I’ve used some of Carl’s kits for years.
I do not use them as the “final say” regarding meth presence on a property, but as additional evidence for the client to decide if he wants me to do Lab Testing for meth.
Every environmental test I do is actually a sampling for a Lab; I make sure it’s the lab that brings the good or bad news . . .  I certainly don’t want the final liability!
Several years ago, at a FL NACHI Convention, Mike Cooper offered Meth Certifications as a Door Prize, and I got one.  It’s a course in proper recognition and sampling techniques, followed by a test and certification to send samples in to his lab.
Anyone who is looking for documentation, I strongly recommend following up with:
Mike Cooper - Structural Narcotics Detection Service – had been in Kalispell MT but has recently moved to the Bozeman area.  He does not have his website or email set up again, but can be called.  He has a course you take before using his lab services, to be certified to do the sampling.  I’ve always been happy with his service; tell him Russ sent you!
SNDS
Mike Cooper
P.O. Box 556
Belgrade MT, 59714
406-250-3970