期刊
ANALYTICA CHIMICA ACTA
卷 491, 期 2, 页码 173-179出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/S0003-2670(03)00806-7
关键词
capillary electrophoresis; large volume stacking; high pH; coated capillary
Large volume stacking using the electroosmotic flow (EOF) pump (LVSEP) in capillary electrophoresis under a reverse potential is a convenient and straightforward approach for on-line concentration of dilute anionic sample solutions. LVSEP achieves automatic sample matrix removal and subsequent separation without intermediate polarity switching nor complicated instrumental setup. Since anionic analytes should move against the EOF in LVSEP, EOF needs to be suppressed. We extended the range of LVSEP up to pH 11 using various EOF suppression methods, such as dynamic coating by polymer pretreatment and permanent coating. Weakly acidic organic compounds (pK(a) < 5.2), chlorinated phenols (pK(a) = 7-9), and aromatic amino acids (pK(a) similar to 9.3) were concentrated and separated. By hydrodynamically filling the whole capillary of 27 cm long with the sample solution, fast and reliable injection was achieved and sensitivity enhancement factors as large as 170 were readily obtained in less than 8 min. (C) 2003 Elsevier B.V. All rights reserved.
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