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Solid‐phase extraction and large‐volume sample stacking with an electroosmotic flow pump in capillary electrophoresis for determination of methotrexate and its metabolites in human plasma
Author(s) -
Kuo ChienYuan,
Chiou ShyhShin,
Wu ShouMei
Publication year - 2006
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.200500800
Subject(s) - capillary electrophoresis , chromatography , stacking , capillary action , extraction (chemistry) , solid phase extraction , chemistry , phase (matter) , human plasma , volume (thermodynamics) , analytical chemistry (journal) , materials science , physics , organic chemistry , quantum mechanics , composite material
This paper describes approaches for large‐volume sample stacking (LVSS) with an EOF pumpin CE for the determination of methotrexate (MTX) and its metabolites in human plasma. After pretreatment of plasma through a SPE cartridge, a large sample volume was loaded by hydrodynamic injection (3 psi, 70 s) into the capillary filled with phosphate buffer (70 mM, pH 6.0) containing 0.01% polyethylene oxide. Following removal of a large plug of sample matrix from the capillary using polarity switching (—25 kV), the separation of anionic analytes was subsequently performed without changing polarity again, achieving an improvement of sensitivity of around a 100‐fold. The method was applied to therapeutic drug monitoring of MTX in one acute lymphoblastic leukemia patient. This study is one of very few applications showing the feasibility of LVSS in analysis of biological samples by CE.