The determination in Problem 15-9 was modified to use the standard-additon method. In this case, a 4.236-g tablet was dissolved in sufficient 0.10 M HCI to give 1.000 L. Dilution of a 20.00-mL aliquot to 100 mL yielded a solution that gave a reading of 448 at 347.5 nm. A second 20.00-mL aliquot was mixed with 10.0 mL of 50-ppm quinine solution before dilution to 100 mL. The fluorescence intensity of this solution was 525. Calculate the percentage of quinine in the tablet.
Problem 15-9
Quinine in a 1.664-g antimalarial tablet was dissolved in sufficient 0.10 M HCI to give 500 mL of solution A 20.00-mL aliquot was then diluted to 100.0 mL with the acid. The fluorescence intensity for the diluted sample at 347.5 nm provided a reading of 245 on an arbitrary scale. A standard 100-ppm quinine solution registered 125 when measured under conditions identical to those for the diluted sample. Calculate the mass in milligrams of quinine in the tablet.