A Solid-Contact Reference Electrode Based on Silver/Silver Organic Insoluble Salt for Potentiometric Ion Sensing
Ontology highlight
ABSTRACT:
SUBMITTER: Gan S
PROVIDER: S-EPMC9886000 | biostudies-literature | 2022 Aug
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Current solid potentiometric ion sensors mostly rely on polymeric-membrane-based, solid-contact, ion-selective electrodes (SC-ISEs). However, anion sensing has been a challenge with respect to cations due to the rareness of anion ionophores. Classic metal/metal insoluble salt electrodes (such as Ag/AgCl) without an ion-selective membrane (ISM) offer an alternative. In this work, we first compared the two types of SC-ISEs of Cl- with/without the ISM. It is found that the ISM-free Ag/AgCl electrode discloses a comparable selectivity regarding organic chloride ionophores. Additionally, the electrode exhibits better comprehensive performances (stability, reproducibility, and anti-interference ability) than the ISM-based SC-ISE. In addition to Cl-, other Ag/AgX electrodes also work toward single and multi-valent anions sensing. Finally, a flexible Cl- sensor was fabricated for on-body monitoring the concentration of sweat Cl- to illustrate a proof-of-concept application in wearable anion sensors. This work re-emphasizes the ISM-free SC-ISEs for solid anion sensing.
| S-EPMC8707216 | biostudies-literature
Project description:A new solid-contact potentiometric ion-selective electrode for the determination of SCN- (SCN-ISE) has been described. Synthesized phosphonium derivative of calix[4]arene was used as a charged ionophore. The research included selection of the ion-selective membrane composition, determination of the ISEs metrological parameters and SCN-ISE application for thiocyanate determination in human saliva. Preparation of the ISEs included selection of a plasticizer for the ion-selective membrane composition and type of the electrode material. The study was carried out using ISE with liquid internal electrolyte (LE-ISE) and solid-contact electrodes made of glassy carbon (GC-ISE) and gold rods (Au-ISE). The best parameters were found for GC sensors for which the ion-selective membrane contained chloroparaffin as a plasticizer (S = 59.9 mV/dec, LOD = 1.6 ´ 10-6 M). The study of potentiometric selectivity coefficients has shown that the thiocyanate-selective sensor could be applied in biomedical research for determination of SCN- concentration in human saliva. The accuracy of the SCN- determination was verified by testing 59 samples of volunteers' saliva by potentiometric sensors and UV-Vis spectrophotometry as a reference technique. Moreover, SCN- concentrations in the smokers' and non-smokers' saliva were compared. In order to investigate the influence of various factors (sex, health status, taken medications) on the thiocyanate level in the saliva, more extensive studies on a group of 100 volunteers were carried out. Additionally, for a group of 18 volunteers, individual profiles of SCN- concentration in saliva measured on a daily basis for over a month were collected.
| S-EPMC7288078 | biostudies-literature
Project description:Determination of phosphate ions in aqueous solutions attracts a great deal of interest in the areas of environment, medicine, and agriculture. As phosphoric acid is a poly basic acid, the different forms of existence at different pH result in direct determination facing a big challenge. Herein, we reported a potentiometric phosphate ion sensor based on a surface-modified tungsten electrode. Pure tungsten was electrodeposited at a constant potential of 0.2 V versus Ag|AgCl in Na2HPO4. WO3 and H3O40PW12·xH2O were electrodeposited on the surface of the tungsten electrode. The modified tungsten electrode was used as a working electrode in a two-electrode system to detect the concentration of phosphate ions in aqueous solutions. The detection limit of the modified tungsten electrode for phosphate ions is 10-6 M from pH 7 to pH 8 and 10-5 M from pH 9 to pH 10. It has good selectivity to other common anions. The long-term monitoring experiment showed that the potential fluctuation was less than ±3 mV in 24 h. Compared to conventional determination methods, the current phosphate ion sensor showed a close value in a real sample. The mechanism of phosphate ion response was investigated in detail. This sensor possesses advantages of simple manufacture, low cost, a wide pH range for detecting, and good selectivity.
| S-EPMC8173557 | biostudies-literature
Project description:The solid contact ion-selective electrode (ISE) is a promising skin-interfaced monitoring system for sweat ions. Despite a growing number of on-body usages of ISE with fancy new materials and device fabrications, there are very few reports attempting to validate ISE results with a gold standard technique. For this purpose, this work uses inductively coupled plasma-optical emission spectrometry (ICP-OES) as a reference technique to conduct a direct evaluation of the sweat sodium and potassium ion levels obtained by ISE in an off-body approach. Eight healthy male subjects were recruited to collect exercise-induced sweat. It was found that sweat sodium and potassium ions present a rather wide concentration range. The sweat sodium concentration did not vary greatly in an exercise period of half an hour, while the sweat potassium concentration typically decreased with exercise. Mineral drink intake had no clear impact on the sweat sodium level, but increased the sweat potassium level. A paired t-test and mean absolute relative difference (MARD) analysis, a method typically used for evaluating the performance of glucometers, was employed to compare the results of ISE and ICP-OES. The statistical analysis validated the feasibility of ISE for measuring sweat ions, although better accuracy is required. Our data suggests that overweight subjects are likely to possess a higher sweat sodium level.
| S-EPMC9026306 | biostudies-literature
Project description:A beryllium(II)-ion-selective poly(ethylenedioxythiophene) (PEDOT) solid contact electrode comprising 9,10-dinitrobenzo-9-crown-3-ether was successfully developed. The all-solid-state contact electrode, with an oxygen-containing cation-sensing membrane combined with an electropolymerized PEDOT layer, exhibited the best response characteristics. The performance of the constructed electrode was evaluated and optimized using potentiometry, conductance measurements, constant-current chronopotentiometry, and electrochemical impedance spectroscopy (EIS). Under optimized conditions, which were found for an ion-selective membrane (ISM) composition of 3% ionophore, 30% polyvinylchloride (PVC), 64% o-nitro phenyl octyl ether (o-NPOE), and 3% sodium tetraphenylborate (NaTPB), the fabricated electrode exhibited a good performance over a wide concentration range (10-2.5-10-7.0 M) and a wide pH range of 2.0-9.0, with a Nernstian slope of 29.5 mV/D for the beryllium (II) ion and a detection limit as low as 10-7.0 M. The developed electrode shows good selectivity for the beryllium(II) ion over alkali, alkaline earth, transition, and heavy metal ions.
| S-EPMC7664937 | biostudies-literature
Project description:We introduce fluoride-selective anion exchange resin sorbents as sensitisers into membranes for water-gated field effect transistors (WGTFTs). Sorbents were prepared via metal (La or Al)-loading of a commercial macroporous aminophosphonic acid resin, PurometTM MTS9501, and were filled into a plasticised poly(vinyl chloride) (PVC) phase transfer membrane. We found a potentiometric response (membrane potential leading to WGTFT threshold shift) to fluoride following a Langmuir-Freundlich (LF) adsorption isotherm with saturated membrane potential up to ~480 mV, extremely low characteristic concentration c1/2 = 1/K, and picomolar limit of detection (LoD), even though ion exchange did not build up charge on the resin. La-loading gave a superior response compared to Al-loading. Membrane potential characteristics were distinctly different from charge accumulating sensitisers (e.g., organic macrocycles) but similar to the Cs+ (cation) selective ion-exchanging zeolite mineral 'mordenite'. We propose a mechanism for the observed threshold shift and investigate interference from co-solutes. Strong interference from carbonate was brought under control by 'diluting' metal loading in the resin. This work sets a template for future studies using an entirely new 'family' of sensitisers in applications where very low limit of detection is essential such as for ions of arsenic, mercury, copper, palladium, and gold.
| S-EPMC7601498 | biostudies-literature
Project description: Not available
| S-EPMC10905735 | biostudies-literature
Project description:Solid-contact ion-selective electrodes (ISEs) have the inherent advantage of being miniaturized in addition to maintaining high selectivity and sensitivity of the ionophore-based ISE. The major disadvantage of ISEs is the necessity of performing a calibration curve (varying the intercept in the linear calibration curve equation) each time before running experiments, which limits their application as one-time disposable sensors or for use in remote water sample analysis. To overcome these challenges, we designed a unique back contact made of 3,4-ethylenedioxythiophene (EDOT) and 4-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl-methoxy)-1-butanesulfonic acid, sodium salt (EDOT-S). The calibration-free ISEs showed near Nernstian responses of 57.2 ± 0.2 mV/log [K+] and 28.5 ± 0.3 mV/log [Ca2+], while maintaining their respective selectivity against major interfering ions. The detection limits for Ca2+ and K+ ISEs were 0.45 ± 0.01 and 1.68 ± 0.18 μM, respectively. The charging cycles of the PEDOT: PEDOT-S back contact allowed us to fix the background potential at a desired fixed intercept value across different ionophores (K+, Ca2+). This protocol was used to determine the K+ and Ca2+ contents in creek water samples. The activity and concentration of [Ca2+] and [K+] in a local creek was found to be 257 ± 7.3 and 28.1 ± 1.1 μM, respectively.
| S-EPMC9213238 | biostudies-literature
Project description:For potentiometric sensing of barbital (BAR), unique micro-sized imprinted polymer/multiwalled carbon nanotube (MWCNT)-based sensors are introduced. MWCNT is a lipophilic ion-to-electron transducing substance. A synthetic, described, and integrated barbital sodium molecular imprinted polymer (MIP) was used as a recognition receptor for potentiometric transduction in a plasticized polyvinyl chloride membrane. Methacrylic acid and ethylene glycol dimethacrylic acid are used as the functional monomer and crosslinking agent, respectively, in the synthesis of the MIPs. In the operating concentration range of 1.0 × 10-3 to 2.0 × 10-7 M, the sensors' Nernstian slope was -56.8 ± 0.9 mV/decade, with a detection limit of 1.0 × 10-7 M. The sensor displayed an accurate response time of 10 s and consistent potential response in the pH range of 8.5-11. Using chronopotentiometry tests, the interfacial capacitance of the presented ion-to-electron transducer was assessed. When compared to sensors without MWCNTs, the interfacial double-layer capacitance for sensors based on those layers reached 52.5 μF. After the addition of the MWCNTs nanocomposite layer, the water layer was eliminated between the sensing membrane and the conducting substrate. A wide range of applications for the proposed sensors for BAR detection in real samples can be provided by the sensors' strong selectivity over the interfering species. The suggested sensors were successfully used to determine BAR in urine samples that had been spiked.
| S-EPMC9494433 | biostudies-literature
Project description:This work reports the design, synthesis, and characterization of a novel redox-active conjugated polyaniline containing quinone moiety as a solid state reference electrode. The union of electro-active quinone with π-conjugated polyaniline was created by the first chemical synthesis of para-dimethoxybenzene-functionalized aniline as a monomer using a palladium-mediated coupling. The successful polymerization of the as-prepared monomer was accomplished without acid additives. Its post-polymerization modification with strong Lewis acid boron tribromide furnished unique poly (aniline quinone/hydroquinone) with desired properties for all-solid-state reference electrode (RE) applications. The electrochemical responses from the conjugated polyaniline backbone in this unique polymer have been "suppressed" by the quinone pendant. The resulting poly (aniline quinone) showed a quasi-reversible redox process from the redox behavior of the pendant quinone. The stable electrode potential of this poly (aniline quinone/hydroquinone) suggested that it was a single phase in which the amounts of totally reduced and totally oxidized species could be maintained at a constant in various solvents and electrolytes. Its electrochemical stability was excellent with 95% peak current retention after continuous cyclic voltammetric testing. The aniline and quinone moieties in poly (aniline quinone/hydroquinone) render it to have both hydrophilic and hydrophobic compatibility. It showed excellent behavior as a reference electrode in aqueous and non-aqueous media and can be used in both non-zero current and zero-current conditions, providing a stable potential with a maximum potential drift of ~4.7 mV over ten consecutive days.
| S-EPMC6290589 | biostudies-literature