Micellar electrokinetic chromatography method for the determination of sulfamethoxazole, trimethoprim and their main metabolites in human serum

A complete analytical procedure, including sample clean-up and a micellar electrokinetic chromatographic method, is presented for the determination of sulfamethoxazole, trimethoprim, and their main metabolites by using 20 mmol L(-1) borate buffer (pH 9.3), 25 mmol L(-1) sodium dodecylsulfate, and 5% v/v acetonitrile as electrolyte. The separation was carried out at 30 kV and 20 degrees C in a fused silica capillary (60.2 cm x 75 microm inner diameter) fitted with a window in the capillary cartridge of 100 x 800 microm. The detector response was linear from the limit of quantification to 3 mg L(-1) for the individual components. The limits of quantification ranged from 0.13 up to 0.24 mg L(-1). The method was applied to human serum, previously spiked at different concentrations of all the analytes, and recoveries between 95% and 108% were obtained.