Simple and Rapid Determination of Denaturants in Alcohol Formulations by Hydrophilic Interaction Chromatography

Abstract

A hydrophilic interaction chromatography (HILIC) technique has been developed and validated for determination of common denaturants (denatonium benzoate, crystal violet and methylene blue) in denaturated alcohol formulations. Among the three different polar stationary phases (i.e., aminopropyl, cyanoethyl and silica) studied the cyanoethyl phase provided much stronger retention for the organic cations. It was shown that high efficiencies were reached only with anionic ion-pairing reagent that reduces the interactions with the silanol groups. The anion ion-pairing strength under HILIC conditions was: acetate < formate < trifluoroacetate < perchlorate. This study also investigated the effect of various experimental factors on the retention of the cyanoethyl stationary phase, such as acetonitrile content, pH and ion-pairing anion concentration in the mobile phase. The separation of three denaturants was achieved in about 8 min with a mobile phase containing 60% (v/v) acetonitrile and 10 mmol L⁻¹ HClO4. The proposed method was validated and applied to the determination of danaturating agents in various Lithuanian denaturated alcohol formulations.