Acetylsalicylic acid contains not less than 99.5 per cent
and not more than the equivalent of
101.0 per cent of 2-(acetyloxy)benzoic acid, calculated with reference to the dried substance.
ASSAY
In a flask with a ground-glass stopper, dissolve 1.000 g in
10 ml of alcohol R. Add 50.0 ml of 0.5 M
sodium hydroxide. Close the flask and allow to stand for 1 h. Using 0.2 ml of phenolphthalein solution R as
indicator, titrate with 0.5 M hydrochloric acid. Carry out a blank titration.
1 ml of 0.5 M sodium
hydroxide is equivalent to 45.04 mg of C9H8O4.
Calculation:
Result:
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