I went through this with EcstastData. The Marquis, meeks and mandelin tests are not 100% for most of what is looked for on this site. I had a very nice and long discussion with a person at EctastyData about testing and the color changes and such of specifically oxy over the course of a week. If you do a search on oxycodone on their site and look at their test results and color samples, some will show no change, some will show slight change and some will show big changes just as mrpibbpenguin shows. When I asked about that specifically, he told me it has a lot to do with how the different fillers and binders will show up. I was really depressing for me, especially after spending the money I did on my 5 reagent kit I bought. I test everything I get and I only use the test now to try and make sure (or at least settle in my mind) that there is nothing really bad in what I bought. Even testing the different brands from the pharmacy will give me different colors (if any) for my script of the same med I have been scribed for years.
I just got some climbing gear and I swear its metho drones instead of climbing gear, but the test show no reactions at all. The only way to be 100% sure is GC/MS, so just be careful and remember these kits were made to test MDMA/ecstasy and the other things were added later.
