic voltammetry (CV) and linear sweep anodic stripping voltammetry (LSASV) in a supporting electrolyte of 1.0 M HCl. The obtained oxidation currents (Ipa1 and Lpa2) were proportional to the Pd(II) concentration in the range of 4.7

The eyclie voltammetry (CV) and the square-wave technique were used for the investigations of thallium (I) underpotential deposition (UPD) on the silver electrode. A solution of 10 mmol/L HClO4+10 mmol/L NaCl was selected as the supporting electrolyte. The calibration plots for Tl(I) concentration in the range of 2