电解脱锡-电感耦合等离子体原子发射光谱法测定镀锡板镀层中铅

在盐酸介质中,以甘汞电极为参比电极,铂金丝为辅助电极,试样为工作电极进行电解脱锡。观察电压与时间的电解曲线变化,确定了镀锡层剥离的电流密度为5 mA/cm²;通过溶液浓缩试验,确定溶液的加热温度为500 ℃、浓缩时间为45 min;选择Pb 220.353 nm作为分析线,基体匹配法绘制校准曲线可消除基体效应的影响,测定脱锡溶液中铁量并扣除铁对铅的干扰量,最终通过计算得到镀层中铅量,从而建立了电解脱锡-电感耦合等离子体原子发射光谱法(ICP-AES)测定镀锡板镀层中铅的方法。在50 mL盐酸溶液中,铅的质量在2.50～15.0 μg范围内与发射强度呈线性,相关系数r=0.999 3。方法中铅的检出限为0.24 μg/g。方法用于测定镀锡板镀层中铅,结果的相对标准偏差(n=6)小于3.0%;加标回收率为97%～104%。

Determination of lead in tin plating layer by inductively coupled plasma atomic emission spectrometry after electrolytic detinning

The electrolytic detinning was performed in hydrochloric acid medium using calomel electrode as reference electrode, platinum wire as auxiliary electrode and sample as working electrode. The change of electrolytic curve between voltage and time was observed. The electric current density for stripping of tin plating layer was 5 mA/cm². The heating temperature of 500 ℃ and concentration time of 45 min were obtained by solution concentration experiments. Pb 220.353 nm was selected as the analytical line. The influence of matrix effect could be eliminated by preparing the calibration curve using matrix matching method. The content of iron in detinning solution was determined, and the interference amount of iron on lead was deducted. Finally, the content of lead in plating layer was obtained by calculation. Consequently, the determination method of lead in tin plating layer by inductively coupled plasma atomic emission spectrometry (ICP-AES) after electrolytic detinning was established. In 50 mL hydrochloric acid solution, the mass of lead in range of 2.50-15.0 μg was linear to the emission intensity with correlation coefficient of 0.999 3. The detection limit of lead in this method was 0.24 μg/g. The proposed method was applied to the determination of lead in tin plating layer. The relative standard deviations (RSD, n=6) were less than 3.0%, and the recoveries of standard addition were between 97% and 104%.