Designed for use with U.S. EPA Method 535, AccuStandard´s full set of standards is available to laboratories for method development and quality control. This includes standards for all 12 compounds plus the internal standard and the surrogate standard, for a total of 14 compounds in the set. U.S. EPA Method 535 is designed for the determination of six acetamide herbicides in the form of both ethanesulfonic acid (ESA) derivatives and oxanilic acid (OA) degradates in drinking water. The method uses LC-MS-MS for both identification and quantitation.