Voltammetric determination of Δ9-THC in glassy carbon electrode: An important contribution to forensic electroanalysis

Abstract

A new voltammetric method for the determination of Δ(9)-tetrahydrocannabinol (Δ(9)-THC) is described. The voltammetric experiments were accomplished in N-N dimethylformamide/water (9:1, v/v), using tetrabutylammonium tetrafluoroborate (TBATFB) 0.1mol/L as supporting electrolyte and a glassy carbon disk electrode as the working electrode. The anodic peak current was observed at 0.0V (vs. Ag/AgCl) after a 30s pre-concentration step under an applied potential of -1.2V (vs. Ag/AgCl). A linear dependence of Δ(9)-THC detection was obtained in the concentration range 2.4-11.3ng/mL, with a linear correlation coefficient of 0.999 and a detection limit of 0.34ng/mL. The voltammetric method was used to measure the content of Δ(9)-THC in samples (hemp and hashish) confiscated by the police. The elimination of chemical interferences from the samples was promptly achieved through prior purification using the TLC technique, by employing methanol/water (4:1, v/v) as the mobile phase. The results showed excellent correlation with results attained by HPLC.

Voltammetric Determination of Cocaine in Confiscated Samples Using a Carbon Paste Electrode Modified with Different [UO2(X-MeOsalen)(H2O)]·H2O Complexes

“…Balbino et al investigated the electrochemical behavior of delta 9 -tetrahydrocannabinol (Δ 9 -THC), the psychoactive substance in hemp, by cyclic and linear sweep voltammetry using a glassy carbon working electrode [10]. Electrochemical techniques offer several advantages: (i) they are sensitive, accurate, and precise; (ii) they enable one to work with a large range, relative instrumentation and materials; (iii) they can be applied to colored materials and samples containing dispersed solid particles [7,8]; (iv) they provide rapid response; (v) and they allow for analysis of the irreversible electrooxidation of the tertiary amine present in the cocaine molecule [11].…”

Voltammetry of Immobilized Particles of Cannabinoids

“…The forward and backward components of these responses were similar and indicate an irreversible electrode reaction. It was suggested that the peak of THC originates from the one-electron, one-proton oxidation of the phenol group to form the phenoxy radical [21], as in the case of other phenols [37,38]. The radical generally decays via rapid polymerization [39,40].…”

“…The cannabinoids form a group of C 21 terpenophenolic compounds unique to the plant Cannabis sativa L. To date, more than 85 different cannabinoids have been isolated from the cannabis plant. Of these, the most important are: cannabinol (CBN), cannabidiol (CBD) and the psychoactive component delta-9-tetrahydrocannabinol (THC) (see Scheme 1) [1][2][3].…”

“…Consequently, a group of authors recently developed an electrochemical method for detection of THC in saliva, which could provide a roadside testing for cannabis in drug drivers [19,20]. Furthermore, voltammetric determination of THC dissolved in dimethylformamide was described and applied to measure the content of THC in hemp and hashish [21].…”

Applications of electrochemical sensors: Forensic drug analysis

“… 9 -THC can be directly detected by monitoring the anodic peak at 0 V vs Ag/AgCl on a glassy carbon electrode. 18,49,50 This research presented for the first time a direct electrochemical oxidation sensor which could provide meaningful voltammetric signatures for synthetic cannabinoids thus allowing the detection of these NPS in seized materials and biological samples, as shown in Figure 4.…”