Selective focusing of catecholamines and weakly acidic compounds by capillary electrophoresis using a dynamic pH junction
Selective focusing of catecholamines and weakly acidic compounds by capillary electrophoresis using a dynamic pH junction
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DOI：
10.1021/ac990898e
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发表时间：
2000-03-15
影响因子：
7.4
通讯作者：
Chen, DDY
中科院分区：
文献类型：
--
作者：
Britz-McKibbin, P;Chen, DDY
采用毛细管电泳法对多段电解液体系中分析物的选择性聚焦进行了系统的研究。研究发现，样品和背景电解液区域之间的动态pH连接可用于聚焦两性离子儿茶酚胺和弱酸性化合物，而不需要使用特殊的两性阳离子。样品和背景电解液区域的pH值和络合剂浓度的差异被确定为通过改变毛细管两个不同部分的分析物的局部速度而引起聚焦。使用动态pH连接的分析物的速度差诱导聚焦(V-DIF)允许大量样品的进样，显著提高了CE的浓度灵敏度。在优化的条件下，用常规的紫外吸收法测定肾上腺素的检出限约为4×10~(-8)M(原始样品)。此外，通过将如此大的样品体积聚焦到狭窄的区域中，可以实现大于一百万个理论板的分离效率。多段电解液系统可导致动态pH连接的形成，可调整以提高特定分析物的浓度灵敏度，其化学性质已知。
A systematic study of selective analyte focusing in a multisection electrolyte system by capillary electrophoresis (CE) is presented. It was found that a dynamic pH junction between sample and background electrolyte zones can be used to focus zwitterionic catecholamines and weakly acidic compounds without the use of special ampholytes. Differences in pH and concentration of complexing agents, such as berate, in the sample and background electrolyte zones were determined to cause focusing through changes in the local velocity of the analyte in two different segments of the capillary. Velocity-differerence induced focusing (V-DIF) of analytes using a dynamic pH junction allowed the injection of large sample volumes and significantly improved the concentration sensitivity of CE. Under optimized conditions, the limit of detection for epinephrine was determined to be about 4 x 10(-8) M (the original sample) with conventional UV absorbance detection. Moreover, separation efficiencies greater than a million theoretical plates can be achieved by focusing such large sample volumes into narrow zones. Multisection electrolyte systems, which lead to the formation of a dynamic pH junction, can be tuned toward improving the concentration sensitivity of specific analytes their chemical properties are known.