毛细管电泳柱上络合分离、间接紫外检测重金属离子

Separation and Determination of Heavy Metal Ions by Capillary Zone Electrophoresis with Indirect UV Detection

采用弱络合剂乙醇酸,柱上络合,间接紫外检测毛细管区带电泳(CZE)技术对重金属离子Ba2+、Cr3+、Cd2+、Pb2+及可能存在的干扰离子进行了分离研究。通过对背景电解质种类和浓度、缓冲液pH、有机添加剂等的优化,确定了最佳分离体系为含12 mmol/L络合剂乙醇酸的10 mmol/L吡啶溶液作为背景电解质(pH 4.0)。在电压15 kV,压差进样68.95 kPa.s,260 nm间接紫外检测条件下,采用50 cm(45.5 cm)×50μm(I.D.)石英毛细管,重复性实验(n=9):迁移时间RSD≤1.37%,峰高RSD≤1.70%,峰面积RSD≤3.55%;Pb2+、Ba2+和Cd3+的检出限(S/N=3)为0.2 mg/L,Cr3+的检出限为0.08 mg/L;在检出限至10 mg/L范围内,各离子的浓度与峰面积线性相关系数好于0.998。该方法并应用于实际样品的分析。

In order to determine heavy metal ions in building and decorating materials, capillary zone electrophoresis with on-column complexation using glycolic, indirect UV detection was applied to the separation of Ba（ Ⅱ ） , Pb（ Ⅱ ） , Cd（ Ⅱ ） and Cr（Ⅲ）. The influence of carrier electrolyte parameters such as electrolyte, concentration and pH, as well as some operational parameters, was investigated and discussed. Under optimized conditions, the heavy metal ions were separated simultaneously along with some other alkali metal, alkaline earth metal and transition metal ions in a 10 mmol/L pyridine buffer （pH 4.0） eontaining 12 mmol/L glyeolic. The quantitative performanee of the method was stud-ied with indirect UV detection at 260 nm, 15 kV, 68.95 kPa·s injection, using a capillary of 50 cm （45.5 cm） × 50 μm （ I. D. ）. The relative standard deviations（ n = 9） of migration times, peak heights and peak areas for the four heavy metal ions were less than 1.37% , 1.70% and 3.55% , respectively. The detection limits for a signal-to-noise ratio of 3 were in 0. 08 mg/L for Cr（Ⅲ） and 0. 2 mg/L for other ions. All metals studied gave a linear relationship between peak area and concentration from the detection limits to 10 mg/L（ r≥0. 998）. Application of the method to the analysis of metal ions in paint sample was also demonstrated.