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PubMed · 3777438

Extended sensitivity for the calcium selective electrode.

R W Morton·J K Chung·J L Miller·J P Charlton·R S Fager
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Abstract

Sensitivity of calcium-selective electrodes heretofore has been limited to calcium concentrations above 10(-8) M in the absence of competing ions. We describe the use of calcium buffers to stabilize the free calcium in the reference electrode. Electrode calibration is linear to 10(-8) M and is curvilinear to 10(-11) M in the presence of 0.1 M ionic strength. Selectivity with respect to competing cations, magnesium, potassium, sodium, and hydrogen is preserved. Electrode response time is less than 2 s for small changes in calcium activity. Response range is linear over 9 log units of calcium activity. Potential-time stability is less than 10 mV/h at saturation currents. Although the silver-silver chloride terminals are photosensitive throughout the visible and near-ultraviolet regions, housing the reference and indifferent in opaque barrels avoids false photovoltaic response.

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BuffersCalciumElectrodesLightReference StandardsJournal ArticleResearch Support, U.S. Gov't, P.H.S.

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R W Morton, J K Chung, J L Miller, J P Charlton, R S Fager. 1986. Extended sensitivity for the calcium selective electrode.. https://doi.org/10.1016/0003-2697(86)90636-6

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