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Measurement of sodium ion concentration in undiluted urine with cation-selective polymeric membrane electrodes after the removal of interfering compounds |
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| Authors: | Phillips Feyisayo Kaczor Kim Gandhi Neel Pendley Bradford D Danish Robert K Neuman Michael R Tóth Blanka Horváth Viola Lindner Ernö |
| Institution: | a Department of Biomedical Engineering, The University of Memphis, Memphis, TN 38152, USA b Department of Pediatrics, University of Tennessee Health Science Center Memphis, TN 38103, USA c Department of Biomedical Engineering, Michigan Technological University, Houghton, MI 49931, USA d Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, H-1111 Budapest, Hungary e Research Group for Technical Analytical Chemistry, Hungarian Academy of Sciences, Budapest University of Technology and Economics, H-1111 Budapest, Hungary |
| Abstract: | The measurement of sodium ion concentration in urine can provide diagnostic information and guide therapy. Unfortunately, neutral-carrier-based ion-selective electrodes show a large positive drift and loss in selectivity in undiluted urine. The extraction of electrically neutral lipids from the urine into the sensing membrane was suggested as the main source of the drift, loss of selectivity and the consequent incorrect concentration readings.In this work, (i) solvent-solvent extraction, (ii) membrane-immobilized solvent extraction and (iii) solid phase extraction were used to remove interfering compounds from urine samples. The “cleaned” urine samples were subsequently analyzed using a calixarene (sodium ionophore X)-based, solid-contact, sodium-selective electrode in a flow-through manifold. The solid-contact sodium sensors had excellent stability in cleaned urine and an acceptable bias compared to commercial clinical analyzers. |
| Keywords: | Undiluted urine Sodium ion monitoring Solid-contact ion-selective electrode Solvent-solvent and solid phase extraction Ionophore-based electrode |
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