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On‐column detection of multiphoton‐excited fluorescence in CE using hyphenated cylindrical‐square capillaries
Author(s) -
Xu Youzhi,
Chen Sheng,
Feng Xiaojun,
Du Wei,
Luo Qingming,
Liu BiFeng
Publication year - 2008
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200700238
Subject(s) - detection limit , capillary action , analytical chemistry (journal) , detector , excited state , fluorescence , chemistry , chromatography , range (aeronautics) , materials science , optics , atomic physics , physics , composite material
Multiphoton‐excited fluorescence (MPEF) is a complementary and useful mode of LIF detection in CE with advantages of ultra‐low mass detectability and spectral excitability, but it is currently quite limited by its end‐column configuration. In this article, we demonstrate a novel strategy of on‐column schemes that can greatly facilitate MPEF detection in CE. FITC‐labeled amine species were used as the model samples for the evaluation and comparison of those detection scenarios. By using the square capillary instead of the conventional cylindrical one, the on‐column MPEF could be readily achieved, with detection sensitivity of 0.72 μM that was comparable with the end‐column mode. However, this strategy unfavorably reduced separation efficiency. The theoretical plate number on averaging all the sample peaks was significantly decreased from 283 000 to 19 000/m. To minimize such an influence, a short square capillary acting as an on‐column MPEF detection cell was then mounted to a long cylindrical capillary responsible for the CE separation. Results indicated that both high separation efficiency (240 000/m) and better detectability (0.42 μM) were realized simultaneously by using this binary‐capillary configuration. Quantitative analysis was performed under the optimized detector configuration and revealed a linear dynamic range of 2 orders of magnitude, with mass detection limit down to the mid‐yottomole level.