Rapid simultaneous determination of alkylxanthines by CZE and its application in analysis of pharmaceuticals and food samples

Capillary electrophoresis (CE) offers the possibility of fast, cheap and reproducible separations for pharmaceutical preparations. Alkylxanthines make up a family of compounds that are used in the treatment and prevention of bronchi asthma and chronic pulmonary disease. The group of analysed compounds include caffeine, dyphylline, theophylline, theobromine and enprofylline. This paper shows a simple capillary zone electrophoretic (CZE) method for separation of this group of xanthines. Using 20 mM borate buffer at pH 9.4 as running buffer at 55 °C it was possible to complete a total separation of a sample in 2 min. Limits of detection in the range 1.9-2.5 mg l−1 were achieved with %R.S.D. of 0.06-0.22% (n = 5). The technique is applied to a range of samples containing the analytes, including tablets and chocolate. Reproducibility (%R.S.D.) of the chocolate analysis technique by CZE was less than 4.5%.