Question about drug screen vs. drug test?

hey guys. i took a drug screen today (for pre-employment) for the first time so i don't know what it's all about. but i was told that a drug screen was diferent than a drug test. i just did a urine test and i thought it wass gonna be instant results but they said they were gonna said it to a lab or something. does this mean they are gonna to be more sensitive or is it gonna be the standard 50 ng/ml cuttoff? i don't get it. or are they going to start out doing gc/ms? help guys i am worried. i smoked like 2.5 weeks ago and all but i am worried that its gonna exeed the 15 ng/ml cuttoff with gc/ms?

 

lab tests are damn sensitive/accurate.

 

but it says i took a "drug screen." i looked on the web site of the lab i went to and if they were testing for pot the cut-off level is either 20 ng, 50 ng, or 100 ng depending on what my employer wants to check for. if tested positive, it would go through "marijuana confirmation" through gc/ms cuttoff level of 15 ng. well if my company chose to test me at 50 ng i would be ok right?

 

i took an at-home test where the cuttoff level was 50 ng and passed.

 

i think you'll be alright. if you fail just say you were at a concert where people were smoking marijuana.

 

2.5 weeks should do it. 3 weeks is a bit safer for future referrance.