What you can do is test the QF bottle with a validity test strip to make sure the Creatinine, specific gravity, pH, etc; are all within acceptable ranges. These test kits are inexpensive and can be found online by doing a Google search for drug adulteration test kits.

For a "how to" on using the test strip on the QF, read post #13 of this thread:
http://boards.cannabis.com/drug-test...ml#post1756820