(https://www.nij.gov/topics/forensics/evidence/controlled-substances/Pages/improving-reliability-of-drug-tests-by-officers.aspx)
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The detection and identification of illegal drugs by police officers working in the field is a difficult process fraught with both legal and scientific challenges. Currently, officers typically do a “presumptive” test that involves breaking small vials of liquid reagents and observing what color they turn when they react with a suspect substance.
These widely used color tests are simple to use, but researchers and legal experts know the results can be questionable. Some reagents turn color when exposed not only to a particular illegal drug, but also to over-the-counter medications and a host of other substances. Also, some illegal drugs, such as BZP and MDMA (commonly referred to as ecstasy), are not detectable with color tests.
Richard Blair and his team of researchers at the University of Central Florida focused their NIJ-supported research on two issues: (1) developing a test that can presumptively identify drugs based on the luminescence that appears when the substances react with a certain class of metals and (2) creating a low-cost, reliable, and portable hand-held spectrometer that, in combination with a smartphone, can be used in the field to more accurately and specifically identify suspect substances.
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