Rapid Simultaneous Determination of Three Methylxanthines in Human Plasma by Capillary Electrophoresis

Abstract

A simple capillary electrophoresis method is described for simultaneous determination of three methylxanthines, theophylline, dyphylline, and caffeine in human plasma. Plasma proteins are precipitated by acetonitrile and the supernatant was performed in Tris buffer (20 mM; pH 9) with sodium dodecyl sulfate (SDS) (150 mM) as an anionic surfactant. Several parameters affecting the separation of the drugs were studied, including the pH and concentrations of the Tris buffer and SDS. Application of the proposed method to the determination of theophylline and dyphylline in human plasma proved to be feasible. The practicability of the proposed method is demonstrated on a healthy volunteer.

Keywords:

• Capillary electrophoresis
• Human plasma
• Methylxanthines
• CZE
• Validation
• MEKC‐CE

Acknowledgment

The authors are grateful to the National Science Council, R.O.C., for financial support of the work (NSC 90‐2745‐p‐037‐001).