Hydrodynamic injection on electrophoresis microchips using an electronic micropipette
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2017-01
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Here we report for the first time the use of an electronic micropipette as hydrodynamic (HD) injector for microchip electrophoresis (ME) devices. The micropipette was directly coupled to a PDMS device, which had been fabricated in a simple cross format with two auxiliary channels for sample volume splitting. Sample flow during the injection procedure was controlled in automatic dispenser mode using a volume of 0.6 µL. Channel width and device configuration were optimized and the best results were achieved using a simple cross layout containing two auxiliary channels with 300 µm width for sample splitting. The performance of the HD injector was evaluated using a model mixture of high-mobility cationic species. The results obtained were compared to the data obtained via electrokinetic (EK) injection. Overall, the HD provided better analytical performance in terms of resolution and injection-to-injection repeatability. The relative standard deviation (RSD) values for peak intensities were lower than 5% (n=10) when the micropipette was employed. In comparison with EK injection, the use of the proposed HD injector revealed an unbiased profile for a mixture containing K+ and Li+(300 µmol L−1 each) over various buffer concentrations. For EK injection, the peak areas decreased from 2.92 ± 0.20–0.72 ± 0.14 V s for K+ and from 1.30 ± 0.10–0.38 ± 0.10 V s for Li+ when the running buffer increased from 20 to 50 mmol L−1. For HD injection, the peak areas for K+ and Li+ exhibited average values of 2.48±0.07 and 2.10±0.06 V s, respectively. The limits of detection (LDs) for K+, Na+ and Li+ ranged from 18 to 23 µmol L−1. HD injection through an electronic micropipette allows to automatically dispense a bias-free amount of sample inside microchannels with acceptable repeatability. The proposed approach also exhibited instrumental simplicity, portability and minimal microfabrication requirements.
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Automatic dispensing, Bias-free sample injection, Microfluidic transport, Portable instrumentation
Citação
GABRIEL, Ellen F. M. et al. Hydrodynamic injection on electrophoresis microchips using an electronic micropipette. Talanta, (Oxford), v. 162, p. 19-23, 2017. DOI: 10.1016/j.talanta.2016.09.046. Disponível em: https://www.sciencedirect.com/science/article/pii/S0039914016307172?via%3Dihub. Acesso em: 8 ago. 2024.