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An ionic liquid coating for determination of sildenafil and UK‐103,320 in human serum by capillary zone electrophoresis‐ion trap mass spectrometry
Author(s) -
Qin Weidong,
Li Sam F. Y.
Publication year - 2002
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.200290028
Subject(s) - capillary electrophoresis , chromatography , chemistry , analytical chemistry (journal) , detection limit , capillary action , analyte , mass spectrometry , materials science , composite material
Ionic liquid (IL) was covalently bonded onto the silica capillary surface and the electroosmotic flow was reversed over a pH range of 3.5 to 7. Sildenafil (SL) and its metabolite UK‐103,320 (UK) in human serum were detected by solid‐phase extraction followed by capillary zone electrophoresis‐mass spectrometry analysis. The running buffer contained 10 m M acetic acid adjusted to pH 4.5 with 1 M ammonia, and the separating voltage was set to —25 kV. The adsorption of the analytes onto the bare capillary wall was eliminated by the IL coating and the drugs were baseline‐separated within 14 min with detection limits (S/N = 3) of 14 and 17 ng/mL for SL and UK, respectively. The method developed showed good intraday precision in terms of relative standard deviation (RSD) with respect to migration time (RSD ≤ 0.76%, n = 5) and peak area (RSD ≤ 3.4%, n = 5); the relative coefficients of linear regression for both targets were better than 0.99 within linear dynamic range (SL: 50–600 ng/mL; UK: 40–400 ng/mL). Satisfactory interday precision was obtained with respect to the slope of the regression (RSD ≤ 4.21%, n = 9) and the migration time (RSD ≤ 1.1%, n = 9). The IL coating could be used with stable electroosmotic flow (RSD = 2.78%, n = 10) for at least 80 h.