Fentanyl is one of many possibles, and the test strips themselves may be bunk. The odds a 13 year old without a car is dropping off their pills at the gas chromatography machine in their STEM magnet school in the morning is pretty much nill.

Also worth noting in my state possessing kits design for testing for illegal drugs is a felony. [note: not legal advice]. No one reputable is going to risk a felony to sell drug testing kits for shitty margins.

https://www.azleg.gov/viewDocument/?docName=http://www.azleg...