Voltammetric detection of silver in commercial products on boron doped diamond electrode: stripping at lowered potential in the presence of thiosulfate ions

摘要

Bare boron-doped diamond electrode (BDDE) was applied for investigation of deposition/stripping processes of silver ions in various supporting electrolytes. The highest signal was observed in 0.1 mol dm(-3)HNO(3). Detection of silver ions is also possible in 0.1 mol dm(-3)Na(2)S(2)O(3)where Ag(+)is strongly complexed as [Ag(S2O3)(2)](3-). Though the sensitivity is 100 times lower, the potential of anodic dissolution of silver is significantly shifted towards the negative values. This shift might be useful for solving of some interferences which may occur in the detection process. After preliminary cyclic voltammetry, the analytical performance was studied by differential pulse anodic stripping voltammetry (DPASV) and square-wave anodic stripping voltammetry. Deposition potential of - 0.18 V vs. Ag/AgCl and deposition time of 240 s were selected as optimum DPASV parameters. The lowest detection limit of 2.0 x 10(-10) mol dm(-3)was achieved with DPASV in HNO3. Negligible effect of possible interferents on Ag response proved to be a good selectivity of method. The proposed method after validation was also applied to real samples analysis of some commercial products with complex matrix. The obtained results are statistically identical with data declared by manufacturer and gained by independent technique, making this method suitable for commercial product control.