Laboratory of Bioseparation and Analytical Biochemistry, State Key Laboratory of Microbial Metabolism, School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
Talanta. 2012 Jun 15;95:42-9. doi: 10.1016/j.talanta.2012.03.045. Epub 2012 Mar 29.
In this paper, a moving neutralization boundary (MNB) electrophoresis is developed as a novel model of visual offline sample stacking for the trace analysis of heavy metal ions (HMIs). In the stacking system, the cathodic-direction motion MNB is designed with 1.95-2.8mM HCl+98 mM KCl in phase alfa and 4.0mM NaOH+96 mM KCl in phase beta. If a little of HMI is present in phase alfa, the metal ion electrically migrates towards the MNB and react with hydroxyl ion, producing precipitation and moving precipitation boundary (MPB). The alkaline precipitation is neutralized by hydrogen ion, leading to a moving eluting boundary (MEB), release of HMI from its precipitation, circle of HMI from the MEB to the MPB, and highly efficient visual stacking. As a proof of concept, a set of metal ions (Cu(II), Co(II), Mn(II), Pb(II) and Cr(III)) were chosen as the model HMIs and capillary electrophoresis (CE) was selected as an analytical tool for the experiments demonstrating the feasibility of MNB-based stacking. As shown in this paper, (i) the visual stacking model was manifested by the experiments; (ii) there was a controllable stacking of HMI in the MNB system; (iii) the offline stacking could achieve higher than 123 fold preconcentration; and (iv) the five HMIs were simultaneously stacked via the developed stacking technique for the trace analyses with the limits of detection (LOD): 3.67×10(-3) (Cu(II)), 1.67×10(-3) (Co(II), 4.17×10(-3) (Mn(II)), 4.6×10(-4) (Pb(II)) and 8.40×10(-4)mM (Cr(III)). Even the off-line stacking was demonstrated for the use of CE-based HMI analysis, it has potential applications in atomic absorption spectroscopy (AAS), inductively coupled plasma-mass spectrometry (ICP-MS) and ion chromatography (IC) etc.
本文开发了一种移动中和边界（MNB）电泳，作为痕量重金属离子（HMIs）离线样品堆积的新型可视化模型。在堆积系统中，设计了阴极方向运动的 MNB，相 alpha 中为 1.95-2.8mM HCl+98mM KCl，相 beta 中为 4.0mM NaOH+96mM KCl。如果相 alpha 中存在少量 HMIs，金属离子会向 MNB 电迁移，并与氢氧根离子反应，生成沉淀并移动沉淀边界（MPB）。碱性沉淀被氢离子中和，导致移动洗脱边界（MEB），HMIs 从沉淀中释放，HMIs 从 MEB 循环到 MPB，实现高效的可视化堆积。作为概念验证，选择了一组金属离子（Cu(II)、Co(II)、Mn(II)、Pb(II)和 Cr(III)）作为模型 HMIs，选择毛细管电泳（CE）作为实验分析工具，证明了基于 MNB 的堆积的可行性。结果表明：（i）实验证明了可视化堆积模型；（ii）MNB 体系中存在可控制的 HMIs 堆积；（iii）离线堆积可实现超过 123 倍的预浓缩；（iv）通过开发的堆积技术，可同时堆积五种 HMIs 进行痕量分析，检测限（LOD）分别为：3.67×10(-3)（Cu(II)）、1.67×10(-3)（Co(II)）、4.17×10(-3)（Mn(II)）、4.6×10(-4)（Pb(II)）和 8.40×10(-4)mM（Cr(III)）。即使离线堆积被证明可用于基于 CE 的 HMIs 分析，它也具有在原子吸收光谱（AAS）、电感耦合等离子体质谱（ICP-MS）和离子色谱（IC）等方面的应用潜力。
