Three commercial products containing known amounts of
FEX were analyzed. Five tablets of each product were separately weighed, and then the tablets were powdered and mixed.
A portion of the powder known to contain an equivalent
amount of one tablet was accurately weighed and
sonicated with methanol for 30 min. It was then filtered into
a volumetric flask and completed to the mark with methanol
to make a stock solution. Working solutions of 50 ppm in
methanol were prepared. Appropriate aliquots from the working solution were taken for the determination of FEX in
samples.