The Use of an Acylhydrazone-Based Metal-Organic Framework in Solid-Contact Potassium-Selective Electrode for Water Analysis

A solid-contact ion-selective electrode was developed for detecting potassium in environmental water. Two versions of a stable cadmium acylhydrazone-based metal organic framework, i.e., JUK-13 and JUK-13_H2O, were used for the construction of the mediation layer. The potentiometric and electrochemical characterizations of the proposed electrodes were carried out. The implementation of the JUK-13_H2O interlayer is shown to improve the potentiometric response and stability of measured potential. The electrode exhibits a good Nernstian slope (56.30 mV/decade) in the concentration range from 10−5 to 10−1 mol L−1 with a detection limit of 2.1 µmol L−1. The long-term potential stability shows a small drift of 0.32 mV h−1 over 67 h. The electrode displays a good selectivity comparable to ion-selective electrodes with the same membrane. The K-JUK-13_H2O-ISE was successfully applied for the determination of potassium in three certified reference materials of environmental water with great precision (RSD < 3.00%) and accuracy (RE < 3.00%).

Ion Selective Electrode Mediated by Transfer Layer of Graphene Oxide for Detection of Ca2+ with Highly Sensitivity and Selectivity

A Ca2+ selective microelectrode was proposed through electrodepositing graphene oxide (GO) on carbon fiber as an efficient ion-electron transfer layer. The gold leaves were further synthesized at GO surface to increase the specific surface area and provide a substrate for assembly of the specific ligands for Ca2+. GO with negative charges greatly facilitated the electron transfer process from the recognition center to electrode surface, resulting in the apparently enhanced sensitivity towards Ca2+. Moreover, the developed ion-selective microelectrode exhibited good selectivity to Ca2+, and a good linear range from 10 μM to 10 mM with a detection limit of 5.91±0.46 μM.

The Ionic Associate of Metamizole as an Electrode-Active Component of a PVC Plasticized Membrane Electrode

The technology for manufacturing a film membrane of the metamizole-selective electrode containing ion associate metamizole-octadecylammonium ODAH+MT− as an electrode active component (EAC) has been proposed. The main potentiometric characteristics of the metamizole-selective electrode have been determined. The expediency of the proposed design of the metamizole selective electrode for the determination of metamizole in dosage forms has been substantiated. The best composition of the membrane (wt.%) of the metamizole-selective electrode has corresponded to: ODAH+MT−—5.3; 2-nitrophenyloctylether—63.1; poly(vinyl chloride)—31.6. Electrode-active component in the membrane phase functions as an ion associate ODAH+MT−. Potentiometric characteristics of metamizole-selective electrode have been determined, which corresponded to: linear range 1 × 10−2–1 × 10−4 with limit of detection 4.58 × 10−5 M, electrode function slope −48.5 mV/dec., working interval pH 4.5–7.3, response time 60 s. The potentiometric coefficients of selectivity of the metamizole-selective electrode with respect to various ions have been determined. The possibility of determining metamizole in a medicinal product has been tested. The results of the analyses show good agreement between the two methods (relative error less than 7.0%) with coefficients of variation less than 5% for MT-SE and iodometric methods.

Comparative between Ammonia Ion Selective Electrode and Dye Binding Method to study effect of Processing Methods on Protein Content of Plain Yogurt

In this study, two analytical methods were used to determinate the protein, the ammonia ion selective electrode method and dye binding method using orange G and the spectrophotometer at λmax 478 nm by determining the linearity, accuracy, precision, limit of detection and limit of quantitation of each. In comparison, the dye binding method was chosen for its accuracy, repeatability, sensitivity (LOD, LOQ) and speed of performance. After that, it was applied to samples of prepared plain yogurt to study effect of different properties (source, heat treatment and type) of used milk on protein content of plain yogurt.

Assessment of Fluoride and pH Levels in a Range of Ready-to-Drink Children’s Beverages Marketed in Malaysia

This study aimed to determine the fluoride and pH levels of beverages likely to be consumed by children in Malaysia and to estimate daily fluoride intake from consumption of these beverages. A convenience sampling of 120 ready-to-drink beverages were purchased and categorised into 11 groups (UHT recombined milk, fresh milk [pasteurised], cultured milk [probiotic], yogurt beverages, fresh fruit juices, fruit flavoured beverages, soy-based beverages, malt-based beverages, tea, carbonated beverages and bottled waters). Fluoride concentration was measured using a fluoride ion-selective electrode while the pH level was measured using a pH meter. The fluoride concentration in the beverages ranged from 0.02±0.00 mg/L to 2.77±0.06 mg/L. Tea was found to have the highest fluoride concentration. The intake of fluoride from consumption of other types of beverages is below the lowest-observed-adverseeffect level (except tea). The pH of the beverages included in the study ranged from 2.20±0.01 to 7.76±0.00. Carbonated beverages (mean pH: 2.98±0.50) were found to be extremely acidic followed by fresh fruit juices (mean pH: 3.38±0.34) and fruit flavoured beverages (mean pH: 3.90±0.92). The correlation between fluoride and pH levels was weak, τ = 0.058 and not statistically significant (p

Electrochemical Measurement System for Chlorides in Drinking and Wastewater

This paper presents a system for the measurement of chlorides in drinking and wastewater, based on an electrochemical process using a selective electrode as a transducer, which was developed by this group. The measurement for the concentration is carried out by introducing the implemented electrode (considered as reference) in the sample that will be analyzed; then a current is passed producing a potential difference in the system. Different aqueous solutions of sodium chloride (NaCl) were used, ranging between 35 and 3546 µg of chloride ions (Cl−). As a data acquisition and monitoring system for the analysis, an ATmega 328P microcontroller was used as the main capture element for subsequent interpretation through graphics. The experimental results show that it was possible to detect a potential difference in the electrochemical measurement system that corresponded to 35 µg of chloride ions (Cl−), making clear the detection process and the selectivity of chloride ions. It is important to mention that with this measurement system and the applied methodology, results are obtained in real time using a small sample volume and without generate ng extra liquid waste, compared to the application of the traditional analytical titrimetric method. Finally, this chloride measurement system is inexpensive and can be used in drinking and wastewater measurements.

Synthesis of Zinc Fluoroborate by Wet Method and Its Application as a Flame Retardant for Cotton Fabrics

In this study, zinc fluoroborate was synthesized by wet method using fluoroboric acid and zinc oxide as reactant and its usability as flame retardant for cotton fabrics was investigated. The wet method is economical, green, efficient and applicable for a large-scale. The maximum yield was determined related to the variation of reactant ratio, temperature, reaction period and stirrer rate. The characterization of the product was carried out by means of FTIR, BF4- ion selective electrode and XRD. The maximum yield of 97% was achieved at the reactant mole ratio (nZnO/nHBF4) of 1:3, temperature of 90 °C and reaction period of 90 minutes. The purity of the synthesized product was found as 98 %. Flame retardancy and high temperature resistance effects of zinc fluoroborate on cotton fabrics were investigated by LOI test and high temperature durability test method, respectively. Although LOI value of the untreated original fabric was determined as 16, this value increased above 55 by impregnating of fabric with 50 % zinc fluoroborate solution.