Boyce M C, Breadmore M, Macka M, Doble P, Haddad P R
Edith Cowan University, Perth, Western Australia, Australia.
Electrophoresis. 2000 Sep;21(15):3073-80. doi: 10.1002/1522-2683(20000901)21:15<3073::AID-ELPS3073>3.0.CO;2-H.
The application of indirect spectrophotometric detection was investigated for a capillary electrochromatographic system in which an anion-exchange stationary phase (in the form of aminated latex particles) was coated onto the wall of a fused-silica capillary. The study has focused on the choice of the type and concentration of the absorbing coion (probe) added to the background electrolyte and the role of this species in manipulating the ion-exchange contributions to the separation with a view to controlling the selectivity of the separation. Common inorganic anions were used as analytes and nitrate, p-toluenesulfonate, nicotinate, and chromate were investigated as probes. It was found that most of these probes produced only a limited range of separation selectivities when their concentration was varied over the practically accessible range. p-Toluenesulfonate provided the greatest variation in selectivity, but peak distortion due to electromigration dispersion was evident for the faster ions. When variation of the separation selectivity - from predominantly electrophoretic in nature to predominantly ion-exchange in nature - was desired, this was best achieved by varying the type of probe rather than its concentration. For example, the nitrate probe provided predominantly electrophoretic separations with good peak shapes and high efficiencies. A comprehensive list of probes, ranked in order of ion-exchange selectivity coefficients determined by ion chromatography, was compiled and this proved to be a useful tool to assist in the selection of a probe for a desired separation selectivity. The limits of detection for the analytes and probes studied ranged from 20-55 micromol for the chromate system to 230-600 micromol for the nicotinate system, with nitrate and p-toluenesulfonate giving intermediate values.
研究了间接分光光度检测在毛细管电色谱系统中的应用，该系统中阴离子交换固定相（胺化乳胶颗粒形式）涂覆在熔融石英毛细管内壁上。该研究聚焦于添加到背景电解质中的吸收性共离子（探针）的类型和浓度的选择，以及该物质在操纵离子交换对分离的贡献方面的作用，以期控制分离的选择性。使用常见无机阴离子作为分析物，并研究了硝酸盐、对甲苯磺酸盐、烟酸盐和铬酸盐作为探针。结果发现，当这些探针的浓度在实际可及范围内变化时，大多数探针仅产生有限范围的分离选择性。对甲苯磺酸盐提供了最大的选择性变化，但对于较快的离子，由于电迁移分散导致的峰变形很明显。当希望分离选择性从主要是电泳性质变为主要是离子交换性质时，最好通过改变探针的类型而不是其浓度来实现。例如，硝酸盐探针提供主要为电泳分离且峰形良好、效率高。编制了一份按离子色谱法测定的离子交换选择性系数排序的探针综合列表，事实证明这是一种有助于选择具有所需分离选择性的探针的有用工具。所研究的分析物和探针的检测限范围从铬酸盐系统的20 - 55微摩尔到烟酸盐系统的230 - 600微摩尔，硝酸盐和对甲苯磺酸盐给出中间值。
