Quote Originally Posted by jwalt9
I've been seeing posts here of people saying they have an upcoming 5-50 GC/MS Pre-Employment test coming up, and stuff like that... GC/MS testing is the most accurate UA (from what I've been reading), and I was under the impression that 99% of the time they do the simple lab test first, then any non-negative result gets sent to GC/MS testing.

So with people saying they have the upcoming GC/MS pre-employment UA test, does this just mean it will go to GC/MS if positive, or it will be that for the first step? If the employer tells me the same, 5-50 or 10-50 GC/MS test, will it just be the simple test to start with? Hope this is clear what I'm asking..
Yes it is clear what you are asking and you are almost right. All drug tests go through immunoassay first, then any "non-negative" results go to GC/MS. The immunoassay will usually use a cutoff of 50 ng/ml while GC/MS uses a cutoff of 15 ng/ml. Immunoassay test for 31 metabolites while GC/MS tests only for 1 metabolite, THC-COOH so even though the number are 50 and 15, they really correspond to about the same level of THC metabolites in the urine. Immunoassay on lab tests are usually conducted by lab testing equipment. Home tests or instant tests use immunoassay technology similar. You asked about that in the first of the two posts. Once in a while an employer can opt for the urine to get a dipstick test then those "non-negatives" will go to the lab for another immunoassay done by the machines then those non-negatives go to GC/MS. This is the only way they would tell you on the spot because where they collect the urine isn't where they test it usually. They send off all the urine to a central testing location if you live in a very large city or they may be shipped to a location that handles several cities. It will take a couple or several business days to process.