thanks FBR. Is the cutoff mean they don't test below that? I am confused. 50 on a UI means anything above is positive. On a gc/ms is the standard that anything above 20 is positive? i have heard reports saying it is 15. Please enlighten me as I am trying to do some calculations from these past two weeks to see if it's looking good for me to pass the gc/ms if they test for all substances again regardless of whether they showed up neg or non-neg on the UI (which you said they do). Thanks.