Johns Cameron, Macka Miroslav, Haddad Paul R
Australian Centre for Research on Separation Science, School of Chemistry, University of Tasmania, Private bag 75, Hobart, Tasmania 7001, Australia.
J Chromatogr A. 2003 May 16;997(1-2):87-94. doi: 10.1016/s0021-9673(03)00062-1.
The cationic dye, chrysoidine, has been used for the first time as a probe for the indirect photometric detection of cations. The dye has been used as a probe at concentrations of 5 mM, which is roughly an order of magnitude higher than for other cationic dyes used previously for the same purpose, in order to minimise electromigrational dispersion. Baseline instability was minimised by a combination of coating the capillary with poly(ethyleneimine), addition of a neutral polymer to the electrolyte, and the application of a small amount (20 mbar) of hydrodynamic pressure during the separation. Separation of a mixture containing alkali metals, alkaline earths, transition metals and lanthanides was achieved by the addition of 2-hydroxyisobutyric and lactic acid as complexing agents. Excellent peak shapes were observed over a wide range of analyte mobilities due to the moderate mobility of the probe. The high absorptivity (26733 l mol(-1) cm(-1)) provided by chrysoidine in comparison with typically used, less absorbing probes, was reflected in limits of detection which were typically less than 0.5 microM. These are amongst the lowest reported using hydrodynamic injection without the use of large volume stacking methods. The use of 2-hydroxyisobutyric and lactic acids as complexing agents at pH values close to their pKa values provided suitable buffering which was highlighted by very good reproducibility of migration time, corrected peak area and peak height.
阳离子染料碱性菊橙首次被用作间接光度法检测阳离子的探针。该染料以5 mM的浓度用作探针，这比之前用于相同目的的其他阳离子染料的浓度大致高一个数量级，以便将电迁移分散降至最低。通过用聚乙烯亚胺涂覆毛细管、向电解质中添加中性聚合物以及在分离过程中施加少量（20毫巴）的流体动力学压力，基线不稳定性降至最低。通过添加2-羟基异丁酸和乳酸作为络合剂，实现了含有碱金属、碱土金属、过渡金属和镧系元素的混合物的分离。由于探针的迁移率适中，在很宽的分析物迁移率范围内观察到了出色的峰形。与通常使用的吸收性较低的探针相比，碱性菊橙具有较高的吸光度（26733 l mol(-1) cm(-1)），这反映在检测限通常小于0.5 microM。这些是在不使用大体积堆积方法的情况下，使用流体动力学进样所报道的最低检测限之一。在接近其pKa值的pH值下使用2-羟基异丁酸和乳酸作为络合剂提供了合适的缓冲，迁移时间、校正峰面积和峰高的非常好的重现性突出了这一点。
