Plasticized Poly Vinyl Chloride Membrane Research Articles

Revolutionizing sensing technologies: Crafting a green, ultra-sensitive bismuth optical sensor via fixation of 5-(2′,4′-dimethyl-phenylazo)-6-hydroxypyrimidine-2,4-dione on PVC membrane

An innovative and exceptionally responsive optical sensing device engineered to selectively identify Bi(III) ions in water-based solutions. The sensing component, 5-(2′,4′-dimethylphenylazo)-6-hydroxypyrimidine-2,4-dione (DMPAHPD), is incorporated into a plasticized polyvinyl chloride (PVC) membrane. The sensor demonstrates an exceptional selectivity for Bi(III) within a broad dynamic range spanning from 7.5 × 10−10 to 4.2 × 10−5 M at pH 2.25. Notably, it achieves lower quantification and detection limits of 7.25 × 10−10 and 2.15 × 10−10 M, respectively. The optode membrane’s response to Bi(III) proves to be entirely reversible, demonstrating remarkable selectivity for Bi(III) ions over a diverse range of other cations and anions. The sensor exhibits favorable performance characteristics, including good reversibility, a wide dynamic range, a prolonged lifespan, sustained response stability over the long term, and high reproducibility. This visual chemical sensor exhibits potential for real-world usage, offering consistent outcomes when assessing Bi(III) levels in matrices such as water, soil, plants, biological and synthetic mixtures. Importantly, the sensor’s performance is comparable to corresponding data achieved from inductively coupled plasma atomic emission spectroscopy (ICP-AES).

Real-Time Potentiometric Monitoring of Tetrachloroaurate(III) with an Ion-Selective Electrode and Its Applications to HAuCl4 Iodide-Catalyzed Reduction by Hydroxylamine

Ion-selective electrodes for tetrachloroaurate(III) have been developed for potentiometric monitoring of the reduction reaction of tetrachloroaurate(III). Three different plasticized polyvinyl chloride membranes containing tridodecymethylammonium chloride as an anion exchanger were investigated. These membranes differ in the plasticizer used, either 2-nitrophenyl octyl ether (NPOE) or tricresyl phosphate (TCP) or bis-(2-ethylhexyl) sebacate (DOS). The potentiometric response of the electrodes to the tetrachloroaurate(III) concentration was studied by two methods. In the first method, commonly used in the calibration of ion-selective electrodes, successive tetrachloroaurate(III) concentration increments were used and the potential was allowed to stabilize after each concentration step. The second method was developed to mimic the tetrachloroaurate(III) reduction reaction in which there is a continuous decrease in the concentration of tetrachloroaurate(III). This was achieved by continuously diluting an initial concentration of tetrachloroaurate(III) by pumping a diluent solution while keeping the sample volume constant. This method gave an excellent linear response to the tetrachloroaurate(III) concentration. The calibrated electrodes were used for the potentiometric monitoring of the kinetics of a newly observed reaction: the reduction of tetrachloroaurate(III) by hydroxylamine catalyzed by iodide. A mechanism for this reaction is proposed on the basis of the experimental results obtained.

Ion-Selective Membrane Electrode for Determination of the Octahydrotriborate Anion

An ion-selective electrode (ISE) based on a plasticized polyvinyl chloride membrane chemically doped with tetradecylammonium octahydrotriborate ([(С10H21)4N+]) has been developed. It is shown that the electrode has a reversible potentiometric response with respect to the octahydrotriborate anion in the presence of a number of other inorganic anions. The influence of the concentration of the electrode-active material and the nature of the plasticizer in the membrane phase on the electrochemical characteristics of the fabricated sensor have been studied. The optimal composition of the ion-sensitive membrane has been found. It has been found that the developed sensor provides a wide range of detectable concentrations of(1 × 10–7…1 × 10–2) and a low detection limit (10–7.3 M). The new ISE can be recommended for direct potentiometric detection of free octahydrotriborate anions in technological aqueous solutions.

Molecularly Imprinted Polymer Modified with an MWCNT Nanocomposite for the Fabrication of a Barbital Solid-Contact Ion-Selective Electrode.

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.

Транспортные свойства немодифицированных и модифицированных нанотрубками полианилина амоксициллинселективных мембран

The transport processes occurring in polymer matrix characterize their physico-chemical properties, determine the directions of practical application. The literature data on ion transport in plasticized polymer membranes and theoretical aspects of membrane transport are critically reviewed. The effect of the modifier on the transport properties of membranes is shown. The article shows the possibility of implementing a new amoxicillin-selective plasticized membrane ([Ag(Amox)2]DMDSA), which includes a molecular imprinted polymer (MIP) – polyaniline nanotubes (PANI NT), which are of particular interest as modifiers of sensory and membrane compositions. The transport properties of unmodified and modified polyaniline nanotubes of plasticized polyvinyl chloride membranes have been studied. The effect of the concentration of near-membrane aqueous solutions of antibiotics, modifier on transport properties has been established. Quantitative characteristics of membrane transport are estimated: permeability coefficient and ion flux.

Determination of levamisole using ion-selective electrode

Current development of applied ionometry requires focusing of theoretical studies both on revealing the nature of the selectivity of electrode membranes and on the developing the new methods of membrane synthesis and their modification with the goal of obtaining more perfect structural units with improved functional properties. Elucidation of the relationship between the structural characteristics of the membranes and their effect on the electro-analytical properties is a rather important task. The interaction of organic cation levamisole with bromophenol blue was studied to meet the goals. Levamisole-selective sensor with a plasticized polyvinyl chloride (PVC) membrane has been developed. The electrode contains an ionic associate of levamisole with bromophenol blue. PVC was used as a matrix to model the membrane composition. Membranes plasticized with dibutyl phthalate (DBP), diethyl phthalate (DEP), dioctyl phthalate (DOP), dinonyl phthalate (DNP), dibutyl sebacate (DBP), tricresyl phosphate (TCP) were studied. It was shown that the nature of the plasticizer insignificantly affected the analytical characteristics of the electrode. The response is linear within the concentration range of 1 × 10–5 – 1 ×10–1 mole/liter with the slope of the electrode function 52.1 ± 1.0 mV/pC. The sensor has a quick response (10 sec) and can be used for at least 8 weeks without any divergence in the long run. The operation life of the membranes with a high plasticizer content is much longer. The electrode can be used within pH range of 3.0 – 8.0. Potentiometric selectivity coefficients of the electrode relative to a number of potentially interfering ions were determined. The developed electrode was tested in determination of levamisole in model solutions and pharmaceuticals («Decaris» and «Levamisole-Zdorovye»).

Molecularly Imprinted Polymer Based GCE for Ultra-sensitive Voltammetric and Potentiometric Bio Sensing of Topiramate.

Topiramate (TOP) drug is classified as one of the most commonly used human drugs for anticonvulsants and antiepileptic, so its rapid detection and monitoring is of great importance. In this work, new potentiometric (MIP/PVC/GCE) and voltammetric (MIP/GO/GCE) sensors for the selective and sensitive determination of TOP were fabricated based on the molecularly imprinted polymer (MIP) approach. The MIP was synthesized by the polymerization of acrylamide and methacrylic acid as monomers, in the presence of TOP as a template and ethylene glycol dimethacrylate as a cross-linker. The obtained products were characterized by FT-IR, SEM, BET, and EDX. The MIP was embedded in a plasticized polyvinyl chloride membrane and used as a potentiometric sensor for sensing TOP. Alternatively, the synthesized MIP and graphene oxide (GO) were deposited layer-by-layer on the surface of GCE to construct a voltammetric sensor for studying the electrochemical behavior of the drug. Under optimized conditions, both electrochemical sensors showed excellent linear relationships between the concentration of TOP and the response signals of MIP/GO/GCE or MIP/PVC/GCE sensors in the 2.7 × 10-10 to 4.9 × 10-3 M and 1 × 10-9 to 3.4 × 10-3 M ranges, respectively. Also, both sensors have good reproducibility and high stability for up to 15 days for a voltammetric sensor and 28 days for a potentiometric sensor. The utility of these sensors was checked for TOP analysis in different real samples with good recovery (92.8 - 99%).

Plasticized PVC Membrane Modified Electrodes: Voltammetry of Highly Hydrophobic Compounds.

In the last 50 years, plasticized polyvinyl chloride (PVC) membranes have gained unique importance in chemical sensor development. Originally, these membranes separated two solutions in conventional ion-selective electrodes. Later, the same membranes were applied over a variety of supporting electrodes and used in both potentiometric and voltammetric measurements of ions and electrically charged molecules. The focus of this paper is to demonstrate the utility of the plasticized PVC membrane modified working electrode for the voltammetric measurement of highly lipophilic molecules. The plasticized PVC membrane prevents electrode fouling, extends the detection limit of the voltammetric methods to sub-micromolar concentrations, and minimizes interference by electrochemically active hydrophilic analytes.

Reparability of aged PVC waterproofing membranes: Effect of joining method

Plasticized poly vinyl chloride (PVC) membranes are widely used for waterproofing in civil engineering works. Such membranes are susceptible to environmental degradation and accidental damage, and may thus require localized repairs throughout their service life. These operations typically involve covering the damaged areas with new PVC membranes, prompting the need to execute joints between new and aged membranes. This paper presents an experimental assessment of the performance of two methods used for such repairs, namely hot air welding and solvent-based adhesive bonding. Plasticized PVC membranes with glass-fibre reinforcement were aged by heat weathering for up to 24 weeks in a temperature controlled chamber at 70 °C. The aged membranes were then bonded to new (unaged) membranes and subjected to shear and peel tests, while individual membranes were also tested in tension. The tensile and shear results are in agreement with experimental observations found in other studies regarding the effects of heat ageing on the tensile and shear behaviour of PVC membranes and their seams; moreover, the shear tests suggest that damage is introduced in the membranes during heat welding, resulting in reduced deformation capacity after the execution of the welds. The results of peel tests show that the overall performance of solvent-based adhesive joints is significantly better than that of hot air welded joints. Furthermore, following the heat ageing programme, even though the PVC membranes exhibited reduced elongation at break, this did not significantly hinder the effectiveness of solvent-based adhesive joints; conversely, the hot air welded joints exhibited reductions in average peeling force of up to 60% after 24 weeks of heat ageing.

Sensors Based on Single- and Double-Layer Plasticized Membranes for the Potentiometric Determination of Mefenamic and Phenylanthranylic Acids

Sensors for the potentiometric determination of mefenamic and phenylanthranylic acids are prepared on the basis of single- and the double-layer plasticized polyvinylchloride membranes. Ion pairs of perchlorate and mefenamic and phenylanthranylic acid with basic fuchsin are synthesized for the fabrication of membranes. The composition of compounds is confirmed by spectrophotometry and IR spectrometry. Effects of different factors on the electrode characteristics are studied, the composition of the membranes is optimized. The proposed procedure for the fabrication of double-layer membranes ensures the improvement of the properties of sensors for mefenamic and phenylanthranylic acids. The developed procedures are applied to the analysis of pharmaceutical preparations.

Potentiometric Sensor for Benzylpenicillin Determination

A potentiometric benzylpenicillin-sensitive sensor with a plasticized polyvinyl-chloride membrane was developed. The sensor contains a benzylpenicillin—rhodamine 6G ion pair. The response is linear for benzylpenicillin concentrations in the range 10–3 – 10–1M with an electrode-function slope characteristic of singly charged anions and a minimum detected concentration of (6.3 – 7.9) × 10–4 M. This sensor could be used to detect and determine benzylpenicillin in pharmaceuticals.

An integrated ion-selective optode sensor cartridge for directly detecting electrolyte ions in blood plasma without pretreatment to adjust pH

We present a new integrated optode sensor cartridge that directly detects potassium, sodium, and chloride ions in blood plasma without pretreatment to adjust pH. Each optode sensor mainly consists of two separate layers, the optode and a dried buffer, which work by introducing plasma without blood cells filtered by a membrane filter. The optode layer uses a neutral ion-selective optode that is composed of an ionophore, a pH indicator dye (chromoionophore), and ionic additives incorporated in a plasticized polyvinyl chloride membrane. The dried buffer layer, which dissolves on contact with plasma, is applied to the optode layer, resulting in the constant pH of the plasma within the optode membrane. We determined the pHs of each dried buffer (potassium, sodium, and chloride) layer to be 7.0, 6.0, and 4.5, respectively, based on the pKa of their corresponding chromoionophores and effective buffer ranges. Consequently, the sensor responses varied as a function of the potassium, sodium, and chloride ion concentrations. To validate the accuracy of the ion-selective optode sensors, we investigated the correlations of potassium, sodium, and chloride ion concentrations with a commercial system (cobas® 8000) and observed comparable agreement between the two systems with correlation coefficients of 0.976, 0.955, and 0.966, respectively.

Solid-Contact Ion-Selective Electrodes with Copper Hexacyanoferrate in the Transducer Layer

The possibility of using mixed Fe2+/Fe3+ copper hexacyanoferrate (CuHCF) as the material for the transducer layer of solid-contact ion-selective electrodes (SC-ISEs) with plasticized polyvinylchloride membranes is studied. The study is performed for K+-SC-ISEs and water-hardness SC-ISEs. It is shown that CuHCF combines the ion-exchange and redox properties and, hence, in principle, should be suitable for SC-ISEs. However, the reproducibility of SC-ISE potentials from one electrode to another and their stability in time are far below those of conventional ISEs with internal aqueous solution. The potentials of individual SC-ISEs can be brought closer to one another by their polarization using a potentiostat or by their short-circuiting to a saturated silver-chloride reference electrode.

Determination of paralytic shellfish toxins using potentiometric electronic tongue

Paralytic shellfish toxins (PSTs) are monitored in commercial bivalves in several countries in the world due to their toxicity to human consumers. The present work examines the application of an electronic tongue based on potentiometric chemical sensors to the quantification of PSTs in mussel extracts. The electronic tongue comprised six miniaturized sensors with solid inner contact and plasticized polyvinylchloride membranes. Calibration models were calculated by PLS regression using measurements in sixteen model mixed solutions containing four PSTs commonly found in bivalves from the Portuguese coast. Transfer of the calibration models to sample matrix was done by joint-PLS regression using measurements in five mussel extracts spiked with PST standards. Quantification of PSTs in extracts of naturally contaminated mussels, using the electronic tongue and updated calibration model, was in agreement with values of the chromatographic reference method. Those sensors alone or combined in an electronic tongue are useful tools for rapid screening of PST in bivalves.

Potentiometric chemical sensors for the detection of paralytic shellfish toxins

Potentiometric chemical sensors for the detection of paralytic shellfish toxins have been developed. Four toxins typically encountered in Portuguese waters, namely saxitoxin, decarbamoyl saxitoxin, gonyautoxin GTX5 and C1&C2, were selected for the study. A series of miniaturized sensors with solid inner contact and plasticized polyvinylchloride membranes containing ionophores, nine compositions in total, were prepared and their characteristics evaluated. Sensors displayed cross-sensitivity to four studied toxins, i.e. response to several toxins together with low selectivity. High selectivity towards paralytic shellfish toxins was observed in the presence of inorganic cations with selectivity coefficients ranging from 0.04 to 0.001 for Na+ and K+ and 3.6*10−4 to 3.4*10−5 for Ca2+. Detection limits were in the range from 0.25 to 0.9 μmolL−1 for saxitoxin and decarbamoyl saxitoxin, and from 0.08 to 1.8 μmolL−1 for GTX5 and C1&C2, which allows toxin detection at the concentration levels corresponding to the legal limits. Characteristics of the developed sensors allow their use in the electronic tongue multisensor system for simultaneous quantification of paralytic shellfish toxins.

Automatic potentiometric system for quantification of three imidazole derivatives based on new polymeric PVC membrane sensors

New potentiometric monitoring devices for trace and fast determination of three imidazole derivatives were presented. The sensing materials were fabricated by the inclusion of imidazolinium phosphomolybdate (Imd/PMA) (sensor I), imidazolinium tetraphenylborate (Imd/TPB) (sensor II), or dibenzo-24-crown-8 (DB24C8) (sensor III) in the plasticized polyvinyl chloride (PVC) matrix. The sensors showed clear enhanced response towards imidazolium [Imd+] ions over the concentration range 4.0 × 10−6–1 × 10−2 mol L−1 at pH 5 with 0.42 μg mL−1 as a detection limit. The selectivity was tested with various inorganic and nitrogenous organic ions. Long life span, fast response, long-term stability, and high reproducibility are shown for the sensors. Method validation for the proposed method was achieved by quantifying the detection limit, linear range, accuracy, precision, repeatability, and between-day variability. It revealed good performance characteristics of the proposed sensors. The applicability of the sensors for analyzing imidazole in urine samples was successfully demonstrated via recovery studies.

Phenoxy-substituted boron subphthalocyanine as a ionophore of ion-selective electrodes

Phenoxy-substituted boron subphthalocyanine was synthesized and studied as an ionophore of plasticized polyvinyl chloride membranes of ion-selective electrodes. The electrodes exhibit reversible response to dobutamine, demonstrating the cation function, as well as reversible response to the salicylate anion. The effects of concentration of the ionophore (0.2–5 wt %) and ionic components (sodium tetraphenylborate, TPhBNa, and tributylhexadecylphosphonium bromide, TBGDPBr), including ionic liquids (ILs), such as diphenylbutylethylphosphonium bis(triflyl)imide, diphenylbutylethylphosphonium hexafluorophosphate, and 1,3-dihexadecylimidazolium chloride, as well as plasticizers, such as ortho-nitrophenyloctyl ether and diethyl sebacate, on the electrochemical characteristics of membranes were studied. For the electrode containing 2% of the phenoxy-substituted boron subphthalocyanine in dobutamine and salicylate solutions, the slopes of the electrode function were 36 ± 1 mV/dec and–46 ± 3 mV/dec and the limits of detection (LODs) were 4 × 10–5 M and 3 × 10–4 M, respectively. The addition of an ionic liquid containing the diphenylbutylethylphosphonium cation and the bis(triflyl)imide and hexaflurophosphate anions to the membrane composition had no effect on the response of membrane electrodes to both dobutamine and salicylate. The use of phenoxy-substituted boron subphthalocyanine in an amount of 2% and the TPhBNa additive significantly improved sensor characteristics: the slope of the electrode function (S) for the dobutamine-selective electrode was (54 ± 1) mV/dec and LOD was 1 × 10–5 M. Dobutamine can be determined in the presence of dopamine, adrenalin, and glucose. Electrodes based on 2% phenoxy-substituted boron subphthalocyanine and 0.5% (C16H33)2ImCl, or TBGDPBr in salicylate solutions demonstrate the slope of the electrode function close to the theoretical one and a low limit of detection: S = (–59 ± 1) mV/dec, LOD = 2 × 10–5 M and S = (–57 ± 1) mV/dec, LOD = 4 × 10–5 M, respectively. The anti-Hofmeister selectivity of sensors was observed. The electrode based on phenoxy-substituted boron subphthalocyanine and (C16H33)2ImCl was used for the assay of acetylsalicylic acid in the drug Cardiomagnyl.

Design and construction of a new optical solid-state mercury(ii) sensor based on PVC membrane sensitized with colloidal carbon dots

A new Hg2+ ion solid-state double layer sensor impregnated with colloidal carbon dots and N′-(3-(4-(dimethylamino)phenyl)allylidene)isonicotinohydrazide (NDPAI, as a second layer) was inserted in plasticized polyvinyl chloride (PVC) as the first layer.

Novel potentiometric sensors for the determination of the dinotefuran insecticide residue levels in cucumber and soil samples

Five new potentiometric membrane sensors for the determination of the dinotefuran levels in cucumber and soil samples have been developed. Four of these sensors were based on a newly designed molecularly imprinted polymer (MIP) material consisting of acrylamide or methacrylic acid as a functional monomer in a plasticized PVC (polyvinyl chloride) membrane before and after elution of the template. A fifth sensor, a carboxylated PVC-based sensor plasticized with dioctyl phthalate, was also prepared and tested. Sensor 1 (acrylamide washed) and sensor 3 (methacrylic acid washed) exhibited significantly enhanced responses towards dinotefuran over the concentration range of 10−7–10−2molL−1. The limit of detection (LOD) for both sensors was 0.35µgL−1. The response was near-Nernstian, with average slopes of 66.3 and 50.8mV/decade for sensors 1 and 3 respectively. Sensors 2 (acrylamide non-washed), 4 (methacrylic acid non-washed) and 5 (carboxylated-PVC) exhibited non-Nernstian responses over the concentration range of 10−7-10−3molL−1, with LODs of 10.07, 6.90, and 4.30µgL−1, respectively, as well as average slopes of 39.1, 27.2 and 33mV/decade, respectively.The application of the proposed sensors to the determination of the dinotefuran levels in spiked soil and cucumber samples was demonstrated. The average recoveries from the cucumber samples were from 7.93% to 106.43%, with a standard deviation of less than 13.73%, and recoveries from soil samples were from 97.46% to 108.71%, with a standard deviation of less than 10.66%.The sensors were applied successfully to the determination of the dinotefuran residue, its rate of disappearance and its half-life in cucumbers in soil in which a safety pre-harvest interval for dinotefuran was suggested.

Potentiometric Sensor for Povidone-Iodine Determination

Adiiodobromide sensor with a plasticized polyvinylchloride membrane was developed. The sensor contained an ionic associate of diiodobromide and rhodamine B and had a linear response for I2Br- concentrations of 10–6 – 10–1 M with an electrode function slope characteristic of singly charged ions. The sensor was used as an indicator electrode for potentiometric determination of povidone-iodine in pharmaceuticals.