APPLICATION OF COLUMN-SWITCHING TECHNIQUES TO THE DETERMINATION OF MEDIUM POLARITY DRUGS - DETERMINATION OF ACETAZOLAMIDE IN URINE

A column-switching system for the determination of the medium polarity diuretic acetazolamide in urine, has been designed. An Hypersil ODS C 18, 30 mum (20 x 2.1 mm I.D.) pre-column was used for the pre-concentr ation and separation of acetazolamide from the biological matrix. The most polar urinary compounds were removed by washing the pre-column wi th a phosphate buffer solution (pH 3), and the fraction of eluate cont aining the analyte was switched to a LiChrospher RP C18, 5 mum (125 x 4 mm I.D.) analytical column, where it was chromatographed using gradi ent elution with acetonitrile-water, and detected at 275 nm. The most apolar urinary compounds were directly discarded by means of a second switching valve. Under these conditions the recovery of drug was 96 +/ - 5% in the 0.50-100.0 mug/ml concentration range. The limit of detect ion was 10 ng/ml, the total analysis time being less than 8 min.