Measurement of sodium ion concentration in undiluted urine with cation-selective polymeric membrane electrodes after the removal of interfering compounds.
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.
Phillips
Feyisayo
F
Department of Biomedical Engineering, The University of Memphis, Memphis, TN 38152, USA.
Kaczor
Kim
K
Gandhi
Neel
N
Pendley
Bradford D
BD
Danish
Robert K
RK
Neuman
Michael R
MR
Tóth
Blanka
B
Horváth
Viola
V
Lindner
Ernö
E
D002138:Calibration; D002412:Cations / Q000652:urine; D002624:Chemistry, Clinical / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D006801:Humans; D017736:Ion-Selective Electrodes; D008055:Lipids / Q000302:isolation & purification / Q000652:urine; D008567:Membranes, Artificial; D011108:Polymers / Q000737:chemistry*; D012015:Reference Standards; D012680:Sensitivity and Specificity; D012964:Sodium / Q000652:urine*; D052616:Solid Phase Extraction; D012996:Solutions; D012997:Solvents / Q000737:chemistry
D002412:Cations; D008055:Lipids; D008567:Membranes, Artificial; D011108:Polymers; D012996:Solutions; D012997:Solvents; D012964:Sodium