Chromatographic determination of diuretics in urine samples using hybrid micellar mobile phases with fluorimetric detection Original Research Article

A rapid and simple chromatographic procedure, that uses hybrid micellar mobile phases of sodium dodecyl sulphate (SDS), propanol and phosphate buffer at pH 3, and fluorimetric detection (λexc=270 nm, λem=430 nm), is reported for the determination of mixtures of seven diuretics of diverse efficacy (amiloride, bendroflumethiazide, bumetanide, furosemide, hydroflumethiazide, piretanide and triamterene), in urine samples. The application of a sequential optimization procedure for the resolution of the mixtures of the diuretics was problematic. However, their separation was achieved through the use of an interpretive optimization procedure based on the accurate description of the retention. The optimum mobile phase contained 0.055 M SDS-8% propanol. The limits of detection (ng/ml) and inter-day reproducibilities (%) in the urine samples were: amiloride (9.7, 5.7), bendroflumethiazide (10, 8.8), bumetanide (1.4, 3.6), hydroflumethiazide (7.1, 5.6), piretanide (54, 4.1), and triamterene (1.7, 1.4). Detection of urinary excretion of the diuretics was possible at least up to 24–72 h after their ingestion. Injection of furosemide standards originated four chromatographic peaks, which corresponded to the drug and diverse impurities.