Potentiometric potassium selectivity of polymer membrane electrodes prepared with organo‐phosphine ligands

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Abstract
Potassium ion‐selective electrodes based on a new type of phosphine oxide compounds were prepared. The electrode based on tert‐butyl‐3‐p‐tolyl phosphine oxide cyclohexene gave a linear response with a Nernstian slope of 60 mV per decade within the concentration range 10−1–10−5 M KCl. The electrode exhibited good selectivity for potassium with respect to alkali, alkaline earth and other metal ions. The content of potassium ion in some plant and soil samples was determined using the prepared electrode and flame photometry. The electrode gave results very similar to those of flame photometry. Routine use of ion‐selective potentiometry for potassium determination can thus be recommended for plant and soil analysis.