The basic functionality of a breathalyzer is to take a given volume of an exhale and measure the concentration of a given particle as an indicator of intoxication. So long as an individual's results are greater than or equal to 0.08 then it becomes an unacceptable risk and they are considered intoxicated. If this process is going to test in a similar way, there is no need to test specific doses or profiles because the concentration isn't variable, it's a static amount. With alcohol, we don't consider weight, or what they had to drink, or how long they've drank so why should this be any different? All that needs to be defined is what the law considers a concentration which should represent a level where the risk reaches an unacceptable percentage.