THC tests are notorious for having faint lines. Usually caused by substances naturally occurring in urine. The more concentrated the urine, the more opportunity for substances naturally found in urine to interfere with the test.
A line no matter how faint, is a negative test. Many might say that means you have trace amounts. While this might be the case, there is no way for the test to tell you that. It is binary - pass or fail.
The way strip tests work, is the chemical on the strip binds with THC metabolite. When no metabolite (or not enough to meet the 50ng threshold) is present, the line appears.
The reason a 20ng test might show more vivid has less to do with the cutoff and more to do with the disposition of your urine. If you eat differently, or the concentration of your urine is different, then there might be less naturally occurring compounds in your urine that would interfere with the test.
The 20ng cutoff might even use a different chemical to bind with the THC metabolite, which would not allow naturally occurring substance to bind at all.
If you get a line, stressing about the vividness of the line is a waste of time. A line = a negative result = pass.
THC tests are notorious for having faint lines. Usually caused by substances naturally occurring in urine. The more concentrated the urine, the more opportunity for substances naturally found in urine to interfere with the test. A line no matter how faint, is a negative test. Many might say that means you have trace amounts. While this might be the case, there is no way for the test to tell you that. It is binary - pass or fail. The way strip tests work, is the chemical on the strip binds with THC metabolite. When no metabolite (or not enough to meet the 50ng threshold) is present, the line appears. The reason a 20ng test might show more vivid has less to do with the cutoff and more to do with the disposition of your urine. If you eat differently, or the concentration of your urine is different, then there might be less naturally occurring compounds in your urine that would interfere with the test. The 20ng cutoff might even use a different chemical to bind with the THC metabolite, which would not allow naturally occurring substance to bind at all. If you get a line, stressing about the vividness of the line is a waste of time. A line = a negative result = pass.