http://www.erowid.org/psychoactives/...ng_info1.shtml
as per my previous post.....

many of the pass the drug test kits work by drinking so much water
that it brings the detection level below the detection point...
i dont know about jobs, but probation WATCHES you pee to make sure
you dont try to fool them, but thats pretty hard core for a job.

below is a link for all you need to know about drug tests
and kits that do and dont work....it also has alot of myth stuff that
has been spread thru the years... this is some serious recommended reading.
good luck!
http://www.erowid.org/psychoactives/...ting_faq.shtml