 THC concentrations in the Intercept buffer ranged from 2.1 to 205.1 ng/mL.These concentrations represent about 1/2 to 1/3 the authentic THC concentrations in oral fluid because of the dilution by the blue liquid of the device.Two main limitations of oral fluid were 1. the amount of matrix collected is smaller when compared to urine and 2. the levels of drugs in urine are higher than in oral fluid.