Plataformas alternativas para sistemas eletroforéticos integrados com detecção condutométrica sem contato

• Autor(a) principal: Lobo Júnior, Eulício de Oliveira
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/6332
• topic: Eletroforese capilar; Microfluídica; Detecção condutométrica sem contato; Moldes em alto relevo; Poli (dimetilsiloxano) PMDS; Capillary electrophoresis; Microfluidics; Contactless conductivity detection; High relief masters; Poly (dimethylsiloxane) PDMS; QUIMICA::QUIMICA ANALITICA

This report describes the development of two alternative platforms for electrophoretic runs in microsystems. Firstly, the development of a hybrid capillary system that dispenses microfabrication steps is presented using fused silica capillaries interconnected by a commercial crossed shape interface. This hybrid system was coupled with contactless conductivity detector (C4D) to allow the determination of inorganic cations in biological samples. Electrokinetic sample injection was performed through gated mode approach for the first time in this arrangement. Operational parameters such as: (i) wave frequency and amplitude applied in C4D system, (ii) electrical potential applied in injection, (iii) injection time, (iv) detection point, (v) effect of capillary conditioning as well as and (vi) recovery percentage were extensively investigated and optimized. Better separations of cationic mixture containing NH4+, K+, Na+, Ca2+ and Mg2+ were achieved using a buffer system composed of 50 mM Lactic Acid, 20 mM Histidine and 3 mM 18-crown-6 on a capillary with effective length of 14.5 cm. . Addition of internal standard was used to ensure analytical reproducibility and allow the recording of merit figures. Linear behaviors were observed in concentration ranges between 10 and 100 M for NH4+, K+, Ca2+ e Mg2+, and 20-200 M for Na+. The limit of detection values calculated were 3.75 μM (NH4+), 3.70 μM (K+), 7.50 μM (Na+), 5.00 μM (Ca2+) and 5.35 μM (Mg2+). The concentration levels achieved for cations in biological samples ranged from 4,1 μM to 200 μM. Besides the hybrid system, this report also describes the development of an alternative methodology for the fabrication of high-relief masters for soft-lithography in poly(dimethylsiloxane) (PDMS) substrate. One of the innovative features makes reference to the use of low cost commercial photoresist from textile industry - poly(vinyl acetate) (PVAc) - which exhibits low toxicity. PVAc films were deposited on printed cirtuitry boards through the use of a homemade spincoater developed by desktop cooler, with rotation time control. This methodology allowed the production of high relief masters and PDMS channels with width and depth of 50 μm and 40 μm, respectively. Channels and masters profiles They were characterized with the following techniques: scan electron microscopy, perfilometry, optical and electrical. PDMS electrophoresis devices were successfully used for the separation of major inorganic cations.