Johns Cameron, Yang Wenchu, Macka Miroslav, Haddad Paul R
Australian Centre for Research on Separation Science, School of Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia.
J Chromatogr A. 2004 Oct 1;1050(2):217-22.
A method for simultaneous separation and indirect detection of anions and cations by capillary electrophoresis (CE) is reported. An anodic electroosmotic flow (EOF) in excess of -100 x 10(-9) m2 V(-1) s(-1) was achieved by the addition of 0.1 mM didodecyldimethylammonium bromide (DDAB) to the background electrolyte (BGE). This high magnitude EOF enabled rapid co-EOF separation of inorganic anions and counter-EOF separation of inorganic cations having high electrophoretic mobilities. Single-end injection of the sample at the capillary inlet and detection near the capillary outlet was used. Indirect photometric detection of cations was accomplished using a cationic probe (imidazole), with counter-ionic (Kohlrausch) indirect detection being used for anions. A mixture consisting of chloride, bromide, nitrate, lithium, magnesium, sodium, calcium, potassium, and ammonium was separated in less than 3.5 min using a background electrolyte comprising 6 mM imidazole, 12 mM hydroxyisobutyric acid, 0.1 mM DDAB, 2 mM 18-crown-6 at pH 4.0, with indirect detection at 210 nm. The system was well suited to the separation and detection of inorganic cations, with limits of detection (LODs) in the range 0.92-4.65 microM and separation efficiencies from 44,400-208,5000 theoretical plates. By contrast, LODs for inorganic anions ranged from 6.66 to 11.43 microM, with separation efficiencies of 2500-26,300. Analytical potential of the method is discussed.
报道了一种通过毛细管电泳（CE）同时分离和间接检测阴离子和阳离子的方法。通过向背景电解质（BGE）中添加0.1 mM十二烷基二甲基溴化铵（DDAB），实现了超过 -100×10⁻⁹ m² V⁻¹ s⁻¹ 的阳极电渗流（EOF）。这种高强度的EOF能够实现无机阴离子的快速共EOF分离以及具有高电泳迁移率的无机阳离子的反EOF分离。采用在毛细管入口单端进样并在毛细管出口附近进行检测。使用阳离子探针（咪唑）完成阳离子的间接光度检测，阴离子则采用反离子（科尔劳施）间接检测。使用包含6 mM咪唑、12 mM羟基异丁酸、0.1 mM DDAB、2 mM 18 - 冠 - 6（pH 4.0）的背景电解质，在210 nm处进行间接检测，在不到3.5分钟内分离了由氯离子、溴离子、硝酸根离子、锂离子、镁离子、钠离子、钙离子、钾离子和铵离子组成的混合物。该系统非常适合无机阳离子的分离和检测，检测限（LOD）在0.92 - 4.65 μM范围内，分离效率为44,400 - 208,5000理论塔板数。相比之下，无机阴离子的LOD范围为从6.66到11.43 μM，分离效率为2500 - 26,300。讨论了该方法的分析潜力。
