Use of deep eutectic solvents in sustainable spectrophotometric and electroanalytical procedures

• Grant number: 24/04116-8
• Support Opportunities: Regular Research Grants
• Duration: August 01, 2024 - July 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Orlando Fatibello Filho
• Grantee: Orlando Fatibello Filho
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated researchers: Éder Tadeu Gomes Cavalheiro

Abstract

Our research group has been investigating the syntheses and applications of deep eutectic solvents (DES) in solid-liquid or liquid-liquid microextractions of various analytes in food, environmental, biological, and pharmaceutical samples. After separating the analyte from the sample matrix and pre-concentration, its determination can be made by spectrophotometry, digital image colorimetry using smartphones or by an electroanalytical technique. Conventional separation and preconcentration procedures usually involve high volumes of organic solvents, produce large amounts of waste and are generally time-consuming. DES have emerged as a greener and more sustainable alternative to replace organic solvents with high toxicity and volatility, in addition to being low-cost, easy to obtain and their preparation does not generate by-products (100% atomic economy). For these reasons, DES have been studied in several analytical applications. One of the numerous applications of DES involves the syntheses of metallic nanoparticles for use in electrochemical sensors. In our laboratories, we recently synthesized ultrasmall platinum nanoparticles (USPtNPs) with a diameter of 0.204 nm, which were used to modify a glassy carbon electrode for the determination of riboflavin. In the present proposal, the syntheses of several ultrasmall metal nanoparticles (USMNPs) such as Au, Ir, Pt, Ag, CeO2, Cu, Ni and iron oxides (Fe3O4 (magnetite) and Fe2O3 (hematite)) will be investigated, having different DES as reaction medium. Next, the nanoparticles will be used in the manufacture of electrochemical sensors for the determination of analytes in different matrices. In these studies, DES characterizations will be carried out using Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), as well as measurements of viscosity, conductivity, and water content. In addition, characterization of the nanoparticles will be carried out by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The elaborated sensors will be studied using voltammetric techniques (cyclic, differential pulse and square wave), amperometry and electrochemical impedance spectroscopy (EIS). Furthermore, in our group, electroanalytical procedures are also being developed directly in the DES. In other words, after microextraction and pre-concentration of the analyte under study, the DES itself serves as a supporting electrolyte. (AU)