You are using terms in a way that makes no sense.
A masking agent is a reagent used in chemical analysis which reacts with chemical species that may interfere in the analysis. In sports a masking agent is used to hide or prevent detection of a banned substance or illegal drug like anabolic steroids or stimulants. Diuretics are the simplest form of...
https://en.m.wikipedia.org/wiki/Masking_agent