A novel method for the presumptive identification of heterocyclic amines of forensic interest using photoluminescent copper(i) iodide cluster compounds

Abstract

The use of color tests for the presumptive identification of illicit substances has been an important tool used by law enforcement to establish probable cause for decades. However, recently color tests have received negative media attention due to their inconsistent and subjective results that can sometimes lead to wrongful arrests. Although they have been fairly effective in testing common drugs, current color tests cannot combat the constant influx of novel psychoactive substances due to their failure to clearly distinguish similarly-structured compounds from one another. Common commercially available color tests can yield false positives for cocaine when testing diphenhydramine, indistinguishable results between cocaine and phencyclidine (PCP), and cannot easily detect benzylpiperazine (BZP). Here, we report the use of copper(I) iodide as a feasible drug-indicating agent for criminalistics and law enforcement use. Photoluminescent organometallic clusters formed with copper(I) iodide (CuI) and cyclic amines have been investigated for around 40 years, but with no known application toward forensic science. This work shows the practical implementation of copper(I) iodide to detect and identify various substances of forensic interest by photoluminescence spectral analysis of the resulting organometallic clusters. This novel method provides an innovative route for the presumptive identification of BZP, cocaine, PCP, fentanyl, opiates, piperazine-based designer drugs, and other heterocyclic alkaloids.