DETERMINATION OF SALICYLAMIDE IN PHARMACEUTICAL TABLETS BY HIGH-PERFORMANCE THIN-LAYER CHROMATOGRAPHY WITH ULTRAVIOLET ABSORPTION DENSITOMETRY

SUMMARY A new quantitative method using silica gel high-performance thinlayer chromatography (HPTLC) plates with fluorescent indicator, channels, and a concentration zone; instrumental bandwise application of standards and samples; development with dichloromethane–acetone, 4:1, as mobile phase; and ultraviolet absorption densitometry of fluorescence quenched zones is reported for determination of salicylamide in pharmaceutical formulations. The products analyzed to test the applicability of the method were diuretic tablets containing salicylamide, potassium salicylate, and caffeine as active ingredients in unspecified amounts, and extra-strength pain-relief tablets containing salicylamide (152 mg), acetaminophen (110 mg), aspirin (162 mg), and caffeine (32.4 mg). Precision, accuracy, linearity, limits of detection and quantitation, and selectivity were validated. Amounts of salicylamide ranged from 2.67 to 2.89 mg in the five diuretic tablets analyzed, and recoveries from five pain-relief tablets ranged from 104.7 to 107.1%. Within-day precision was 0.743% and 0.863% (n = 6) for analysis of the fifth diuretic and fifth pain-relief tablets, respectively. The interday precision was 1.35% and 1.33% (n = 5) for analysis of the fourth diuretic and fourth pain-relief tablets, respectively. Validation of the accuracy of the diuretic tablet results showed the error to be 1.10% for spiked blank analysis, and standard addition analyses gave errors of 1.75% and 0.40% for diuretic and pain-relief tablets, respectively, compared with fortification levels. The limits of detection and quantification were both 2.00 µg, and the correlation coefficient for the salicylamide calibration plot was 0.997 over the range 2.00 to 8.00 µg. The method is suitable for routine quality-control analysis of pharmaceuticals containing salicylamide.