基于场放大进样-电动反平衡扫集的毛细管电泳富集分离系统的研究及其在铁矿石检测中的应用

利用EDTA作为捕获载体,结合场放大进样技术,建立了一种基于场放大进样-电动反平衡扫集在线双重富集的毛细管电泳富集分离新体系并用于铁矿石中锰、铬、铅、铜、镍和钴6种重金属元素的检测。金属离子首先通过场放大进样堆积在水塞与高电导缓冲溶液的界面上,然后被迎面而来的带负电荷的EDTA捕获,样品区带被进一步压缩,实现信号的双重放大。通过控制电渗流使金属-EDTA螯合物处于准静止状态,实现大体积进样及检测信号的高度放大。通过15 kV电动进样50 min双重富集后,灵敏度比常规毛细管电泳提高了1.2×10⁴～8.5×10⁴倍,铁矿石中6种重金属离子的检出限为0.06~0.32 μg/L。用建立的方法测定铁矿石中锰、铬、铅、铜、镍和钴,测定值与ICP-MS法测定值之间的相对误差在5.3%～11.5%之间。

Study on capillary electrophoresis enrichment and separation system based on field magnified injection-electric counter balance purge-trap and its application in iron ore detection

Combining with field magnified injection technology, the determination of six heavy metal elements (manganese, chromium, lead, copper, nickel and cobalt) in iron ore by on-line dual-enrichment capillary electrophoresis enrichment and separation system based on field magnified injection-electric counter balance purge-trap was established using EDTA as trap carrier. The metal ions were firstly accumulated on the interface between water plug and high-conductivity buffer solution via field magnified injection, and then trapped by oncoming negative charged EDTA. The sample region was further compressed, realizing the dual amplification of signal. By controlling the electro-osmotic flow, the metal-EDTA chelate was under quasi-static condition. Thus, the large volume injection and significant amplification of detection signal were realized. After dual-enrichment at 15 kV for 50 min, the sensitivity increased by 1.2×10⁴-8.5×10⁴ times than that of conventional capillary electrophoresis. The detection limits of six heavy metal ions in iron ore were 0.06-0.32 μg/L. The proposed method was applied to the determination of manganese, chromium, lead, copper, nickel and cobalt in iron ore. The relative error between determination results of proposed method and those of ICP-MS was between 5.3 %-11.5 %.