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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Cocaine electrooxidation behavior, mechanism, and kinetics on a carbon paste electrode chemically modified with a cobalt or copper Schiff base complex

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Castro, Alex Soares [1] ; de Azevedo, Larissa Silva [2] ; Bruni, Aline Thais [3, 1] ; Teles de Menezes, Matheus Manoel [4] ; Dockal, Edward Ralph [5] ; de Oliveira, Osmair Vital [4] ; Ferreira, Bruno [1] ; de Oliveira, Marcelo Firmino [1, 2]
Total Authors: 8
[1] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Quim, Grp Eletroquim Eletroanalit & Quim Forense, Ave Bandeirantes 3900, Ribeirao Preto, SP - Brazil
[2] Univ Sao Paulo, Inst Quim Sao Carlos, Ave Trabalhador Sao Carlense 400, Sao Carlos, SP - Brazil
[3] Inst Nacl Ciencia & Tecnol Forense INCT Forense, Ribeirao Preto, SP - Brazil
[4] Inst Fed Educ Ciencia & Tecnol Sao Paulo, Campus Catanduva, Catanduva, SP - Brazil
[5] Univ Fed Sao Carlos, Ctr Ciencias Exatas & Tecnol, Dept Quim, BR-13565905 Sao Carlos, SP - Brazil
Total Affiliations: 5
Document type: Journal article
Source: FORENSIC CHEMISTRY; v. 26, DEC 2021.
Web of Science Citations: 0

Cocaine is one of the most abused drugs worldwide. Therefore, it is crucial to develop and improve cocaine identification techniques. This article describes two new electrodes chemically modified with ({[}Co((+/-)-t3MeOsalcn)] or ({[}Cu((+/-)-t-3MeOsalcn)] and their use in free-base cocaine (FB) and cocaine hydrochloride (HC) identification. The electrodes were not active toward FB, but cyclic voltammetry analysis revealed an increase of 0.1 V (vs Ag/AgCl) (Eoxi) for HC. The square-wave voltammetry results showed that FB@({[}Cu((+/-)-t-3MeOsalcn)] and HC@({[}Cu((+/-)-t-3MeOsalcn)] presented higher amperometric sensitivity than FB@({[}Cu((+/-)-t-3MeOsalcn)] and HC@({[}Cu((+/-)-t-3MeOsalcn)]. The limit of detection (LOD) and the limit of quantification (LOQ) for FB@ ({[}Cu((+/-)-t-3MeOsalcn)] were 0.61 mu mol.L- 1and 2.04 mu mol.L- 1, respectively. As for HC@({[}Cu((+/-)-t-3MeOsalcn)] the LOD and the LOQ were 0.58 mu mol.L-1 and 1.92 mu mol.L- 1, respectively. The higher chemical stability of the cocaine@({[}Cu((+/-)-t-3MeOsalcn)] complexes and the lower binding energy of FB and HC with ({[}Cu((+/-)-t3MeOsalcn)] predicted by theoretical calculations explain the results of the voltammetric analyses. Moreover, the topographic and compositional results confirmed that HC adsorbed onto the surface of the electrodes chemically modified with {[}Co((+/-)-t-3MeOsalcn)] or ({[}Cu((+/-)-t-3MeOsalcn)]. Overall, our results demonstrated that the electrodes chemically modified with {[}Co((+/-)-t-3MeOsalcn)] or ({[}Cu((+/-)-t-3MeOsalcn)] developed in this study have promising application in cocaine detection and quantification. At the end of the study, we propose a schematic mechanism for the HC oxidation process at the modified electrodes. (AU)

FAPESP's process: 16/23825-3 - Development of voltammetric sensors for determination of cocaine and delta-9-tetrahydrocannabinol in samples seized by the police
Grantee:Marcelo Firmino de Oliveira
Support Opportunities: Regular Research Grants
FAPESP's process: 16/01447-7 - Development of chemically modified electrodes (NDEs) with complexes of Schiff base for determination of cocaine: voltammetric studies and application of density functional theory (DFT)
Grantee:Alex Soares Castro
Support Opportunities: Scholarships in Brazil - Scientific Initiation