Insight into response of ion-exchanger-based electrodes sensitive to highly lipophilic physiologically active amines

The influence of electrode conditioning algorithms, as well as the composition of the internal reference solution and measurement conditions on the analytical characteristics of an electrode reversible to cations of highly hydrophobic physiologically active amines, was studied in detail for the first time using the example of a verapamil-sensitive electrode with a polyvinyl chloride membrane containing tetrakis-(4-chlorophenyl) borate as a cation exchanger and plasticized with ortho-nitrophenyloctyl ether. It has been shown that to ensure the Nernstian slope of the electrode response, a low detection limit, and prevent the potential drift, the most important condition is to exclude the extraction of the amine molecular form from both the internal and the test solution into the membrane phase during measurements. The experimental data obtained are well described in terms of the dynamic diffusion model of the boundary potential and make it possible to formulate general principles for working with electrodes sensitive to ions of highly lipophilic physiologically active amines.

Automated summary

This study investigates the influence of electrode conditioning algorithms, internal reference solution composition, and measurement conditions on the analytical characteristics of an electrode reversible to cations of highly hydrophobic physiologically active amines. The experiment focuses on a verapamil-sensitive electrode with a polyvinyl chloride membrane containing tetrakis-(4-chlorophenyl) borate as a cation exchanger and plasticized with ortho-nitrophenyloctyl ether. The results show that preventing the extraction of the amine molecular form into the membrane phase is crucial for ensuring a Nernstian slope, low detection limit, and preventing potential drift.