Hello, I am doing the USP assay for arsanilic acid over again and getting results out of specification. Has anyone done this test? How about on a non-USP grade arsanilic acid? I end up having to transfer the test solution from a 125-mL Erlenmeyer into a 250-mL Erlenmeyer to finish and am getting way too much 0.1 N potassium permanganate added. This is occurring over a number of samples.