A direct potentiometric titration method was applied to commercial and soil humic acids in order to determine their carboxyl and phenol group concentrations and apparent and intrinsic pK. In that context, acid-base properties of humic acids are interpreted by selective blocking of carboxylic and phenolic groups by esterification and acetylation. Differences in underivatized and derivatized HA’s...

A new approach to potentiometric sensing utilizing paper-based microfluidic sampling is studied in this work. A solid-contact ion-selective electrode and a solid-contact reference electrode are pressed against a filter paper into which the sample solution is absorbed. The filter paper acts simultaneously as a sampling unit and as a sample container during potentiometric sensing. The paper subst...

This report presents an optimization of potentiometric measurements withcitrate-selective electropolymerized poly(neutral red) electrodes. The optimal backgroundelectrolyte for these measurements is a TRIS buffer with nitrate at pH 8.5. The electrodesdescribed here exhibit stable and reproducible near-Nernstian response to citrates with alow detection limit of 6 × 10-6 M. Electrodes polymerized...

This article is focused on the determination of lidocaine hydrochloride as a local anaesthetic drug. A potentiometric method based on modified screen-printed and modified carbon paste ion-selective electrodes was described for the determination of lidocaine hydrochloride in different pharmaceutical preparations and biological fluids (urine and serum). It was based on potentiometric titration of...

In this paper, methods of sample preparation for potentiometric measurement of phenylalanine are presented. Basing on the spectrophotometric measurements of phenylalanine, the concentrations of reagents of the enzymatic reaction (10 mM L-Phe, 0,4 mM NAD, 2U L-PheDH) were determined. Then, the absorption spectrum of the reaction product, NADH, was monitored (maximum peak at 340 nm). The results ...

This article is focused on the determination of lidocaine hydrochloride as a local anaesthetic drug. A potentiometric method based on modified screen-printed and modified carbon paste ion-selective electrodes was described for the determination of lidocaine hydrochloride in different pharmaceutical preparations. It was based on potentiometric titration of lidocaine hydrochloride using modified ...

This article is focused on the determination of lidocaine hydrochloride as a local anaesthetic drug. A potentiometric method based on modified screen-printed and modified carbon paste ion-selective electrodes was described for the determination of lidocaine hydrochloride in different pharmaceutical preparations. It was based on potentiometric titration of lidocaine hydrochloride using modified ...