Dados do Trabalho

Título

ELECTROCHEMICAL DETECTION OF 25C-NBOH IN SEIZED BLOTTER PAPER SAMPLES

Introdução

The 25X-NBOHs, classified as New Psychoactive Substances, are thermolabile and their accurate determination can be a challenge using the gas chromatography technique, which can require additional steps in their analysis1. In this context, electrochemical sensors present some advantages such as portability, low cost, adequate selectivity, small sample volumes and can be miniaturized2.

Objetivos

Development of an electrochemical sensor for the rapid detection of 25C-NBOH.

Parte experimental

The stencil-printed electrochemical sensors were fabricated using conductive carbon and Ag/AgCl inks (Creative Materials®) on a phenolite substrate. The seized blotter paper samples were immersed in chloroform, followed by extraction in methanol. The CV technique was applied to study the influence of pH (2.0 – 12.0) and mass transport (varying the scan rate from 10 to 300 mV s-1) involved in the oxidation processes of 25C-NBOH in a potential range of 0.0 to 1.4 V. For quantification purposes, an analytical curve was built using the DPV in the concentration range of 5.0 to 100.0 μmol L-1. The selectivity of the sensor was evaluated by testing the response of 25B-NBOMe, 25B-NBOH, DOB, and LSD.

Resultados e Discussões

The pH study revealed that 25C-NBOH presented up to 3 irreversible and pH-dependent oxidation processes. The mass transport study revealed that all redox processes are mostly controlled by diffusion. The calibration curve presented two linear intervals (5.0-35.0 μmol L-1 and 35.0-100.0 μmol L-1). The limit of detection (LOD) and quantification (LOQ) were calculated as 2.68 μmol L-1 and 8.92 μmol L-1, respectively. Using the optimal conditions, the method was applied to the detection of 25C-NBOH in seized blotter papers obtained from SETEC/PF/MG. Using the standard addition method, it was determined 423 ± 59 μg of 25C-NBOH per blotter paper. The method presented adequate selectivity to detect 25C-NBOH when using the first oxidation process close to 0.37 V.

Conclusões

A low-cost and disposable electrochemical sensor for 25C-NBOH detection with adequate sensitivity and selectivity was developed, which allows both laboratory and field analysis

Referências e agradecimentos

1Neto, J.C. et al. Forensic Toxicology, v. 35, n.2, p. 408-414, 2017.
2Karadurmus, L. et al. TrAC Trends in Analytical Chemistry, v. 155, p. 116694, 2022.

CAPES, CNPq, FAPESP, NEE/Polícia Técnico-Científica de São Paulo, SETEC/Polícia Federal de Minas Gerais.

Palavras Chave

NBOHs, Electrochemical, NPS.

Arquivos