A novel technique for on-capillary preconcentration of anionic compounds applied to the trace analysis of rapamycin in human blood by capillary electrophoresis.
Electrophoresis
; 26(1): 161-5, 2005 Jan.
Article
en En
| MEDLINE
| ID: mdl-15624180
ABSTRACT
A capillary electrophoretic (CE) method with UV detection at 278 nm has been developed for analysis of the immunosuppressant rapamycin (sirolimus) in human blood at low microg.L(-1) levels. Separation has been achieved in an acidic carrier electrolyte containing sodium dodecyl sulfate and 20% v/v methanol. For sample cleanup and preconcentration, both an off-line solid-phase extraction step using a silica-based reversed-phase material and a newly developed on-capillary focusing technique have been employed. The subsequent treatment of rapamycin under alkaline conditions leads to a cleavage of the lacton bond of the molecule, generating a negatively charged carboxylic group which allows electrokinetic injection into the CE instrument. During the injection process, the negatively charged analyte migrates into an acidic carrier electrolyte, so that it becomes neutral due to protonation and is focused at the capillary inlet. Injection times of 300 s at -7.5 kV could be applied without band-broadening. Results for real samples indicated that the method is fully suited for routine applications and may be an attractive alternative to established liquid chromatographic techniques.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Electroforesis Capilar
/
Sirolimus
Tipo de estudio:
Evaluation_studies
Límite:
Humans
Idioma:
En
Revista:
Electrophoresis
Año:
2005
Tipo del documento:
Article
País de afiliación:
Austria