砷酸根和硒酸根的毛细管电泳分离

Separation of Arsenate and Selenate with Capillary Zone Electrophoresis

在铬酸盐和硼酸盐溶液中,以十六烷基三甲基溴化铵（CTAB）为电渗流改性剂,通过添加有机添加剂甲醇,成功地分离了砷酸根、硒酸根及常见酸根离子.优化分离条件发现,采用210 nm直接检测砷酸根比在260 nm处间接检测其检出限更低,而且可以减少大量Cl^-的干扰.迁移时间重复性的相对标准偏差（RSD）不大于3.0%,当信噪比（S/N）为2时,在260 nm处,HAsO4^2-与SeO4^2-的检出限分别为0.019 mg/L和0.078mg/L;在210 nm处,HAsO4^2-检出限可达0.004 3 mg/L.加标回收率均在95%～108%之间,满足定量要求.但NO3^-会干扰HAsO4^2-的定量分析.

A method was developed for the separation and analysis of arsenate and selenate by capillary zone electrophoresis（CZE） using chromate and borate as electrolyte buffer. By adding a certain amount of methanol to the background electrolyte （BGE） and by using cationic surfactant of cetyltrimethylammonium bromide （CTAB） as electro-osmotic flow modifier, the electrophoretic peaks of arsenate and selenate were well separated. The detection limit of HAsO4^2- obtained with direct UV detection at λ210 nm could be lower than that obtained with indirect UV detection at λ260 nm. The relative standard deviations （n =9） of migration times for HAsO4^2- and SeO4^2- were both less than 3.0%. The detection limits （S/N=2） were 0. 019 mg/L for HAsO4^2- and 0. 078 mg/L for SeO4^2- at λ260 nm, but 0. 004 3 mg/L for HAsO4^2- at λ210nm. The recovery range was 95% - 108%. Nitrate ion would interfere the analysis of HAsO4^2-.