Jornal de Técnicas Analíticas e Bioanalíticas

Abstrato

Microemulsification-Based Method: Coupling with Separation Technique

Gabriela Furlan Giordano, Karen Mayumi Higa, Adriana Santinom, Angelo Luiz Gobbi, Lauro Tatsuo Kubota and Renato Sousa Lima

The outcomes described herein outline the potentiality of the microemulsification-based method (MEC) for development of rapid testing (point-of-use) technologies. MEC was recently proposed by these authors for analytical determinations wherein the detection is conducted in solution with naked eyes. It relies on effect of analyte over the colloid thermodynamics by changing the minimum volume fraction of amphiphile needed to generate microemulsions (MEs) (ΦME), which represents the analytical response of the method. We report in this paper the successfully coupling of MEC-based detection with gas diffusion separation. Such result extends the field of application of MEC in analytical sciences by improving its selectivity. One custom-designed module was constructed on PTFE for the separation measurements. It was utilized in combination with MEC for determining water in ethanol fuels using water/ n-propanol/oleic acid MEs and water-rich compositions. In this situation, accurate direct determinations by MEC are not possible. In addition, further studies on analytical performance and robustness of MEC by using n-propanol amphiphile are described. The method was robust as regards to deviations in dispersion preparing and changes in temperature. Concerning the analytical performance, the analytical curves presented wide linear range with limits of linearity of up to 70.00% v/v ethanol to water (ΦE). The limits of detection (S/N=3) were of 1.03%, 7.21%, and 0.68% v/v ΦE for compositions with water- (region A) and oil-rich (region C) domains as well as equal volumes of water and oil phases (region B), respectively. With respect to the regions A and B, the analytical performance stressed herein exhibited best linearity and comparable sensitivities when compared to these levels reached with ethanol amphiphile (our first publication on MEC) rather than n-propanol.