Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748 05508-000 São Paulo, SP, Brazil.
Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748 05508-000 São Paulo, SP, Brazil.
Talanta. 2018 Feb 1;178:1040-1045. doi: 10.1016/j.talanta.2017.08.088. Epub 2017 Sep 1.
Methods for determination of glycerol and its electrooxidation products (neutral diols and carboxylates) by capillary electrophoresis (CE) with dual capacitively coupled contactless conductivity detectors (CD) are presented. Glycerol, dihydroxyacetone and glyceraldehyde were detected as anionic borate complexes in less than 3min under counter Electroosmotic Flow (EOF) mode (resolution of the critical pair of 1.8). Limits of detection (LODs) of 15, 15 and 10µmolL were obtained for glycerol, dihydroxyacetone and glyceraldehyde, respectively. Two methods of separation were used for the separation of carboxylates. The first one used the same Back Ground Electrolyte (BGE) containing borate, and the second used a BGE (pH 6.1) composed by 2-(N-morpholino)ethanesulfonic acid (MES), L-Histidine and a flow modifier. Better separation and LODs for carboxylates were obtained using Mes/Histidine as BGE. However, along with the non-applicability of this BGE to the determination of neutral diols, observation of the CD signals at two different points of the capillary (10 and 50cm apart from the injection tip) revealed interaction of the flow modifier with some species (mesoxalate and glyoxylate). The electrooxidation of a glycerol sample in alkaline media on an 8cm gold working electrode was evaluated by the developed methods. After 16h of electrolysis, 87% of the glycerol had been oxidized and formate, glycolate, hydroxypyruvate and glycerate were detected as the main products.
介绍了用双电容耦合非接触电导检测器（CD）的毛细管电泳（CE）测定甘油及其电氧化产物（中性二醇和羧酸盐）的方法。在反电渗流（EOF）模式下，甘油、二羟丙酮和甘油醛作为硼酸盐阴离子配合物在不到 3 分钟内被检测到（1.8 个关键对的分辨率）。甘油、二羟丙酮和甘油醛的检测限（LOD）分别为 15、15 和 10µmolL。为了分离羧酸盐，使用了两种分离方法。第一种方法使用了含有硼酸的相同背景电解质（BGE），第二种方法使用了由 2-（N-吗啉基）乙磺酸（MES）、L-组氨酸和流动改性剂组成的 BGE（pH 6.1）。使用 Mes/Histidine 作为 BGE 可以获得更好的分离和更低的 LODs 用于羧酸盐。然而，由于这种 BGE 不适用于中性二醇的测定，观察毛细管中两个不同点（距进样端 10 和 50cm 处）的 CD 信号，发现流动改性剂与某些物质（乙二醛酸和乙醛酸）相互作用。通过开发的方法评估了在碱性介质中 8cm 金工作电极上电氧化甘油样品的情况。在 16 小时的电解后，87%的甘油被氧化，检测到的主要产物有甲酸盐、乙二醇酸盐、羟丙酮酸和甘油酸盐。
