My intention was to use my Ketonix to calibrate the readings obtained on my cheap breathalyzer. This one:
But I’m giving up on this project after two weeks simply because the device is pretty much useless. When I originally purchased this breathalyzer I presumed it was inaccurate and probably not very reliable. But I thought at least if it was internally consistent it could be used to establish trends. Even this turns out to be wrong. The thing is not even consistent with itself. Any given readout on the device could represent anything within a range of 20 ppm or more.
For example, if I got successive readings of 3, 4, 5 it did NOT necessarily represent a trend upwards. Because of the amount of overlap of the possible ranges of results, 3, 4, 5 could just as well represent a trend downwards: 15ppm 10ppm 5ppm! The overlap of ranges was worst below 10ppm. For example, a 0 reading could be anything from 0 to 8ppm! For all practical purposes the range 4ppm to 10ppm is where most BrAce readings occur. Above 20ppm was almost as bad!
I know the concept of buying one of these cheap breathalyzers instead of spending $250 on a Ketonix is attractive to many. Unfortunately, I must report that it is totally useless for determining anything about the concentration of BrAce. Whatever numbers you blow on the device are just nonsense with no relevance to BrAce at all other than to indicate that it is present. Even then you might be blowing 0 on the device when your BrAce is actually as much as 8ppm!
So these things are just a toy. I had fun with mine for a couple months but now I know it wasn’t giving me any real information. 
