https://doi.org/10.1140/epjs/s11734-024-01154-x
Regular Article
Electrokinetic instability of a highly charged and weakly diffusing analyte in a buffer electrolyte near an ion-selective surface
1
Laboratory of micro- and nanoscale electro- and hydrodynamics, Financial University under the Government of Russian Federation, 125167, Moscow, Russian Federation
2
Laboratory of General Aeromechanics, Institute of Mechanics, Moscow State University, 119192, Moscow, Russian Federation
3
Institute of Mathematics, Mechanics and Computer Sciences, Southern Federal University, 344090, Rostov-on-Don, Russian Federation
4
Kuban State University, 350040, Krasnodar, Russian Federation
Received:
28
November
2023
Accepted:
20
March
2024
Published online:
4
April
2024
The preconcentration of a negatively charged analyte (proteins, DNA, biomolecules, etc.) in a buffer solution near a cation exchange membrane is an important phenomenon for biomedical applications. The initial minuscule concentration of the analyte is multiplied and the buffer anions are replaced by negatively charged analyte ions, ultimately leading to the formation of an asymmetric electrolyte consisting of highly charged and weakly diffusing particles of the analyte and buffer cations. The efficiency of preconcentration is limited by the electrokinetic instability of this electrolyte. The electrokinetic instability in an asymmetric electrolyte near a cation exchange electrical membrane was investigated theoretically using a model based on the Rubinstein—Zaltzman approach. Simple solutions have been found to describe the underlimiting and limiting modes, including their current–voltage characteristics and electroosmotic slips of the first and second kinds. An analytical formula was derived to estimate the instability threshold for various charge numbers and analyte diffusivities. Parameters were identified at which the theory predicts a significant reduction in the instability threshold and critical wave number. The analytical approach was supplemented by a numerical investigation of linear instability, which agrees well with the analytical predictions.
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© The Author(s), under exclusive licence to EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature 2024. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
