Supramolecular Atropine Potentiometric Sensor

A supramolecular atropine sensor was developed, using cucurbit[6]uril as the recognition element. The solid-contact electrode is based on a polymeric membrane incorporating cucurbit[6]uril (CB[6]) as an ionophore, 2-nitrophenyl octyl ether as a solvent mediator, and potassium tetrakis (4-chlorophenyl) borate as an additive. In a MES-NaOH buffer at pH 6, the performance of the atropine sensor is characterized by a slope of (58.7 ± 0.6) mV/dec with a practical detection limit of (6.30 ± 1.62) × 10−7 mol/L and a lower limit of the linear range of (1.52 ± 0.64) × 10−6 mol/L. Selectivity coefficients were determined for different ions and excipients. The obtained results were bolstered by the docking and spectroscopic studies which demonstrated the interaction between atropine and CB[6]. The accuracy of the potentiometric analysis of atropine content in certified reference material was evaluated by the t-Student test. The herein proposed sensor answers the need for reliable methods providing better management of this hospital drug shelf-life while reducing its flush and remediation costs.

Semiautomatic and fully functional electrochemical microanalyzer BO-05 suitable for scientific, didactic, and analytical applications: The use in the potentiometric analysis of drugs

This article presents the potentiometric method of determination of chlorides using the original BO-05 electrochemical microanalyzer. The quantification of chlorides is one of the frequently performed methods, both in the indirect determination of active pharmaceutical ingredients (API) and impurities in pharmaceutical raw materials, pharmacopoeial substances or pharmaceutical formulations as well. Successfully validated method was used to the analysis of chlorides in the preparations containing verapamil hydrochloride in form of tablets Staveran® and Verapamil®. The mean content of the studied API calculated to one tablet was close to the declared and equal to 123.6±1.5 mg and 122.6±1.1 mg, respectively. The presence of excipients have no significant impact on the final results. Thus shown that the electrochemical microanalyzer BO-05 is suitable for scientific, didactic and analytical applications.

A Novel Multi-Ionophore Approach for Potentiometric Analysis of Lanthanide Mixtures

This work aims to discuss quantification of rare earth metals in a complex mixture using the novel multi-ionophore approach based on potentiometric sensor arrays. Three compounds previously tested as extracting agents in reprocessing of spent nuclear fuel were applied as ionophores in polyvinyl chloride (PVC)-plasticized membranes of potentiometric sensors. Seven types of sensors containing these ionophores were prepared and assembled into a sensor array. The multi-ionophore array performance was evaluated in the analysis of Ln3+ mixtures and compared to that of conventional monoionophore sensors. It was demonstrated that a multi-ionophore array can yield RMSEP (root mean-squared error of prediction) values not exceeding 0.15 logC for quantification of individual lanthanides in binary mixtures in a concentration range 5 to 3 pLn3+.

Potentiometric sensor for lead ions determination

One of the sensitive and inexpensive methods used for the analysis of water bodies is the ionometry, the development of which is associated with the introduction of new ion-selective electrodes into the practice of potentiometric analysis. An optimized composition of the membrane for the manufacturing of a zinc-selective electrode based on polyvinyl chloride modified with 2-mercaptobenzthiazole (MPVC) is proposed with the following ratio of ingredients (in wt. %): Polyvinyl chloride - 31.7; dioctyl sebacate - 66.3; potassium tetra-p-chlorophenylborate - 0.5; MPVH - 1.5. The working range of pH was established with a minimum potential drift, which was 1.5 - 3. The slope of the electrode function was calculated as 30.1 ± 0.3 mV. According to the dependence of the electrode potential for the selected composition of the membrane on the logarithm of the zinc ion concentration, it was found that the proposed model of the electrode operates in the concentration range of 1∙10-5 - 1∙10-1 mol / L, with a detection limit of 0.65 mg / l. The stabilization time of the potential within 1 mV was 15 - 20 s. The potentiometric coefficients of the selectivity of the zinc selective electrode with respect to various ions have been determined. The conditions for the determination of zinc using the obtained sensor in alloys and wastewater were proposed. The electrode with the membrane based on polyvinyl chloride modified with 2-mercaptobenzthiazole can be used as an alternative to the industrial electrode XC-Zn-001 for the determination of zinc ions in various objects. The obtained experimental data was close in accuracy to the results obtained by the atomic absorption methods, as well as the ionometry using the industrial electrode. In conclusion, the electrode with the membrane based on polyvinyl chloride modified with 2-mercaptobenzthiazole can be used as an alternative to XC-Zn-001.

Masking Ability of Various Metal Complexing Ligands at 1.0 mM Concentrations on the Potentiometric Determination of Fluoride in Aqueous Samples

Fluoride is a common anion present in natural waters. Among many analytical methods used for the quantification of fluoride in natural waters, potentiometric analysis is one of the most widely used methods because of minimum interferences from other ions commonly present in natural waters. The potentiometric analysis requires the use of ionic strength adjusting buffer abbreviated as TISAB to obtain accurate and reproducible data. In most of the reported literature, higher concentrations of strong metal chelating ligands are used as masking agents generally in the concentration range of 1.0 to 0.01 M. In the present study, effectiveness of the masking agents, phosphate, citrate, CDTA ((1,2-cyclohexylenedinitrilo)tetraacetic acid), EDTA (ethylenediaminetetraacetic acid) HE-EDTA ((hydroxyethyl)ethylenediaminetriacetic acid)), triethanolamine, and tartaric acid at 1.0 mM in TISAB solutions was investigated. The experimental data were compared with a commercially available WTW 140100 TISAB solution as the reference buffer. According to the experimental data, the reference buffer always produced the highest fluoride concentrations and the measured fluoride concentrations were in the range of 0.611 to 1.956 mg/L. Out of all the masking agents investigated, only CDTA performed marginally well and approximately a quarter of the samples produced statistically comparable data to the reference buffer. All the other masking agents produced significantly low concentrations compared to the reference buffer. The most probable reasons for the underestimation of fluoride concentrations could be shorter decomplexing time and lower masking agent concentrations.