ASTM D6173-97(2005)

The most common anionic surfactants presented in this test method are used widely in synthetic detergents and other household cleaners. Current analysis of the active matter in these anionic surfactants involves the two-phase aqueous/chloroform titration with a mixed indicator, organic dyes such as disulphine blue/dimidium bromide (see Test Method D 3049), and methylene blue (see Test Method D 1681). This test method eliminates the use of hazardous chloroform, the use of which is restricted for environmental and toxicological reasons.

This test method also describes the titration of various ratio blends of sodium alkylbenzene sulfonate and sodium xylene sulfonate. Active matter content in these blends is attributable directly to sodium alkylbenzene sulfonate. Therefore, the presence of various amounts of sodium xylene sulfonate in these blends does not interfere with the determination of percent actives.

1.1 This test method is based on a potentiometric titration of common anionic surfactants and blends of anionic surfactant with a hydrotrope. This test method solely is intended for the analysis of active matter in the following surfactants: alcohol ether sulfate, alpha olefin sulfonate, alkylbenzene sulfonic acid, alcohol sulfate, sodium alkylbenzene sulfonate/sodium xylene sulfonate blend (5:1), sodium alkylbenzene sulfonate/sodium xylene sulfonate blend (16:1), and sodium alkylbenzene sulfonate/sodium xylene sulfonate blend (22:1). It has not been tested for surfactant formulations.

1.2 This standard does not purport to address all the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Material Safety Data Sheets are available for reagents and materials. Review them for hazards prior to usage.