We present an improved Na+-selective liquid membrane electrode for measurement of Na+ concentrations in both undiluted serum and urine. The values for urinary Na+ obtained with the ion-selective electrode agree well with those obtained with the flame photometer. The correlation gives a standard residual deviation of ± 2.7 mmol/L over the Na+ range of 25-280 mmol/L. In serum, this direct potentiometry yields Na+ concentrations 5.4% (SD 1.1%) higher than those obtained by atomic spectrometry and a standard residual deviation of ± 1.1 mmol/L. Correlation of these values for the volumes of protein and lipid leads to potentiometric values 1.2% (SD 0.7%) lower than those by flame photometry (residual standard deviation: ± 1.0 mmol/L). Other factors that possibly contribute to this discrepancy are discussed.
CITATION STYLE
Anker, P., Jenny, H. B., Wuthier, U., Asper, R., Ammann, D., & Simon, W. (1983). Potentiometry of Na+ in undiluted serum and urine with use of an improved neutral carrier-based solvent polymeric membrane electrode. Clinical Chemistry, 29(8), 1508–1512. https://doi.org/10.1093/clinchem/29.8.1508
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