| Grant number: | 14/24126-6 |
| Support Opportunities: | Regular Research Grants |
| Duration: | March 01, 2015 - February 28, 2017 |
| Field of knowledge: | Physical Sciences and Mathematics - Chemistry - Analytical Chemistry |
| Principal Investigator: | Renato Sousa Lima |
| Grantee: | Renato Sousa Lima |
| Host Institution: | Centro Nacional de Pesquisa em Energia e Materiais (CNPEM). Ministério da Ciência, Tecnologia e Inovações (Brasil). Campinas , SP, Brazil |
| Associated researchers: | Angelo Luiz Gobbi ; Diego Stéfani Teodoro Martinez ; Fernando Galembeck ; Lauro Tatsuo Kubota |
Abstract
This Project addresses an approach created at Microfabrication Laboratory in 2014. Called microemulsification-based method (MEC), it employs for the first time the thermodynamic stabilization of dispersions (microemulsification) to perform analytical determinations. The generation of nanodroplets in stable dispersions of microemulsions (MEs; transparent) allows complex chemical determinations by monitoring the change of turbidity from emulsions or Winsor systems (cloudy). More specifically, the MEC relies on effect of the analyte content over the dispersion entropy, affecting the microemulsification and, thus, the minimum volume fraction of amphiphile required to form ME that expresses the method analytical response. Unlike the colorimetry wherein the signal depends on color intensity, the measurement of the MEC analytical response is based on a binary chemical information, the cloudy-transparent conversion that occurs with the microemulsification process. This fact ensures accurate determinations simply through visual detection, bypassing any instrumental detection techniques. MEC combines simplicity, rapidity, low consumption of chemicals, and portability with high analytical performance taking into account parameters such as precision, linearity, robustness, and accuracy. Thereby, this approach is a promising alternative for the development of point-of-use technologies. So far, the reliability of the MEC was evaluated by analyzing water in ethanol fuel and monoethylene glycol in complex samples of liquefied natural gasprovided by Petrobras. The assays to analyze water demonstrated that the analytical performance depends on composition of the ME. It sums flexibility to the developed method. The tests to natural gas, in turn, showed the potential of the MEC for the analysis of complex matrices. The natural gas samples exhibited color, particulate material, high ionic strength, and diverse compounds including metals, carboxylic acids, and anions. These samples had a conductivity of up to 2,630 µS cm-1; the conductivity of pure monoethylene glycol was only 0.30 µS cm-1. Despite such downsides, the method allowed accurate measures bypassing steps such as extraction, preconcentration and dilution of the sample. In addition, the levels of robustness were promising. This parameter was assessed by investigating the effect of (i) deviations in volumetric preparation of the dispersions and (ii) changes in temperature and ionic strength over the analyte contents recorded by the method. This project specifically focuses on (i) investigation of the effect of diverse intervening factors (amphiphile and aqueous phase nature, temperature, and ionic strength) over the analytical performance and (ii) deployment of a microfluidic device integrating smartphone for accomplishment of MEC. Such steps will be performed with intent to get a better understanding about the developed method and to deploy a potential analytical tool for routine point-of-care experiments. The advent of the smartphone in the quantitative analytical chemistry is a current and frontier knowledge area. Their intrinsic characteristics such as portability, widespread usage, communication, and computation will contribute notoriously in the next years to develop lab-on-a-chip platforms capable of performing accurate, rapid, and automatic in situ experiments, eliminating the need for qualified operators (POC assays). In special, we believe the employment of the smartphone-coupled microfluidics to conduct the MEC is a promising way concerning the construction of these platforms. Besides their ideal features as rapid testing tool, such approach has high compatibility of automation in microchips incorporating smartphone as discussed in the current project. (AU)
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