Ash content anti oxidant 168

Lately we have been asked about the test method of our anti oxidant 168, Omnistab AN 168, and why ASH is not among the specifications? Well, here's the answer; because there is some phosphonium content of AN 168, when testing ASH, it is easy to react with other substances such as silicon dioxide. So it's difficult to test the value of ASH. This is the reason why ASH does not value the quality of AN 168 as one of the standards.