Hand drawing of pencil electrodes on paper platforms for contactless conductivity detection of inorganic cations in human tear samples using electrophoresis chips.
This paper describes for the first time the fabrication of pencil drawn electrodes (PDE) on paper platforms for capacitively coupled contactless conductivity detection (C(4) D) on electrophoresis microchips. PDE-C(4) D devices were attached on PMMA electrophoresis chips and used for detection of K(+) and Na(+) in human tear samples. PDE-C(4) D devices were produced on office paper and chromatographic paper platforms and their performance were thoroughly investigated using a model mixture containing K(+) , Na(+) , and Li(+) . In comparison with chromatographic paper, PDE-C(4) D fabricated on office paper has exhibited better performance due to its higher electrical conductivity. Furthermore, the detector response was similar to that recorded with electrodes prepared with copper adhesive tape. The fabrication of PDE-C(4) D on office paper has offered great advantages including extremely low cost (< $ 0.004 per unit), reduced fabrication time (< 5 min), and minimal instrumentation (pencil and paper). The proposed electrodes demonstrated excellent analytical performance with good reproducibility. For an inter-PDE comparison (n = 7), the RSD values for migration time, peak area, and separation efficiency were lower than 2.5, 10.5, and 14%, respectively. The LOD's achieved for K(+) , Na(+) , and Li(+) were 4.9, 6.8, and 9.0 μM, respectively. The clinical feasibility of the proposed approach was successfully demonstrated with the quantitative analysis of K(+) and Na(+) in tear samples. The concentration levels found for K(+) and Na(+) were, respectively, 20.8 ± 0.1 mM and 101.2 ± 0.1 mM for sample #1, and 20.4 ± 0.1 mM and 111.4 ± 0.1 mM for sample #2.
Instituto de Química, Universidade Federal de Goiás, Goiânia, GO, Brazil.
Cyro L S
CL
Chagas
Instituto de Química, Universidade Federal de Goiás, Goiânia, GO, Brazil.
Lucas
L
Costa Duarte
Instituto de Química, Universidade Federal de Goiás, Goiânia, GO, Brazil.
Eulício O
EO
Lobo-Júnior
Departamento de Química, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Evandro
E
Piccin
Department of Food Science, University of Udine, Udine, Italy.
Nicolò
N
Dossi
Instituto de Química, Universidade Federal de Goiás, Goiânia, GO, Brazil.|Instituto Nacional de Ciência e Tecnologia em Bioanalítica (INCTBio), Campinas, SP, Brazil.
Wendell K T
WK
Coltro
D002412:Cations / Q000032:analysis*; D004553:Electric Conductivity; D004566:Electrodes; D046209:Electrophoresis, Microchip / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D010209:Paper; D013666:Tears / Q000737:chemistry*
D002412:Cations
Bioanalytical chemistry; Electrochemical detection; Microfluidic paper-based analytical devices; Paper-based electrochemical devices; Pencil drawn electrodes