Analytical & Bioanalytical Electrochemistry
Volume:15 Issue: 1, Jan 2023

This study aimed at developing a voltammetry-based method sensitive to interferences. Phosphate ion when reacted with molybdate forms an electroactive phosphomolybdate complex. Differential Normal Pulse Voltammetry (DNPV) and Cyclic Voltammetry (CV) techniques were used to assess the complex. Analysis by CV gave two redox centres with redox potentials of 0.167±0.02 V and 0.357±0.02 V, diffusion coefficients (D) of 1.408×10-4 cm2 s-1 and 5.629×10-7 cm2 s-1. Analysis by DNPV also gave two responses with potentials of 0.02±0.001 V and 0.33±0.001 V. DNPV response increased with phosphate concentration. The Linear Concentration Range (LCR) was found to be 0 to 8 mg/L, Limit of Detection (LOD) of 0.06586 mg/L, Limit of Quantitation (LOQ) of 0.21952 mg/L. The method had an accuracy range of 89%-102% and a precision of 7.93%. The method was evaluated using fifty water samples randomly collected from Lake Naivasha, Kenya. The mean phosphate concentration was 0.6156±0.1046 mg/L (at 95% Confidence Level). The study, therefore, showed that the DNPV method developed could be applied to the determination of phosphates in water at low levels.

Using the decoction extraction method, we obtained twice crude aqueous extracts of Artemisia absinthium or (wormwood) that was made to start a comparative study, between the first extract which corresponds to the leaves of our plant (AQL) and the second which belongs to the stems (AQS). The inhibitory activity of the twice extracts of Artemisia absinthium was studied by weight loss, potentiodynamic polarization and electrochemistry impedance spectroscopy. The morphology of the mild steel surface was examined by SEM.The inhibitory efficiency increased with the increase of the concentration, we reach an efficiency of 85% for AQL and 82% for AQS at 303 K for a concentration of 0.2 g/ L. Two Artemisia absinthium extracts used to prevent corrosion in mild steel adhere to the Langmuir adsorption isotherm during adsorption. The majority compound is 3,4-dihydroxybenzoic acid in the case of extracts with percentages of 42.4% for AQL and 42.2% for AQS. The DFT results of the majority compounds allowed us to have an idea on the power of adsorption of these last ones on the surface of the metal, indeed there can be a combined effect of the various molecules constituting the extracts on the corrosion inhibition.

A potentiometric response of an ion-selective electrode with a new ionophore 8,11,14-triaza-1,4-dioxo-5(6),16(17)-ditolylcycloseptadecane (TADODTSD) toward Cr(III) ions was studied. The designed electrode showed a Nernstian behavior with a slope of 19.6±0.5mV/decade in a working concentration range of 1.0×10-8-1.0×10-1 mol L-1 and a detection limit of 8.0×10-8 mol L-1. A membrane composition made of PVC: DBP: ionophore (TADODTSD): NaTPB; 30%: 60%: 8%: 2 wt.% displays the best results. Response time was found to be 7 seconds and can be used for 120 days without showing any substantial deviation in potential. The proposed electrode exhibits selectivity for Cr(III) ions. The electrode worked well under laboratory conditions with its, potential response being constant over a pH range of 3.0-8.0. The electrode proposed in this work could be used to determine the presence of Cr(III) ion in wastewater and also an indicator electrode with EDTA.

A poly(vinyl chloride) membrane sensor for barium was prepared using 4ʹ,4ʺ(5ʺ)-Di-tert-butyldibenzo-18-crown-6 (DTB 18C6) as an ion carrier. The optimized membrane with PVC:DOP:DTB18C6:KTCPB percent ratio of 33:60:5:2 led to a Nernstian calibration slope of 25.23 mV per decade, from 1×10-7 to 1×10-1 M . Dioctyl phthalate was found to act as the best plasticizer in terms of controlling the response and durability of the sensor the lifetime of the fabricated sensor. The sensor had a short response time of 18 s and its response was independent from pH from 2.0 to 12.4 working pH ranges. The selectivity behavior of the sensor for barium in the presence of alkali, alkaline earth, transition and heavy metal ions was very good. The applicability of the sensor was evaluated through using it as an indicator in the potentiometric titration of SO42- ions.

Due to their effect on human health, rapid, sensitive, and accurate methods for detecting foodborne bacterial pathogens are becoming increasingly important. There are more than 250 types of bacterial foodborne disease, including more than 90% of outbreaks of foodborne illness worldwide, which is considered to be one of the greatest threats to public health.  Among the diagnostic methods, electrochemical biosensors have features that make them very efficient in designing and manufacturing biosensors. Potentiometric biosensors have been recognized for their effectiveness in detecting analytes with low cost, ease of use, and simple instrumentation. This article reviews key advances in potentiometric biosensors of foodborne bacterial pathogens. The categorization of different potentiometric biosensors is done on the basis of various foodborne bacterial pathogens involving Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Salmonella typhimurium.

Gadolinium is a rare earth element with various applications, which has led to the distribution of water-soluble compounds of this element and has subsequently, increased the chances of exposure of humans and animals to Gd3+. Given the effects this can have on human and animal health the analysis of gadolinium compounds has become more important and ion-selective electrodes constitute a set of versatile tools for this purpose. The manuscript tends to provide an overview on the elective polymeric membrane electrodes for the analysis of Gd3+ and their performance.