Method to determine ibuprofen content in dosage forms
Common methods in quantitative analysis of ibuprofen are


titration with sodium hydroxide in methanol,
potentiometric titration,
chromatography combined with mass spectrometry,
IR spectroscopy[1], or
UV spectroscopy (273 $\pu{nm}$[1]).


Some of these methods, e.g. UV or IR spectroscopy require extraction of the active ingredient.

Ref.: [1] S. R. Matkovic, G. M. Valle and L. E. Briand, Quantitative analysis of ibuprofen in pharmaceutical formulations through FTIR spectroscopy