Utility of quercetin for determination of some tertiary amine and quaternary ammonium salts

A simple and sensitive spectrophotometric method for the assay of eight drugs containing quaternary ammonium or tertiary amine moieties is described. The method is based on the interaction of these drugs with quercetin after its oxidation with N -bromosuccinimide (as counter ion) to give highly colored ion-pairing complexes extractable with organic solvents. The absorbances of the colored complexes are measured in the range of 528–560 nm. Beer's law is obeyed for the studied drugs in the range 5–30 μ g ml −1 . The method is successfully applied to the analysis of the studied drugs in commercial dosage forms.