Accurately weigh about 1 g of Sulisobenzone, and dissolve in 20 mL of water in a conical flask. Add 200 mL of dehydrated isopropyl alcohol, titrate a portion with 0.1 N
tetrabutylammonium hydroxide VS, and determine the two endpoints potentiometrically. Calculate the amount, in mg, of C14
S in the portion of Sulisobenzone taken by the formula:
in which 308.31 is the empirical weight of sulisobenzone; C
is the concentration, in moles per liter, of the 0.1 N tetrabutylammonium hydroxide VS; and V1
are the volumes, in mL, of titrant needed to reach the first and second endpoints, respectively.