Failed initial 50ng/ml screen but PASSED 15ng/ml lab test?

[marcosnell42]

Hey all, getting ready to pass a drug test so I quit smoking on 3-25. I wanted to make sure I'd pass so I went to a lab to test myself on 4-12 (18 days). Former bowl a day smoker of dank bud, 190lbs, 6', average metabolism, male, ride my bike 2 miles a day.

I took a 5-panel test and to my great surprise I failed the initial screen at 50 ng/ml. They sent it to the lab for additional GC/MS confirmation at 15ng/ml, and I called back the next day and they showed that I PASSED.

How is this possible? I thought the lab test was stricter, hence the lower cut off. Does this mean the initial test was a false positive? Or worse, could the lab test have been faulty? I just want to make sure I'll pass my test, it'll probably come around 4-23.

marcosnell42 Reviewed by marcosnell42 on 04-19-2010. Failed initial 50ng/ml screen but PASSED 15ng/ml lab test? Hey all, getting ready to pass a drug test so I quit smoking on 3-25. I wanted to make sure I'd pass so I went to a lab to test myself on 4-12 (18 days). Former bowl a day smoker of dank bud, 190lbs, 6', average metabolism, male, ride my bike 2 miles a day. I took a 5-panel test and to my great surprise I failed the initial screen at 50 ng/ml. They sent it to the lab for additional GC/MS confirmation at 15ng/ml, and I called back the next day and they showed that I PASSED. How is this Rating: 5

[Burnt Toast]

What likely happened was an inexperienced tech who've misinterpreted a faint line on the Immunoassay as a "fail" and sent it off to the GC/MS. When that happens, the sample would come back as a negative. A faint line still counts as a line, which translates a negative - sample being below the 50ng threshold.

Its a common misconception that the GC/MS is a more "stricter" , or "sensitive" test than the I/A. Its not so. The GC/MS is just more accurate. In actuality, a 50ng I/A screen is equivalent to the 15ng GC/MS. Their cutoff thresholds are numerically different because the I/A screen recognizes the composition of all 31 THC metabolite concentrations, while the GC/MS recognizes only one, which is the most prevalent metabolite concentration (THC-COOH).
To test negative on the I/A, the whole composite of the 31 metab concentrations must register below 50ng.
To test negative on the GC/MS, only that one metabolite concentration must register below 15ng

[marcosnell42]

That makes sense. To be honest, she showed me my test, and there was one dark line, and one extremely (extremely) faint line. I'd taken a home test and got a faint line but this was even fainter, one shade above invisible. So I guess I should chill out.

[loveblunts]

That makes sense. To be honest, she showed me my test, and there was one dark line, and one extremely (extremely) faint line. I'd taken a home test and got a faint line but this was even fainter, one shade above invisible. So I guess I should chill out.

i keep getting the same result and i dont really kno if im passing or not.
line is very very faint.. can be seen better when kind of under light... so i dont kno if im passing these home tests or not... so i keep telling myself that i am failing. so im confused too