As is stated here multiple times, if you pass your at home panel you will pass the lab. All the lab does is screen a 5 (or however many they wish) panel on your urine. If any of those is positive, then it will be sent over to the GC/MS to confirm the precise level of toxin(s). It is not in their best interest to run a confirmation on negative screens.

After being testing negative for 3 weeks, I smoked ~3g over the weekend of the 27th. I'm 6'1" and 290lbs and just tested negative on a 50ng panel today the 3rd. Hope this eases your mind.
2clean Reviewed by 2clean on . At home drug test I am writing for peace of mind. I am 5'3 about 220 lbs (a fatty) and I am not a regular smoker. I last smoked on 4/20/13 and have not been around or had anything else after that. I would say on average maybe smoked once a week for about two months (if even that). It is more of an occasional use than anything. I have an opportunity to take a job and I will be drug testing next week, probably Monday. That would be 2 weeks after I last smoked. I have taken two at home drug tests, one on Tuesday Rating: 5