Somebody is making a lot of money selling those test strips. (Chertoff, perhaps?)
DINGDINGDINGDING!!! We have a WINNAH!
Gotta be honest - the way I see it, when someone approaches me and asks to sample my purchased-inside-the-secure-area beverage in whatever manner, I intend to guzzle the entire thing as fast as I can, toss 'em the empty, and walk the frak away. They can deal with THEIR trash, at that point, and I'll say it to their faces before walking away from them. Might ask them if they failed to screen the people who brought the pallets of food and drink - and the items themselves, for that matter - through "security" for delivery in the "secure area" the first time 'round, since they're wasting time pretending to check it again at the gate, as well.
If they're going to be morons, I'm going to make that blindingly and publically obvious to them.
Note -those test strips they use can't distinguish between hydrogen peroxide of a concentration useful in the production of explosives (something like 30+%, IIRC) and the concentration of H2O2 in Clear Care brand contact solution (~3%). So while contact solution is medically necessary and can be brought through "security" (even in >3oz bottles, although the screeners will argue with you), Clear Care will alarm their "security" analyzers and will be confiscated - or, rather, according to them, you'll "voluntarily surrender it" if you want to catch your flight.
So watch out for that, lens wearers. Of course, the glycerin in a lot of hand lotions alarms their analyzers, as well...