固体汞电极溶出伏安法测定地下水示踪剂中的铜及实验应用

用易溶于水的金属盐类试剂作示踪剂,是岩溶地下水示踪试验中广泛采用的有效方法,通过野外现场测定人工示踪剂中的金属离子可以揭示岩溶地下水的运动特征.传统极谱法所用的液态汞操作不便,且容易造成环境污染.本文制作了固体汞电极,采用溶出伏安法测定地下水示踪剂中的铜,在地下水样品中加入醋酸一醋酸钠缓冲溶液,氯化钾溶液作为支持电解质,采用固体汞电极扫描,记录溶出曲线.实验了氯化钾溶液、醋酸-醋酸钠缓冲溶液用量对100 ng/mL铜标准工作溶液峰电流的影响,在选定最佳实验条件下,铜浓度在0 ～ 1000 ng/mL范围内与峰电流呈现良好的线性关系,相关系数大于0.999,方法检出限为0.58 ng/mL,加标回收率为96.4％ ～ 101.7％.地下水中可能存在的一些离子对测定不产生干扰.该方法应用于地下水示踪试验,铜的测定结果与极谱法基本吻合,且简单快速,适合野外现场测定,同时避免了极谱法液态汞的污染问题.

Application of Stripping Voltammetry with a Solid Amalgam Electrode for Determination of Copper in a Tracer and Groundwater Tracing Experiment

Using water-soluble metal salts as tracers, provides an effective method for karst groundwater tracing experiments, which reveal the motion law of karst groundwater by the instant determination of metal ions with artificial tracers in the field. Liquid mercury used in traditional polarography is inconvenient to operate and easily pollutes the environment. In this work, a solid amalgam electrode was made and used for the determination of copper ion in groundwater tracer by stripping voltammetry, in which method the buffer solution of HAc-NaAc was added to the groundwater sample and potassium chloride solution was used as a supporting electrolyte, while the solid amalgam electrode sweeping was employed and the stripping diagram was recorded. Effects of the amount of potassium chlorate solution and HAc-NaAc buffer solution on peak current with a concentration of 100 ng/mL copper standard solution were studied. Copper concentration in the range of 0-1000 ng/mL demonstrated a good linear relationship with the peak current under the selected optimal conditions. The correlation coefficient was greater than 0.999, the detection limit was 0.58 ng/mL and the addition standard recoveries were 96.4%-101.7%. The results were not interfered with by the ions possibly existing in groundwater. When applied to groundwater tracing experiments, stripping voltammetry results for copper ions agree well with those obtained by polarography. This method provides a simple and rapid procedure, which is suitable for field spot determination while avoiding pollution by liquid mercury.