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An electrophoretic ion analyzer for on-site autonomous water monitoring

journal contribution
posted on 2023-05-20, 22:50 authored by Liu, S, Pan, Z, Liang, Y, Li, F, Michael BreadmoreMichael Breadmore, Zhang, M
An on-site ion analyzer based on capillary electrophoresis with pressure-driven flow through injection and capacitively coupled contactless conductivity detection has been developed for field monitoring of cations and anions in environmental waters. Automated time-pressure based hydrodynamic injection provides stable pL-nL scale injection (RSD = 1.96%, n = 30). A mixture of 400 mM Bis-Tris, 400 mM MOPS and 2 mM 18-crown-6 is used as the background electrolyte to provide repeatable separations. A proprietary hydrophilic coated 25 μm id capillary is used to suppress the electroosmotic flow. Separations of anions (Cl-, NO3-, NO2-, SO42-, F- and PO43-) and cations (NH4+, K+, Na+, Ca2+ and Mg2+) are achieved by switching the polarity of the high voltage power supply in two individual runs. Signal fluctuations caused by the temperature or viscosity changes in on-site monitoring are corrected by on-line introduction of internal standards. RSDs of the migration time and the corrected peak height over ~35 h and 350 analysis cycles are < 4.06%. The LODs of inorganic ions are in the range of 2.1 μM (K+) to 6.8 μM (PO43-).  The feasibility for on-site water monitoring with this system has been validated by a standard Ion chromatography method with comparable results obtained.


Publication title

Journal of Chromatography A



Article number









School of Natural Sciences


Elsevier Science Bv

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Expanding knowledge in the chemical sciences