most commonly urinalysis drug test is done by a immunoassay based screening. (strips) And if those read positive, then the sample is sent away for GC-MS/LC-MS to rule out false-positives. Most companies will not go out of their way to run GC-MS/LC-MS on the samples because it is expensive. I would bet most companies would rely on just immunoassay alone if they were allowed to.
The immunoassay works by testing against antibodies.
So with the drug testing strip, you are not detecting the drug metabolites themselves, but you are detecting the immune response with the drug metabolite 'antigens'.
This is more accurate than a reagent based test, but will still trigger a positive for anything with a similar structure/activity relationship. If it is metabolized in the same way, it will trigger the same antibody.
So any amphetamine would test positive for amphetamine, including psychedelic amphetamines. Immunoassays can be pretty structure specific as well, differentiating between amphetamines like MDxx and N-methyl amphetamines. Even so far as differentiating enantiomers.
The selectivity is a matter of sensitivity, not exclusivity. So if you have an antibody that is selective for d-amphetamine, it can detect d-amphetamine at 0.1ng/mL, and can detect false positives like ephedrine at 20ng/mL, and then false positives of phenethylamines at 100ng/mL, etc.
so in this example the natural phenethylamines in your blood won't register as a false positive as long as they are below 100ng/mL.
So I would lean towards no, phenethylamines like mescaline should not cause a false positive on an immunoassay. As long as you aren't dosed up on a gram of mescaline while you taking the pee test. However, since dosage for mescaline IS much higher relatively speaking, the chances of getting a false positive is higher for a phenethylamine like mescaline, vs a phenethylamine like 2c-b.
It is also possible psychedelic phenethylamines are more sensitive to a false positive to the MDMA antibody, since they are both oxygenated phenethylamines, vs the unsubstituted amphetamine.
In my experience however, I've taken one of these immunoassay tests after taking TMA-2, an oxygenated psychedelic amphetamine, and it tested a false positive for amphetamine and not MDMA. Results vary on the specific amphetamine antibody being used, and there is not always an obvious trend of sensitivities towards the substituted analogs, these have been well studied in the literature.
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