将纯石墨电极经三氧化二铝抛光与浓硝酸和浓硫酸(1+1)混合酸使其极性化,之后于1 g·L-1聚氯乙烯(PVC)环己酮溶液10 μL中浸渍片刻,取出,用红外灯照射烘干30 min,冷却后,将电极置于含有哌嗪、K3PO4及二甲基甲酰胺(DMF)(2∶1∶8)的混合液中使其反应;最后在氢氧化钠存在下与二硫化碳反应,用水洗至中性,即制成修饰有二硫代氨基甲酸螯合树脂的石墨电极,将其用于银的测定.与未修饰的电极相比此电极具有较高的灵敏度和较好的选择性,在1.0×10-8~1.0×10-5mol·L-1范围内,峰电流与浓度呈线性关系,检出限为5.0×10-9mol·L-1.

To prepare the modified electrode,pure graphite electrode was polished with Al2O3 and polar-activated with an acid mixture of conc.HNO3 and conc.H2SO4 in ratio of 1 to 1.It was then soaked for a moment in 10 μL of 1 g·L-1 solution of PVC in cyclohexanone.After taking out from the solution and dried for 30 min under IR-radiation,the electrode was reacted in a solution containing piperazine,K3PO4 and DMF in the ratio of 2 to 1 to 8.Finally the electrode was reacted with CS2 in the presence of NaOH,and washed with water to neutrality.Better sensitivity and selectivity were obtained by the modified graphite in the determination of Ag+-ion,as compared with the unmodified electrode.The optimum conditions for the determination were described as follows:base solution 1.0 mol·L-1 KCl,acidity pH 1.7,time of enrichment 15 min,rate of scanning 100 mV·s-1.Linear relationship between the peak current (ip) and concentration of Ag+-ion was kept in the range of 1.0×10-8-1.0×10-5mol·L-1 with a detection limit of 5.0×10-9mol·L-1 of Ag+ ion.