Pereiro García R, Alava Moreno F, Díaz García M E, Sanz-Medel A, Narayanaswamy R
Department of Physical and Analytical Chemistry, University of Oviedo, Spain.
Clin Chim Acta. 1992 Apr 30;207(1-2):31-40. doi: 10.1016/0009-8981(92)90148-j.
A fibre optic potassium ion sensor has been developed based on reflectance measurements of the pH-dependent chromogenic crown ether 'Takagi reagent' immobilized on the non-ionic polymeric resin Amberlite XAD2. The sensor response is in the 1.5-100 mM range with a detection limit of 0.25 mM K+. The selectivity factor over sodium is 20. The proposed sensor works with a reproducibility of +/- 0.8% at the 5 mM K+ level. Advantageous design features include ease of construction, simplicity of use, reversibility, short response time (approximately 1 min) and an optimum working pH range (7.0-8.0) for biological fluids. This optical sensor was applied successfully to the direct determination of potassium in human serum. Aqueous potassium standards containing 0.13 M NaCl and a buffer of pH 8 were used for calibration.
