采用毛细管电泳电堆集富集技术分离与测定雪样中的痕量阳离子

Separation and Determination of Trace Cations from Snow Sample by Capillary Electrophoresis With Sample Stacking Mode

以咪唑为背景电解质,以α-羟基异丁酸和18-冠醚-6为络合剂,采用毛细管离子电泳间接紫外法,研究了雪样中痕量NH^+_4、K^+、Ca^(2+)、Na^+、Mg^(2+)分离与测定的方法.通过向缓冲液中加入甲醇,使Ca^(2+)、Na^+迁移顺序发生反转,有利于在Ca^(2+)的浓度较高时少量Na^+、的测定.采用电堆集富集技术,各离子的检测限达1×10^(-7)mol/L.以Li^+作为内标,采用标准加入法对雪样中的痕量阳离子进行了测定.

A method for the separation and determination of trace NHT , K+ , Ca2+ , Na+ , Mg2+ insnow sample by capillary electrophoresis using imidazole as background electrolyte, α-hydioxyisobutyricacid and 18-crown-6 as complexing agents with sample stacking enrichment technique was described. Organic additive (methanol) was added to the buffer to improve the resolution of cations. The Na+ could be determined accurately in the presence of high concentration of Ca2+ because the peaks of Ca2+ and Na + cross-over occured when the buffer contained 20% methanol. The detection limits of NH4+ , K+ ,Ca2+ , Na+ , Mg2+ ,Li+ were 1×10-7 mol/L with sample stacking injection. Using relative peak areasof each ion to Li+ as response, the contents of NH4+, K+ , Na+ , Ca2+ , Mg2+ in snow sample were determined with standard addition method.