Open Access Research Article Analytical & Bioanalytical Techniques J o u r n a l o f A n a l y tic a l & B io a n a l y ti c a l T e c h n i q u e s ISSN: 2155-9872 Giordano et al., J Anal Bioanal Tech 2015, 6:5 http://dx.doi.org/10.4172/2155-9872.1000261 Volume 6 • Issue 5 • 1000261 J Anal Bioanal Tech ISSN: 2155-9872 JABT, an open access journal Keywords: Point-of-care; Rapid test; Colloid; Interfacial tension; In situ analysis Abbreviations: ME: Microemulsion; AP: Amphiphile; W: Hydrophilic phase of dispersions; O: Hydrophobic phase of dispersions; Φ ME : Minimum volume fraction of amphiphile needed to get ME; Φ O : Volume fraction of oil to water; Φ E : Volume fraction of ethanol to water; Φ W : Volume fraction of water to ethanol; ΔΦ: Absolute error determined for Φ E Point-of-use devices represent currently a key ield in quantitative analytical sciences. hese platforms are low-cost, fast, portable, and simple to use eliminating the necessity for qualiied operators [1]. Rapid tests enable in-situ measurements presenting substantial social and economic implications at industry, environment, and medicine [2-9]. One potential output to perform point-of-use analyses is the accomplishment of the tests in solution with naked eye detection using disposable systems. It allows the determination of diferent analytes from the use of modiied nanomaterial [10]. Naked eye methods bypasses the use of instrumental readers, an essential feature for in-situ technologies. Furthermore, the analyses in solution surpass precision- related downsides when making the tests on substrates such as paper [6,9]. In this case, the diverse paper substrates that are employed to fabricate the devices afect the low rates and interactions with analytes [10]. his paper reports further investigations and application of the microemulsiication-based method (MEC), a point-of-use platform that was recently proposed by these authors [11]. It relies on solution- based-detection with naked eyes. In contrast with colorimetric tools [10], MEC response depends on colloid thermodynamics by relying on efect of analyte on the entropy of emulsions or Winsor systems. It changes the formation of thermodynamically stable dispersions, the microemulsions (MEs). he minimum volume fraction of amphiphile (AP) needed to get MEs (Φ ME ) for a ixed water-oil ratio expressed the analytical signal of the method. he generation of nanodroplets in MEs (transparent) allows the naked eye detection of Φ ME by monitoring the change of turbidity from the emulsions or Winsor systems (cloudy) as shown in Figure 1a. his cloudy-to-transparent conversion acts like a turning point in titrations, ensuring the visual measurement of Φ ME and, therefore, not only screening analyses (positive/negative data) as the most of naked eye colorimetry platforms [10] as well as precise quantitative analyses [11]. he response in colorimetry changes with the intensity of colour or tonality. Herein, subjective uncertainties by personal and surrounding conditions are observed [12]. MEC presents powerful aspects concerning the deployment of point- of-use tools. Such a method is straightforward, cheap, fast, portable, and provides precise analytical determinations with satisfactory precision, linearity, robustness, and accuracy. Lastly, volumes of approximately 20 µL for dispersions assure the visual measurement of Φ ME [11]. It contributes for a low sample consuming. he irst outcomes achieved by MEC were promising with respect to its analytical performance [11]. Direct analyses based on analytical *Corresponding authors: Renato Sousa Lima, Laboratory of Microfabrication , National Nanotechnology Laboratory, National Center for Research in Energy and Materials, Campinas , Sao Paulo 13083-970, Brasil, Tel: +55 19 3512 3566; E-mail: renato.lima@lnnano.cnpem.br Received July 07, 2015; Accepted July 21, 2015; Published July 28, 2015 Citation: Giordano GF, Higa KM, Santinom A, Gobbi AL , Kubota LT, et al. (2015) Microemulsiication-Based Method: Coupling with Separation Technique.J Anal Bioanal Tech 6: 261 doi:10.4172/2155-9872.1000261 Copyright: © 2015 Giordano GF, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract The outcomes described herein outline the potentiality of the microemulsiication-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) (Φ ME ), 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 ield 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 (Φ E ). The limits of detection (S/N=3) were of 1.03%, 7.21%, and 0.68% v/v Φ E 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 irst publication on MEC) rather than n-propanol. Microemulsification-Based Method: Coupling with Separation Technique Gabriela Furlan Giordano 1,2 , Karen Mayumi Higa 1,2 , Adriana Santinom 1,2 , Angelo Luiz Gobbi 1 , Lauro Tatsuo Kubota 2,3 and Renato Sousa Lima 1,2* 1 Laboratory of Microfabrication , National Nanotechnology Laboratory , National Center for Research in Energy and Materials, Campinas , Sao Paulo, Brasil 2 Instituto of Chemistry , State University of Campinas, Campinas, Sao Paulo, Brasil 3 Instituto National Science and Technology Bioanalytics, Campinas, Sao Paulo, Brasil