<P> The main metabolite excreted in the urine is 11 - nor - delta9 - tetrahydrocannabinol - 9 - carboxylic acid ( delta9 - THC - COOH ) . Most THC drug tests yields a positive result when the concentration of marijuana in urine exceeds 50 ng / mL . Urine Testing is an immunoassay based test on the principle of competitive binding . Drugs which may be present in the urine specimen compete against their respective drug conjugate for binding sites on their specific antibody . During testing , a urine specimen migrates upward by capillary action . A drug , if present in the urine specimen below its cut - off concentration , will not saturate the binding sites of its specific antibody . The antibody will then react with the drug - protein conjugate and a visible colored line will show up in the test line region of the specific drug strip . </P>
<P> The main metabolite excreted in the urine is 11 - nor - delta9 - tetrahydrocannabinol - 9 - carboxylic acid ( delta9 - THC - COOH ) . Most THC drug tests yields a positive result when the concentration of marijuana in urine exceeds 50 ng / mL . Urine Testing is an immunoassay based test on the principle of competitive binding . Drugs which may be present in the urine specimen compete against their respective drug conjugate for binding sites on their specific antibody . During testing , a urine specimen migrates upward by capillary action . A drug , if present in the urine specimen below its cut - off concentration , will not saturate the binding sites of its specific antibody . The antibody will then react with the drug - protein conjugate and a visible colored line will show up in the test line region of the specific drug strip . </P>
how many mg of thc to test positive
how many mg of thc to test positive
50 ng / mL
50 ng / mL