Determination of triamterene in pharmaceutical formulations and of triamterene and its main metabolite hydroxytriamterene sulfate in urine using solid-phase and aqueous solution luminescence

Solid-phase extraction (SPE) (reversed-phase and mixed-mode) and nylon membranes were investigated as solid matrices for obtaining fluorescence signals from adsorbed triamterene (TA). Although a significant emission was found in all investigated surfaces, solid-phase extraction systems yielded the best results. The analytical figures of merit obtained under the best experimental conditions, using nonpolar/strong cation mixed phase MP1 discs and 5 ml of extracting sample, were: linear calibration range from 1.7 to 21 ng ml−1 (the lowest value corresponds to the quantitation limit), relative standard deviation, 1.3% (n = 5) at a level of 12.7 ng ml−1, and limit of detection, 0.6 ng ml−1 (calculated according to Clayton's definition, taking into account false positive and false negative errors). An approach for the spectrofluorimetric determination of triamterene in pharmaceutical formulations was successfully applied. In addition, a simple and rapid method for the separation and fluorimetric determination of triamterene and its main metabolite (hydroxytriamterene sulfate) in urine was developed and rendered very satisfactory results, requiring in this case the use of reversed-phase C18 solid-phase extraction.