This in USA Today:
Greg Story, an atomic physics professor at the University of Missouri-Rolla, said the technology used in the scanner is not new.
Molecules energized by ultraviolet light emit a unique color spectrum that can be measured, Story said. Even when meth is created from different chemicals, the methamphetamine molecule would emit its own unique spectral signal, he says.
"I can’t speculate on (the scanner’s) accuracy, but yes, in principle, it’s absolutely possible," Story said.
Read the full story here.