开管离子色谱柱的制备与表征

近年来,开管离子色谱(OTIC)的研究已取得重大进展,尤其是兼容OH^-淋洗液的OTIC柱的成功研制使OTIC梯度洗脱得以实现。该文介绍了各种OTIC柱的制备和表征方法,涵盖早期的二氧化硅开管柱和新近出现的有机聚合物基质开管柱,对静电乳胶附聚的OTIC柱的一系列表征方法进行了系统阐述,包括开管柱柱容量的实验测定和理论计算方法、固定相相同时填充柱与开管柱之间的联系、柱效改善方法以及开管柱均一性表征等。

Preparation and characterization of open tubular ion chromatographic columns

In recent years, significant progress has been made in the area of open tubular ion chromatography (OTIC). In particular, gradient OTIC has been realized through the development of hydroxide eluent-compatible OTIC columns. This review covers the preparation and characterization of different OTIC columns, ranging from the historic silica-based columns to the newly emerging polymer-based open tubular (OT) columns. The preparation of various OTIC stationary phases, from grafted to latex agglomerated and monolayer to multilayer phases, has been briefly introduced. The characterization of electrostatic latex agglomerated OTIC columns has been extensively discussed, e. g. fluorescent ion displacement chromatography, frontal displacement chromatography, and frontal reaction chromatography have been used to measure the capacities of OT columns, and the results are compared with the theoretical calculation values. The variable α_iex, defined as the number of ion-exchange equivalents per unit surface area, is used as an indicator of the capacity of OT columns, to enable a straightforward comparison between OT columns having different inner diameters (i.d.). The newly introduced column capacity parameter, γ_iex, defined as the stationary phase capacity per unit liquid volume present, is used to investigate the relationship between packed and OT columns when using the same stationary phase. Methods for improving the column efficiency, such as decreasing the column diameter and/or increasing the column temperature, are presented. In addition, determination of the functionalization uniformity along an OT column by (a) separately measuring the capacities of two halves of the column, (b) measuring the retention factors for several ions in successive 10 cm segments of the column in multiple injections, and (c) measuring the retention variance of a single ion in different segments of the column from a single injection, is discussed.