Throughout, in the sense of:
From beginning to end of (an event or period of time):
would seem to apply, but I wouldn't use it. The problem with a one word solution like that (and particularly that one, which is the only one that comes to my mind at the moment) is that it would lead to ambiguity. Is it the sample that has corrupted "throughout", or does "throughout" refer to the period that the sample existed?
To improve the succinctness without losing meaning or introducing ambiguity, I'd simply drop the "of time" expression. After all, in this context could "that period" be anything other than a period of time?