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CE‐ESI‐MS of biological anions in plastic capillaries at high pH
Author(s) -
Benavente Fernando,
SanzNebot Victoria,
Barbosa José,
van der Heijden Rob,
van der Greef Jan,
Hankemeier Thomas
Publication year - 2007
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.200600461
Subject(s) - electrolyte , peek , capillary action , analytical chemistry (journal) , chromatography , chemistry , materials science , hydrolysis , ammonia , composite material , polymer , electrode , organic chemistry
In this study, the potential of poly(methylmethacrylate) (PMMA, Plexiglas) and polyether ether ketone (PEEK) tubing for CE‐ESI‐MS separations of anions at high pH values was examined. A set of model compounds of biological interest was used to investigate the main operational parameters for CE‐ESI‐MS, such as the sheath‐flow interface design, the polarity of the ionization voltage, the use of ammonia‐based separation electrolytes, and the sheath liquid composition. Optimum separations and detection sensitivities in negative ESI mode were obtained using a running electrolyte of 75 mM of ammonia at pH 11 and a sheath liquid of 60:40 v/v or 75:25 v/v isopropanol/water with 0.5% v/v of ammonia. At these experimental conditions, PMMA and PEEK capillaries show good hydrolytic stabilities and lower EOF values than fused‐silica columns. Better separation resolutions were obtained with PMMA capillary, but this plastic rapidly swelled and bled because of its limited chemical resistance to the sheath liquid. PMMA columns equipped with a fused‐silica tip were used for a safer exposure to the sheath liquid, but the inner surface of the fused‐silica tips had limited stability at pH 11. On the other hand, good separations and reproducibility on migration times and peak areas were obtained using PEEK capillaries without capillary column deterioration.