Most home tests carry the same cutoff limit as the DOT test (50 ng for the initial screening).

Even though their cutoffs numerically differ, a 50 ng assay screen is functionally equivalent to the 15 ng GC/MS. To find out how and why, hit the Forum Search button, using the terms "functionally equivalent metabolites".

A faint line is still a negative. Even if an untrained tech were to misinterpret a faint line as a "non-negative", and sent the sample off for confirmation, the sample would still come back as a negative.