Determination of cesium ions in environmental water samples with a magnetic multi-walled carbon nanotube imprinted potentiometric sensor

Determination of cesium using nickel hexacyanoferrate by stripping voltammetry

The determination of cesium ions (Cs+) is important for various applications, including resource utilization, environmental monitoring, and human health. Electrochemical sensors, with their inherent advantages, stand out as an ideal choice for Cs+ detection. However, electrode materials for Cs+ sensors usually face problems such as poor selectivity and complex synthesis. Herein, a method employing nickel hexacyanoferrate (NiHCF) as the electrode material for stripping voltammetry in the determination of Cs+ was proposed. Both adsorption and electrochemical intercalation exhibited selectivity. In the presence of interfering ions at a 10 : 1 molar ratio to Cs+, Cs+ was still preferentially intercalated in NiHCF. However, electrochemical intercalation exhibits superior selectivity for Cs+ compared to adsorption. Meanwhile, the effect of adsorption on the detection was minimized by electrochemical intercalation. Based on the standard addition method, Cs+ was determined using both adsorption and electrochemical intercalation methods. The error reduced significantly from 32.7% above the theoretical value through adsorption to 9.5% below the theoretical value through electrochemical intercalation. This approach not only enhanced the measurement accuracy but also reduced the costs associated with both measurement and preparation. The study proposed a cost-effective and rapid method for Cs+ measurement using Prussian blue analogs.

A simple dual responsive chemosensor for selective sensing of Cs+ for environmental monitoring and mimicking molecular logic gates

Detection of toxic metals is of vital importance to safeguard both public health and the ecosystem. Herein, we investigate the newly designed and synthesised isoxazole-based azo dye, (E)-cyclopentyl(5-((5-(4-fluorophenyl) isoxazole-3-yl) diazenyl)-2-hydroxyphenyl) methanone (FPAZ), as a dual chromogenic and fluorogenic sensor. FPAZ demonstrates high selectivity, reusability and ultra-sensitivity towards Cs+ ions manifested through naked eye detection in aqueous medium by employing simple and economic optical spectroscopy techniques. The color change from colourless to dark yellow and enhancement of fluorescence intensity reveal about FPAZ-Cs+ complexation by UV-Vis and fluorescence spectroscopy respectively. The complexation is also supported by DFT calculations. The LOD is estimated to be 0.476 µM, which by far, is the lowest LOD obtained for Cs+ detection. Further, FPAZ is fabricated with various flexible materials (paper, cotton, non-woven fabric) which provide information about on-site Cs+ ion contamination by means of change in relative RGB values using a handy smart-phone camera. Besides this, the logic gate as IMPLICATION and INHIBIT is designed employing Cs+ and Cl- ions as inputs and absorbance maxima as output. Overall, the developed chemosensor is simple, quick, and more promising than previously reported systems, as it does not need any chemical modification, expensive instruments, or expertise.

Ion-Selective Electrodes with Solid Contact Based on Composite Materials: A Review

Potentiometric sensors are the largest and most commonly used group of electrochemical sensors. Among them, ion-selective electrodes hold a prominent place. Since the end of the last century, their re-development has been observed, which is a consequence of the introduction of solid contact constructions, i.e., electrodes without an internal electrolyte solution. Research carried out in the field of potentiometric sensors primarily focuses on developing new variants of solid contact in order to obtain devices with better analytical parameters, and at the same time cheaper and easier to use, which has been made possible thanks to the achievements of material engineering. This paper presents an overview of new materials used as a solid contact in ion-selective electrodes over the past several years. These are primarily composite and hybrid materials that are a combination of carbon nanomaterials and polymers, as well as those obtained from carbon and polymer nanomaterials in combination with others, such as metal nanoparticles, metal oxides, ionic liquids and many others. Composite materials often have better mechanical, thermal, electrical, optical and chemical properties than the original components. With regard to their use in the construction of ion-selective electrodes, it is particularly important to increase the capacitance and surface area of the material, which makes them more effective in the process of charge transfer between the polymer membrane and the substrate material. This allows to obtain sensors with better analytical and operational parameters. Brief characteristics of electrodes with solid contact, their advantages and disadvantages, as well as research methods used to assess their parameters and analytical usefulness were presented. The work was divided into chapters according to the type of composite material, while the data in the table were arranged according to the type of ion. Selected basic analytical parameters of the obtained electrodes have been collected and summarized in order to better illustrate and compare the achievements that have been described till now in this field of analytical chemistry, which is potentiometry. This comprehensive review is a compendium of knowledge in the research area of functional composite materials and state-of-the-art SC-ISE construction technologies.

226Ra and 137Cs determination by inductively coupled plasma mass spectrometry: state of the art and perspectives including sample pretreatment and separation steps

Achieving precise and accurate quantification of radium (²²⁶Ra) and cesium (¹³⁷Cs) by inductively coupled plasma mass spectrometry (ICP-MS) is of particular interest in the field of radiological monitoring and more widely in environmental and biological sciences. However, the accuracy and sensitivity of the quantification depend on the analytical strategy implemented. Eliminating interferences during the sample handling step and/or during the analysis step is critical since presence of matrix elements can lead to spectral and non-spectral interferences in ICP-MS. Consequently, before the ICP-MS analysis, multiple sample preparation approaches have been applied to purify and/or pre-concentrate environmental and biological samples containing radium and cesium through years, such as (co)-precipitation, solid phase extraction (SPE) or dispersive SPE (dSPE). Separation steps using liquid chromatography and capillary electrophoresis can also be useful in complement with the abovementioned sample preparation techniques. The most attractive sample handling technique remains SPE but efficiency of the extraction procedures is currently limited by sorbent specificity. Indeed, with the recent advances in ICP-MS instrumentation, it becomes indispensable to eliminate residual interferences and improve sensitivity. It is in this direction that it will be possible to meet analytical challenges, e.g. analyzing radium and cesium at concentrations below the pg L^-1 range in complex matrices of small volumes, as they are found for instance in pore waters or in biological samples. Development of new innovative sorbents based for example on hybrid and nanostructured materials has been reported with the aim of enhancing sorbent specificity and/or capacity. In the present review, the performances of the different analytical approaches are discussed, followed by an overview of applications.

Tuning the sumanene receptor structure towards the development of potentiometric sensors

Herein, we report for the first time the application of a sumanene derivative in potentiometric recognition of caesium cations. The structure of the sumanene receptor was carefully tuned to obtain its compatibility with polyvinyl chloride plasticized membranes of potentiometric sensors. The developed ion-selective electrodes based on membranes doped with octyloxybenzene sumanene exhibited a near theoretical sensitivity towards caesium cations, with a detection limit of 4 μM Cs⁺.