title: Serum analysis for potassium ions using a fibre optic sensor.
abstract: 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.
authors.affiliation: Department of Physical and Analytical Chemistry, University of Oviedo, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Pereiro García
authors.forename: F
authors.initials: F
authors.lastname: Alava Moreno
authors.forename: M E
authors.initials: ME
authors.lastname: Díaz García
authors.forename: A
authors.initials: A
authors.lastname: Sanz-Medel
authors.forename: R
authors.initials: R
authors.lastname: Narayanaswamy
mesh_terms: D015374:Biosensing Techniques; D002118:Calcium / Q000494:pharmacology; D005336:Fiber Optic Technology / Q000295:instrumentation*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D011188:Potassium / Q000097:blood*; D012964:Sodium / Q000494:pharmacology
chemical_list: D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium