Simple and Fast Analysis of LSD by Cyclic Voltammetry in Aqueous Medium

Tuesday, 3 October 2017: 16:00
Chesapeake J (Gaylord National Resort and Convention Center)
M. F. M. Ribeiro, E. N. Oiye, J. M. T. Katayama (Universidade de Sao Paulo - FFCLRP Departamento de Quimica), A. J. Ipólito (Universidade de São Paulo), and M. F. de Oliveira (Universidade de Sao Paulo - FFCLRP Departamento de Quimica)
Once the drug is apprehended, forensic laboratories must follow a procedure with chemical analysis aiming a confirmatory result. The application of electrochemical analysis inside forensic scenario has been widely explored, mainly in the analysis of illicit drug, due to the sensitivity and specificity acquired in a voltammetric measurement. Among these drugs, the psychedelic LSD (lysergic acid diethylamide) appears in seized blotters, and its apprehension is constant in global scale. LSD is a hallucinogenic drug, which concentration in blotter may show a discrepancy from 20 to 150 µg.

In this context, the development of a fast voltammetric method for quantification of LSD is proposed in the present study. It is important to highlight the use of an aqueous medium for the analysis, once the literature related to voltammetric studies for LSD, englobes organic medium in its majority.

In a conventional system with glassy carbon as the working electrode, the measurements were taken in KClO4 0.05 M as the supporting electrolyte. After an optimization study, the parameters fixed for the Cyclic Voltammetry were: potential range from 0.0 to 1.4 V and scan rate of 250 mV s-1. No pre concentration step was required.

The choice of KClO4 is based on a comparing study between others perchlorates salts (LiClO4, NH4ClO4, NaClO4) as supporting electrolyte. In addition, the pH of the solution was also verified, and the best condition for these measurements was pH 7.

The anodic peak observed in approximately potential of 0.9 V (Figure 01) is proportional to the concentration of LSD, what enables to stablish a linear equation y = 0.091 A L mol-1 x + 1.15x10-7 A for the quantification of LSD, in a linear range from 2.46 to 13.78 µmol L-1. The limits of detection and quantification are 0.73 and 2.46 µmol L-1, respectively, what enables detecting LSD in a concentration level of 4 µg per mL of the extraction solution. Besides, the use of an aqueous solution characterizes a less pollutant and less toxic methodology.

Then, the present work purposes a new methodology for quantification of LSD by Cyclic Votammetry, with an aqueous medium and also englobes a study about the electrochemical behavior of this drug under various experimental conditions.