Originally Posted by Burnt Toast
An initial assay screen is performed first, usually with a cutoff threshold of 50 ng. But a client (employer) can opt for an assay screen with a threshold as low as 20 ng.
Do you have a copy of your COC form (you should)? It would state the type of urine test being performed in the form of a test code.
A typical test code would read something like this:
SAP 5-50 w/NIT
...which translates into Substance Abuse Panel (screen), Five types of drugs to be screened, with a 50 ng cutoff threshold for THC. The 'NIT' code means that they will be performing a validity test which includes checking for excessive nitrites. However, validity checks had become lab SOP in recent years, making the indication of the 'NIT' code less and less necessary.