LNNano - Brazilian Nanotechnology National Laboratory

New studies and improvement on analysis velocity of method created in LNNano for point-of-use quantitative analyses

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Studies of intervening factors on the performance of the naked-eye microemulsification-based method and improvement on its analytical frequency

Karen M. Higa,a,b Camila L. de Camargo,a Gabriela F. Giordano,a,b Ivo P. O. Silva,a Angelo L. Gobbi,a Lauro T. Kubota,b Renato S. Lima*a,b

a Laboratório Nacional de Nanotecnologia (LNNano), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo 13083-100, Brasil.

b Instituto de Química, Universidade de Campinas, Campinas , São Paulo, 13083-970, Brasil.

* Corresponding author. E-mail: renato.lima@lnnano.cnpem.br

New investigations on the use of different amphiphiles and the improvement of the analytical frequency of the microemulsification-based method (MEC) are described in this paper. The results are important for a further understanding of the method (recently proposed by our group) and the development of attractive screening analysis platforms. MEC ensures precise determinations with naked-eye, representing a powerful alternative for point-of-use experiments. Herein, the influence of different surfactant-based amphiphiles (AP) on the MEC analytical performance was exhaustively evaluated for the first time, including ionic (sodium dodecylsulphate, SDS, and cetyl trimethylammonium bromide, CTAB) and neutral (triton X-100, TX-100, and tergitol NP-9, TNP-9) surfactants. The analytical performance was investigated for each one of the APs in three dispersion compositions according to merit figures such as precision, linearity, robustness, and accuracy that were obtained for the determination of ethanol (% v/v) in water and commercial alcoholic beverages. The data obtained for TNP-9 had poor robustness as a function of deviations in the oil phase volume and ionic strength. Additionally, the CTAB exhibited unsatisfactory robustness as a function of deviations in the temperature. In summary, TX-100 and SDS in A and B and CTAB in A lead to the best analytical performance for the determination of ethanol in alcoholic beverages. Furthermore, a new experimental mode was developed to increase the capacity of the MEC for rapidly analyzing various samples. Such routine was based on semi-quantitative analyses using a 96-deep well plate (DWP) and a multichannel micropipette to prepare the dispersions. This assembly allowed the naked-eye screening analysis of up to twelve samples with a resolution of eight concentration ranges in a single run without subjective uncertainties even after storing the DWP at 4 ºC for at least 5 weeks. This approach presents advantages such as rapidity, simplicity, portability, and low-cost representing, e.g., a promising alternative for the industry by taking up the challenges of continuous quality control in many industrial processes.

This article was published in Analytical Methods (RSC, DOI: 10.1039/C7AY00795G). This project has been conducted in Laboratório de Microfabricação (LMF, LNNano) in collaboration with the Universidade Estadual de Campinas.

Direct link: http://pubs.rsc.org/en/content/articlelanding/2014/ay/c7ay00795g#!divAbstract