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.
The researchers developed a fluorometer by making a small black box with a 3-D printer. They then used a low-cost cold cathode lamp (to provide the fluorometer’s excitation light) and powered the system with a rechargeable lithium ion battery. The unit allows investigators to identify powders and other substances using a paper test strip soaked in copper iodide. Certain classes of drugs react with the copper by giving off a fluorescent light signature unique to the drug.
An investigator in the field can photograph the fluorescence spectrum with a smartphone, upload the result to the Cloud, compare it to known spectra in an online database, and determine what the substance is. “This method has less false positives and false negatives than the spot [color] tests as it does not allow multiple interpretations of the result,” the researchers said.
Officers do not need to undergo extensive training to use the system, which is important given the widespread use of presumptive drug testing in the field. For some drugs that are difficult to detect, the study has “successfully managed to overcome the shortcomings of the color spot tests that are presently used religiously in most of the crime labs across the country,” the researchers said.
“Overall,” the researchers concluded, “this project has shown promising results in identifying distinctly and definitively the trace amounts of substances of abuse by using the florescent indicators.”
About this Article
The research discussed in this article was performed under NIJ cooperative agreement 2012-R2-CX-K005, awarded to the University of Central Florida.
This article is based on the grant report Transition Metal Cluster Compounds for the Fluorescent Identification and Trace Detection of Substances of Abuse (pdf, 11 pages) by Richard G. Blair, Ph.D.The work described in the article was performed under NIJ grant number , awarded to the University of Central Florida.