电化学预处理玻碳电极示差脉冲伏安法测定水中痕量铅

Determination of Trace Amount of Lead in Water by Differential Pulse Voltammetry with Chemically Pretreated Glassy Carbon Electrode

将玻碳电极在pH 4.0乙酸盐缓冲溶液中,于电位+1.8 V(vs.SCE)处阳极氧化,然后在-0.8^+1.0 V电位范围内循环扫描,进行预处理。研究了铅离子在预处理玻碳电极上的电化学行为,结果表明:与未修饰的电极相比,Pb2+在该修饰电极上有一对氧化还原峰,峰电位分别为-0.57 V和-0.68 V(vs.SCE),且峰电流大大提高。据此提出了示差脉冲伏安法测定Pb2+的方法。在优化的试验条件下,氧化峰电流与Pb2+的浓度在3.2×10-7~4.2×10-5mol.L-1范围内呈线性关系。检出限(3S/N)为3.2×10-8mol.L-1。应用该预处理电极测定水样中微量铅,加标回收率在93.8%~104.7%之间,相对标准偏差(n=6)在3.1%~4.3%之间。

Glassy carbon electrode（GCE） was pretreated by anodic oxidation at ＋1.8 V（vs.SCE） and scanned in the potential range of-0.8 to ＋1.0 V in acetate buffer solution of pH 4.0.The electrochemical behavior of Pb2＋ ion at this pretreated GCE was studied.It was found that Pb2＋ ion showed a pair of oxidation peak and reduction peak at the pretreated GCE,with their potentials at-0.57 V and-0.68 V（vs.SCE） respectively.The peak current was raised greatly as compared with the reaction at the bare GCE.Based on these findings,a sensitive method for determination of Pb2＋ ion by differential pulse voltammetry was proposed.Linear relationship between values of peak current and concentration of Pb2＋ ion was obtained in the range of 3.2×10-7-4.2×10-5mol·L-1,with detection limit（3S/N） of 3.2×10-8mol·L-1.The proposed method was applied to the determination of trace amount of lead in water samples,giving values of recovery and RSD′s（n=6） in ranges of 93.8%-104.7% and 3.1%-4.3%,respectively.