The ion-selective membrane used to measure potassium is composed of?

The ion-selective membrane used to measure potassium ions is specifically designed to selectively bind to potassium while excluding other ions. Valinomycin, a cyclic ionophore, is particularly effective in this regard as it selectively binds potassium ions due to its structure that aligns with their size and charge. The inclusion of valinomycin in a gel or membrane allows for effective ion exchange, facilitating the measurement of potassium concentration based on the potential difference created by the selective binding of potassium ions.

This mechanism is crucial for the functionality of potassium-selective electrodes, as the response of the electrode will be influenced by the concentration of potassium in the solution it is measuring. Valinomycin’s ability to transport potassium ions across the membrane enhances the sensitivity and accuracy of potassium detection, making it an ideal choice for such applications.

In contrast, the other materials listed, such as high-borosilicate glass, polyvinyl chloride dioctylphenyl phosphonate, and calomel, do not possess the same selective binding characteristics for potassium ions and may not effectively contribute to the ion-selective methodology required for accurate potassium measurement.