A Comparative Study Between Two Different Conventional Working Electrodes for Detection of Δ9-Tetrahydrocannabinol Using Square-Wave Voltammetry: a New Sensitive Method for Forensic Analysis

Marijuana is a widely consumed illicit drug. Therefore, drug dealers have sought new ways to mask its forensic (spot test) analysis. In this article we describe a methodology for delta-9-tetrahydrocannabinol (Delta(9)-THC) detection by square-wave voltammetric (SWV) analysis in organic medium (N,N-dimethylformamide) using tetrabutylammonium tetrafluoroborate (TBATFB) as supporting electrolyte, and glassy carbon and platinum disc as working electrode. Applying a potential of -0.5 +/- 0.01 V vs. Ag/AgCl, KCl(sat), we detected a well-defined anodic peak current after the pre-concentration step; Delta(9)-THC detection presented linear dependence at concentrations ranging from 1.0 x 10(-9) mol L-1 to 2.2 x 10(-8) mol L-1, with a linear correlation coefficient 0.999 and a detection limit of 6.2 x 10(-10) mol L-1, using the glassy carbon disc working electrode. These results confirm that optimized SWV technique using glassy carbon disc working electrode enables qualitative analysis of Delta(9)-THC at concentrations higher than 1.0 nmol L-1.