There is no "zero-tolerance" test because every drug testing device has a cutoff threshold and if your urine sample registers below that cutoff threshold, its reported as a negative. Plain, sweet, and simple.

If youre worried about the GC/MS because of its 15 ng cutoff threshold, dont be.
Even though the cutoff thresholds are numerically different, a 50 ng assay screen is functionally equivalent to the 15 ng GC/MS. Their cutoff thresholds are numerically different because the 50 ng assay recognizes the composite of all 31 metabolite concentrations, while the GC/MS recognizes only 1 metabolite concentration. The threshold is set to a numerically lower number because that makes the two types of tests functionally equivalent.

As you may know, THC enters the body in its ingested form and exits the body as 31 different metabolite concentrations. The most prevalent form of those metabolite concentrations being THC-COOH. In order to test negative on the assay screen, the whole composition of the 31 metabolite concentrations must register below 50 ng/ml.

The GC/MS cutoff is at 15 ng because the machine only recognizes one metabolite concentration: the THC-COOH metabolite concentration. In order to test negative, that one metabolite concentration must register below 15 ng/ml.
Burnt Toast Reviewed by Burnt Toast on . Questions about Labcorp and home testing info I suppose I should start off with my basic info. I'm fairly tall (6') and weigh approximately 135lbs. I'm not very active (I don't work out but do go hiking or kayaking about once a month) and have been a habitual smoker (4-8 times daily) for at least the past 15 years or so. I typically prefer "b's" as I like a nice buzz but prefer not to be overly high. I do not like to lose control or act messed up. I have been a manager at a marketing company for the past 6 years... I started when the Rating: 5