ASSESSMENT OF THE SUBSTANTIVITY OF CATIONIC QUATERNARY COMPOUNDS TO HAIR BY POTENTIOMETRIC TITRATION USING THE SURFACTANT ELECTRODE

A new method to measure the sorption of cationic quaternary compounds by hair is reported. The method employs the potentiometric titration of cationic compounds, using a surfactant electrode as an endpoint indicator. Cationic uptake was determined from the difference of the cationic content in the solutions before and after the treatment of hair. By this method, the substantivity to bleached hair of mono- and polyfunctional quaternary ammonium conditioning agents, as well as animal and botanical quaternary ammonium proteins, was measured as laurdimonium hydrolyzed wheat protein > quaternium-26 > stearalkonium chloride > cocodimonium hydrolyzed keratin protein. The results are consistent with previously published accounts: cationic uptake of quaternary compounds increases with increased solution concentration, treatment time, temperature, and hair damage.