Determination of calcium in unused lubricating oil blends by direct small-scale complexometric titration

Abstract

A small-scale complexometric titration procedure has been developed for the direct determination of calcium in unused lubricating oils. The procedure utilises trans-1,2-diaminocyclohexane-NNN′N′-tetraacetic acid as titrant and di(2-hydroxyphenylimino)ethane, commonly known as glyoxalbis(2-hydroxyanil), as the specific indicator for calcium. The method is suitable for the determination of calcium in unused lubricating oil blends containing calcium, zinc and magnesium. The method cannot be applied to oils containing barium additives.