CHROMATOGRAPHIC MONITORING OF DIURETICS IN URINE SAMPLES USING A SODIUM DODECYL-SULFATE PROPANOL MICELLAR ELUENT

The effect of a varying pH, in the range 3-7, on the retention of seve ral diuretics eluted with a sodium dodecyl sulphate (SDS) micellar mob ile phase and with W detection was studied. Significant changes in the capacity factors (k') of the diuretics bumetanide, ethacrynic acid, f urosemide, probenecid and xipamide were observed. The protonation cons tants of these compounds were calculated from the k'-pH data. A study was also performed to select the optimum composition of the mobile pha se (pH, concentration of SDS and nature and concentration of alcohol) for the separation of the above diuretics and the diuretics amiloride, bendroflumethiazide, chlorthalidone, hydrochlorothiazide, spironolact one and triamterene. Maximum resolution was achieved with a 0.042 M SD S + 4.0% propanol eluent. Limits of detection (at 254 nm) ranged betwe en 0.082 mu g ml(-1) for xipamide and 0.76 mu g ml(-1) for ethacrynic acid. The method was applied to the study of the urinary excretion of several diuretics.