>>21560954
tl;dr the typical drug test most people get checks for the concentration of things that should normally be in the urine. Color/Clarity is commented on, but isn't a determining factor, the biochemical tests are.
In broad strokes, there's 3 kinds of urine drug tests that you'll do. You go to the ER, and they do a screen to make sure you aren't on any drugs that might interact with other medications. I'm a lab guy, not a MD, so I dunno the actual reasoning behind it, probably some degree on if and what pain meds they might prescribe. And that doesn't get any quality checks to try and figure out if it's a tampered with sample. Then there's the urine chain of custody draws, which is typically what you do for pre-employment or for cause, and it's the exact same testing methodology as the ER screen, but with all the CoC stuff, and they also run an SG and creatinine to check for potential false negatives due to dilution. Typically those samples are rejected and a recollect request is submitted in the report. The ordering location can request getting those pushed through for CG/MS if they wanna pay a bunch more money though. And that testing is the science magic that breaks everything down to the type and number of molecules in it, and there's really no cheating that. You might be able to adulterate it to break down the drug metabolite, but then the foreign substance would be detected as well.
