The Chromatography Forum

of Delaware Valley

Analysis of Novel Psychoactive Substances by High-Performance Thin-Layer Chromatography

Over the past decade illicit drug distributors have been modifying the chemical structures of common drugs of abuse to create “designer drugs” to circumvent laws restricting their use. This has resulted in the synthesis of several different classes of novel psychoactive substances (NPSs) which include synthetic cannabinoids, cathinones, benzodiazepines, cathinones, phencyclidine analogues, tryptamines, and several others. The emergence of these NPSs that have variant and closely related structures of traditional drugs of abuse has caused crime labs to alter and search for new methods of analysis to identify and differentiate these compounds. Gas chromatography-mass spectrometry (GC-MS) has been and continues to be the gold standard for analysis of seized drugs in crime labs. However, this technique often falls short when differentiation of closely related compounds such as regioisomers need to be identified. Historically, traditional thin-layer chromatography (TLC) has been used for the analysis of seized drugs since it was a low-cost method for screening for a wide variety of compounds. Using traditional TLC, however, does not always provide a satisfactory level of sensitivity, resolution, or documentation to analyze these new compounds, many of which may be closely related structural isomers/analogues. This presentation will discuss the use of high-performance thin-layer chromatography (HPTLC) for the analysis of several classes of NPSs. A CAMAG automatic TLC system, HPTLC Silica gel 60 F254 20 x 10-cm plates and HPTLC-Platten 10 x 10-cm RP-18 WF254s plates were used in all analyses.  A CAMAG TLC visualizer was used to visualize developed plates and capture images with white light, 254 nm and 366 nm wavelengths. The methods show good intra- and inter-day precision (CV% <10%)  for RF values and detection limits in the range of 25-100 ng/band. The results suggest that HPTLC is a useful and fit-for-purpose method for separating many different classes of NPSs and can be easily introduced into casework processing for crime laboratories. HPTLC has demonstrated to be a green separation technique with adequate sensitivity, good resolution, along with providing proper documentation for peer review.