Something new that appears on meth test reports since the release of NZS 8510:2017, is the term theoretical maximum. A lot of people bawk at these results and don’t understand what it means, which is understandable since its a new term and has literally just been thrown out there.
You’ll find theoretical max results on screening assessments reports which used composite sampling techniques. What it basically indicates is the worse case scenario for any one area which is sampled. For example if your report has a theoretical max of 5.5µg/sample then it’s possible one area could have a reading as high as 5.5µg, but this assumes all other sampled areas are zero, which is highly unlikely.
When field composite and lab composite techniques are used in the same screening assessment the theoretical max reading can be really high. This can freak people out a lot, however if you understand how these calculation are made then this can usually put you at ease.