A Rapid Method of Testing for Quaternary Ammonium Compounds in Milk

Abstract

A method has been developed for determination of QAC in milk. It is based on extraction and precipitation of QAC in a tetrachloroethane-acetone-eosin indicator solution. Interfering factors in the solvent-indicator fraction are removed by successive washings with distilled water and QAC then is titrated with a standard solution of anionic surface active agent. The first two steps of the procedure may serve as a presumptive or qualitative test for detection of QAC in milk. The subsequent steps are necessary for a determination of quantity of QAC present. The method has proven suitable for determining concentration in milk of QAC preparations commonly employed in dairy sanitation procedures. With suitable standards for comparison the method will determine quantities of QAC in the range of 5 to 100 ppm. in milk. © 1951, American Dairy Science Association. All rights reserved.