Validated spectroscopic methods for the estimation of triamterene in bulk powder and capsule form via derivatization reactions.

Sensitive, simple and specific spectrophotometric and spectrofluorimetric methods were developed for the determination of triamterene in bulk powder and pharmaceutical dosage form. The spectrophotometric method (Method A) is based on the formation of an ion-pair complex with eosin Y in acetate buffered solution of pH 3.7 followed by measuring the absorbance at 545 nm. The absorbance-concentration plot is rectilinear over the range 3.0-15.0 μg/mL with a limit of detection (LOD) of 0.429 μg/mL and a limit of quantitation (LOQ) of 1.031 μg/mL. The spectrofluorimetric method (Method B) is based on the reaction of triamterene with 7- chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) in basic solution (pH 10) to form a product with high fluorescence measured at 546 nm after being excited at 438 nm. The plot of fluorescence versus concentration is linear within the range 2.0-10.0 μg/mL. The suggested methods were applied for the analysis of commercial capsules containing the studied drug with successful results. The results obtained from the proposed method were statistically compared with those of a reported one and revealed good agreement. The presented methods are useful in routine analysis of triamterene in laboratories of quality control.