流动注射-离子选择电极电位法测定循环冷却水中痕量铜

Determination of trace copper in circulating cooling water based on flow-injection and ion selective electrode technology

为了监测热交换器铜管的腐蚀情况，建立了一种能快速、自动测定循环冷却水中痕量Cu^2＋的流动注射离子选择电极法（FIA—Cu^2＋／ISE）。在研究过程中，对FIA—Cu^2＋／ISE系统的各种影响因素，如混合盘管长度、载流流量、进样量、干扰物质、总离子强度调节剂（TISAB）中Cu^2＋。含量、TISAB的浓度和pH及流量等进行了考察和优选，得到的最佳参数为：混合盘管长度为40cm，超纯水载流流量为2．3mL／min，TISAB流量为0．86mL／min（pH3．5），TISAB为0．4mol／L的KNO3，注入时间为90S，采样时间为30S，进样量为650μL；本方法测定Cu^2＋的线性范围为2．6～80Mg／L，分析速度为30样／h，回收率在99％～104％之间；用20ug／L和40μg／L的Cu^2＋标准溶液进行精密度试验，得到的相对标准偏差分别为3．9％，1．3%（n=11）。方法检出限为2．6μg／L。该法用于测定某电厂循环冷却水中痕量Cu^2＋，测定结果和标准加入法以及国家标准（GB）法的测定结果相一致。

For the purpose of monitoring corrosion state of copper tubers in the heat exchangers, a novel method for rapid and automatic determination of trace-level copper ion （Ⅱ） in circulating cooling water was proposed on the basis of flow injection analysis and ion selective electrode technology （FIA- Cu^2＋/ISE）. In the research, various influence factors to the FIA-Cu^2＋/ISE system were investigated and optimized, including the length of mixture coil, the flow rate of carrier, sampling volume, interfering substances, the concentration of copper ion （Ⅱ） in the total ion strength adjust buffer solution （TISAB）, pH value, flow rate and the concentration of TISAB. The optimal parameters were as follows： the length of mixture coil, 40 cm; the flow rate of ultra-purified water to be used as carrier, 2.3 mL/min; flow rate ,0. 86 mL/min; concentration of TISAB, 0.4 mol/L KNO3 （pH 3.5） ; loading and injecting time, 30 s and 90 s; sampling volume, 650 μL. The linear range of the system was 2.6-80 μg/L Cu^2＋. The detection limit was found to be Cu^2＋ with the 2.6 μg/L. The analysis speed was 30 samples per hour, and the recovery was in range of 99%-104%. The reproducibility test was conducted by using standard solutions of 20 μg/L and 40 μg/L, with the relative standard deviations （n= 11） of 3.9% and 1.3%, respectively. Through determining the concentration of copper in circulating cooling water from some power plants, it was discovered that results obtained by using this system was consistent with those of the standard addition method and the China standard method for analyzing trace-level copper ion.