Selective Potentiometric Sensor Research Articles

Surface characterization of barium(II)‐selective potentiometric sensor based on a newly synthesized thiosemicarbazone derivative molecule

AbstractIn this study, we synthesized a new thiosemicarbazone derivative molecule (5) that exhibits sensor properties. The characterization of the synthesized molecule was performed using spectroscopic methods such as 1H−, 13C–NMR, FT–IR and Q–TOF. PVC‐membrane ion‐selective sensors were prepared in which the synthesized molecule was used as an ionophore. Surface images of the prepared sensors were examined by scanning electron microscope (SEM) technique. The prepared sensors exhibited selectivity towards barium(II) ions. The developed barium(II)‐selective sensor had a low detection limit of 5.54×10−7 M in the concentration range of 1.0×10−1–1.0×10−6 M. The proposed barium(II)‐selective sensor had fast response time, good repeatability and stability, and can be manufactured with low cost. The sensor can detect barium(II) ions in various water samples with very high recoveries.

Coated Wire Cobalt (II) Selective Potentiometric Sensor Based on (2,4-Dinitrophenyl)-2-(Diphenylmethylene) Hydrazine

A precisely designed coated-wire cobalt ion-selective electrode (ISE) was created using a poly(vinyl chloride) matrix and 2,4-Dinitrophenyl)-2-(diphenylmethylene) Hydrazine as a neutral carrier. In the concentration range of 5.4×10−8 to 1×10−1 M, this new sensor demonstrated a good linear Nernstian response with a slope of 29.8 mV per decade change and an extraordinarily low detection limit of 3.4×10−8 M. The sensor demonstrated exceptional selectivity for Co (II) ions, outperforming mono-, bi-, and tri-valent other cations, while functioning efficiently in the pH range of 3.1–11.2. The selectivity coefficients (Kij) for the following ions were carefully calculated: Na+, K+, Li+, Ag+, Cr3+, Mn2+, Fe2+, Ni2+, Cu2+, Cd2+, Zn2+, Hg2+, Mg2+, Ca2+. The values of the coefficients ranged from 10−4 to 10−2. This sensor was effectively employed as an indicating electrode during potentiometric titration for cobalt ions alongside EDTA, demonstrating even more of its versatility. In addition, the ISE demonstrated its analytical capabilities by precisely identifying the amounts of cobalt in a range of environmental evaluations.

Development of a Composite Cu(II)-Selective Potentiometric Sensor Based on a Thiourea Derivative Symmetric Schiff Base

Abstract. In the present study, initially, a thiourea derivative symmetric Schiff base, (1E,3E)-1,3-bis(5-bromo-2-hydroxybenzylidene)thiourea, was synthesized and characterized by FTIR and SEM-EDX analysis. In addition, an all-solid-state composite Cu(II)-selective potentiometric sensor based on this synthesized compound as an electroactive substance was constructed. Optimization studies indicated that the composition of the optimum sensing composite exhibiting the best potentiometric characteristics was 3.0% Schiff base, 5.0 % multi-walled carbon nanotube (MWCNT), 20.0 % paraffin oil and 72.0% graphite by mass. The proposed sensor displayed a linear response in the concentration range of 5.0×10-6-1.0×10-1 M with a slope of 31.1 mV/decade and a detection limit of 5.0×10-7 M. The proposed sensor exhibited a fairly selective, stable (potential drift: 1.85 mV/h), and rapid (<10 s) response towards Cu(II) ions. Because of the magnitude of its potential drift, the sensor should be recalibrated along the analysis time at least half an hour apart. The sensor can employed safely in the samples with pHs in the range of 2.0-6.5. The lifetime of the fresh sensor surface was determined as 2 weeks. The most important advantage of the sensor is that the sensing composite surface is renewable (at least 10 times) and thus the sensor can be used many times for a long period of time. The analytical applications of the sensor were executed successfully by using the electrode in the potentiometric titration of Cu(II) ions with EDTA as an indicator electrode, in the direct determination of Cu(II) contents of spiked water samples, and in the determination of (w/w) Cu% content of a Turkish coin.

Expanding the library of sumanene molecular receptors for caesium-selective potentiometric sensors.

This paper reports the synthesis and characterization of eight sumanene molecular receptors for the selective recognition of caesium cations (Cs+). The sumanene derivatives differed in the number (from one to nine), type (electron donating or electron withdrawing) and method of the attachment (functionalization of sumanene at the benzylic or aromatic carbons) of substituents in the sumanene skeleton. The ultimate goal of this work was to investigate the prospective use of various sumanene derivatives in the design of Cs+-selective potentiometric sensors, thus, expanding the library of sumanene receptors for such applications. Spectroscopic fluorescence titration with caesium hexafluorophosphate revealed that the formation of sandwich complexes is highly favourable, but the steric hindrance of bulky substituents can disrupt this preference. In the case of triaryl-substituted sumanene derivatives, theoretical calculations show that, indeed, sandwich complexes are energetically more advantageous by 2.3 times than 1 : 1 complexes. Furthermore, such functionalization significantly increases receptor solubility in the polymeric membrane of the potentiometric sensors, which was quantitatively evaluated with the COSMO model.

Imprinted polymer/reduced graphene oxide-modified glassy carbon electrode-based highly sensitive potentiometric sensing module for imidacloprid detection

A sensitive and highly selective potentiometric sensor for imidacloprid detection (IMD) is presented. Reduced graphene oxide (rGO) was used to modify a glassy carbon electrode in the fabrication of this sensor. The rGO is coated with IMD molecularly imprinted polymer (MIP), which serves as a sensing compound for herbicide recognition. Under ideal circumstances, a linear range of 0.5 µM-1.0 mM was measured, with a detection limit of 0.2 µM IMD. The method exhibits great selectivity towards the IMD's determination, according to the examination of the effects of potentially interfering species. For the direct potentiometric detection of IMD in several pesticide formulation samples, the assay method has been validated and shown to be adequate. The obtained recovery ranges from 94.5 to 106.4 % of the nominal or spiked concentration, with a mean relative standard deviation of 1.3 %. The applicability outcomes of using the presented sensor were contrasted with those attained by high-performance liquid chromatography (HPLC). There was no discernible difference between the suggested and HPLC procedures. Due to the sensitive membrane's and the liquid junction's proximity, this module's use permits applications with a small sample volume. The proposed sensor's effectiveness in a complicated matrix points to applications for rapid detection and tests for quality assurance and control in the agro-industry.

Surface characterization and electroanalytical applications of the newly developed copper(II)-selective potentiometric sensor.

In this work, we developed a new copper(II)-selective potentiometric sensor and investigated its surface with scanning electron microscopy (SEM). Besides the surface images of the sensors conditioned in copper(II) solutions, energy-dispersive X-ray (EDX) and mapping studies were carried out. According to the results obtained, it was determined that copper(II) ions adhered to the porous areas on the sensor surface, and that Cu2+ ions showed a wide distribution on the sensor surface in mapping studies. The new sensor had a Nernstian response of 29.3 ± 0.5mV/decade in the concentration range of 1.0 × 10-1-1.0 × 10-5M and a low detection limit of 8.56 × 10-6M. The proposed sensor had fast response time (< 10s), wide pH working range (5.0-10.0), good repeatability and stability. Finally, the sensor performed the determination of copper(II) ions in various water samples with very high recoveries (96.0-102.0%).

Development of Smart Potentiometric Sensors Covered with Non-Biofouling Layer for Detection of Early Stages of Inflammatory Processes Around Joint Replacements

One of the problems occurring after the joint replacement is connected with the post-surgery infections which are caused by bacteria that form biofilms on surfaces and are referred to as biofilm-related infections (BRI). It is also worth noting that due to the bioresponse, strong pathophysiological changes in the microclimate of an affected surface occur (decrease in pH, formation of various reactive oxygen species (ROS), depletion of Fe ions, and increase in the concentration of Ca ions). In this work we have prepared a robust selective potentiometric sensor of ROS and pH sensor for the detection of pH changes caused by sterile inflammation and bacterial and fungal infections. The ROS sensor consists of a conductive polymer layer based on polythiophene with an incorporated porphyrin-metal complex that potentiometrically detects the presence of ROS (H2O2 and ClO– ions). This sensor is connected by the covalent bonds with a non-biofouling layer of poly(2-methyl-2-oxazoline), which works as a bio-compa­tibilizer. It was shown that the potentiometric sensor shows a rapid response to hydrogen peroxide, does not record any interference with bovine serum albumin as a model serum protein, and is able to fully reversibly detect ROS with a linear response within a wide range of biological relevant concentrations (from 0.05 μM to 10 μM). The sensing electrode based on polyaniline and poly(2-methyl-2-oxazoline) on a titanium alloy support was developed for the potentiometric detection of peri-implant pH changes to enable early detection of the aforementioned pathologies. The developed electrodes show the changing of pH in the range between 5 and 8 for the individual pathogenic bacteria or pathogenic yeast, with a Nernstian slope of −59.6/pH.

Novel (E)−2-((1-(thiophen-2-yl)ethylidene)-amino) phenol Manganese(II) as an Ionophore Based on Thiocyanate-Selective Electrodes and Its Applications

Novel highly selective potentiometric sensor based on aquadichloro(E)−2-((1-(thiophen-2-yl)ethylidene)-amino)phenol manganese(II)trihydrate as an anion carrier. The thiocayanate electrode displayed a very high selectivity compared with others inorganic anions. Different sensors with plasticized PVC membranes have been investigated. The sensors construction containing different amounts of ionophore with and without additives. The pH over 3.5–6.5 range has been studied. Optimized membrane electrode included 66 mg PVC, 132 mg o-nitrophenyloctylether, 10 mol % tetrakis(trifluoromethyl)phenyl borate and 2% [Mn(C12H11NOS)(Cl2)(H2O)]· 3H2O. The optimized sensors exhibit Nernstian response for thiocyanate through a linear concentration ranging from (5 × 10−8 to 9.06 × 10−1 M) with a detection limit of 3 × 10−8 M and a slope of −57.7 mV decade−1, the measurement carried out in acetate buffer pH 4.7. The response time of electrode <10 s and the lifetime of the sensor more than 6 weeks. The proposed electrode was effectively utilized to estimation of thiocyanate in saliva sample, the results revealed a valid agreement with reference colorimetric method.

Development of a potentiometric sensor for the determination of carbamazepine and its application in pharmaceutical formulations

AbstractBACKGROUNDEpilepsy is a neurological disorder and its treatment is carried out with anti–epileptic drugs. Carbamazepine has been in use since 1965, as a safe and effective anti–epileptic agent. In this paper, a poly(vinyl chloride) (PVC) membrane carbamazepine selective potentiometric sensor was developed for the determination of carbamazepine in pharmaceutical formulations. Carbamazepine–tetraphenylborate (CBZ–TPB) ion−pair was synthesized as an electroactive component and PVC membrane sensors were prepared with different CBZ–TPB ratios. The membrane with the best analytical properties was determined as the one with 2.0% CBZ–TPB ion–pair, 33.0% PVC and 65.0% o–nitrophenyl octyl ether (o–NPOE).RESULTSThe proposed sensor exhibited linear responses over the concentration range 1.0 × 10−5 – 1.0 × 10−2 mol L−1 (R2 = 0.999). The limit of detection was 9.60 × 10−6 mol L−1. The developed sensor showed high selectivity against carbamazepine over some ionic species investigated and also over other anti–epileptic drugs. The potentiometric response of the sensor was not affected by pH in the wide pH range of 4.0–9.0 and the response was fast, at ≈10s.CONCLUSIONThe fabricated carbamazepine–selective sensor was applied for the determination of carbamazepine contents of some pharmaceutical formulations. The potentiometric measurement results for the pharmaceutical formulations gave results with good agreement with data obtained using UV–visible spectroscopy. As a result, the developed carbamazepine selective potentiometric sensor can be considered as an alternative to other analytical methods for the determination of carbamazepine in pharmaceutical samples. © 2022 Society of Chemical Industry (SCI).

A potentiometric sensor for the determination of potassium in different baby follow–on milk, water, juice and pharmaceutical samples

Potassium is one of the minerals essential for the human body, and its intake is usually provided from foodstuffs. In this study, a novel potassium selective potentiometric sensor was developed to perform potassium analysis in baby follow–on milk, mineral water, drinking water, fruit juice and drug samples. The potassium selective sensor exhibited a low detection limit of 5.88 × 10−6 mol L−1 over a wide linear range from 1.0 × 10−5 to 1.0 × 10−1 mol L−1. The sensor had a very short response time (< 5 s), good selectivity, good repeatability and high potential stability. In addition, the developed sensor was easy to manufacture with low cost, and it worked independently of pH changes in the pH range of 6.0–10.0. The developed sensor was applied to analysis of various food, drug and water samples and potassium ion determination was carried out with very high recoveries.

A Potentiometric Sensor for the Determination of Pb(II) Ions in Different Environmental Samples

AbstractIn this study, a novel PVC‐based membrane containing (E)‐2‐(1‐(4‐(3‐(4‐chlorophenyl)ureido)phenyl)ethylidene)hydrazine carbothioamide (5) as an electroactive component (ionophore) along with potassium tetrakis (p‐chlorophenyl) borate (KTpClPB) and bis(2‐ethylhexyl)adipate (DEHA) in the ratio 4.0 : 32.0 : 1.0 : 63.0 (ionophore:PVC:KTpClPB:DEHA) (w/w) was used to develop a lead(II)‐selective potentiometric sensor. The sensor exhibited a Nernstian response over a wide concentration range from 1.0×10−5 to 1.0×10−1 mol L−1 with a slope of 28.0±2.0 mV/decade, and a detection limit of 1.65×10−6 mol L−1. It displayed very good selectivity towards Pb(II) ions over other cationic species. The lead(II)‐selective sensor showed a fast response time of 5 s, good repeatability, and it worked in the broad pH range of 5.0–11.0. The sensor could be used as an indicator electrode in the quantification of Pb(II) by potentiometric titration against ethylenediaminetetraacetic acid (EDTA). In addition, this sensor was applied for the direct determination of Pb(II) in different water samples including spring water, purification water, commercial water, waste water and in a waste battery sample.

A novel potentiometric sensor for the determination of Pb(II) ions based on a carbothioamide derivative in PVC matrix

In this research, a carbothioamide derivative molecule was synthesized to be used as an electroactive material, and poly (vinyl chloride) (PVC) membrane lead(II)–selective potentiometric sensors with different components were prepared. Among various compositions, the best potentiometric performance was exhibited by the membrane having the electroactive material, bis(2–ethylhexyl)sebacate (BEHS), PVC, and potassium tetrakis(p–chlorophenyl)borate (KTpClPB) in the ratio of 4.0:63.0:32.0:1.0 (w/w). The proposed sensor exhibited a Nernstian response in the concentration range of 1.0×10-5–1.0×10-1 mol L-1 with a slope of 29.5±1.6 mV/decade. The detection limit of the sensor was 3.96×10-6 mol L-1. The potentiometric response of the lead(II)–selective sensor was independent of pH of test solution in the pH range of 5.0–9.0. The developed sensor had very good repeatability, stability, and selectivity, as well as a response time of 5s. These novel lead(II)–selective sensors, produced cost–efficiently, have been successfully used as an indicator electrode for the potentiometric titration of Pb(II) against EDTA and for the determination of Pb(II) ions in different water samples.

Synthesis and Potentiometric Sensor Applications of a Hydrazone Derivative Molecule: Fast and Selective Determination of Cobalt(II) Ions

AbstractIn this study, a simple and highly selective potentiometric sensor has been developed for the determination of cobalt(II) ions based on a poly(vinly chloride) (PVC) membrane. As an ionophore, a hydrazone derivative molecule (3) was synthesized for the first time, and its characterization was completed using NMR, FT‐IR and Q‐TOF spectroscopic techniques. The developed sensor works well in the linear concentration range of 1.0×10−6–1.0×10−1 Μ with Nernstian slope of 28.6±1.7 mV/decade of activity. The developed cobalt(II)–selective sensor has a low detection limit of 3.09×10−7 Μ, and a very fast response time of 5 seconds. The sensor, which exhibits a highly selective behaviour towards cobalt(II) ions compared to other metal cations, works in the pH range of 6.0–10.0 without being affected by changes in pH. The developed sensor could be used as an indicator electrode in potentiometric titration of Co(II) ions with EDTA. Finally, the developed cobalt(II)‐selective sensor was successfully used for the determination of Co(II) in various water samples.

Selective Detection of Chloroquine in Human Urine with Application at the Point-of-Care

Chloroquine is an important, and commonly prescribed, antimalarial drug which can lead to the development of retinopathy and potential blindness. This paper reports on the design and fabrication of a highly selective potentiometric sensor for chloroquine, demonstrating the first use of ionophore-doped ion-selective electrodes (ISEs) for its detection. Several molecules, with known affinity for chloroquine, were investigated as potential ionophores for the chloroquine ISE. Incorporating melanin as the ionophore resulted in a linear detection range of 10 mM to 2.4 μM and a limit of detection of 630 nM. Importantly, the melanin-doped ISE resulted in an increased selectivity by several orders of magnitude compared to an ionophore-free ISE. This added selectivity allowed for detection of chloroquine without interference from other commonly prescribed antimalarials, hydroxychloroquine and quinine that have similar molecular structures. To determine the applicability of the melanin-doped ISE, chloroquine was successfully measured in human urine samples, and the results of the sensor were validated using a High-Performance Liquid Chromatography (HPLC) protocol. To demonstrate the utility of the sensor, the components of the ISE were translated to a paper-based potentiometric device capable of detecting chloroquine between 10 mM and 100 μM, covering the biologically relevant range excreted in human urine.

Selective potentiometric detection of reactive oxygen species (ROS) in biologically relevant concentrations by a modified metalized polyporphyrine sensing layer coated with nonbiofouling poly(2-alkyl-2oxazoline)s

We built a robust selective potentiometric sensor of reactive oxygen species (ROS) as a thin layer applied on the surface of smart implants, which enables the detection and localization of inflammation at an early stage. The sensor consists of a conductive polymer layer based on polythiophene with an incorporated porphyrin-metal complex that potentiometrically detects the presence of ROS. This sensor is covalently coated with a nonbiofouling layer of poly(2-methyl-2-oxazoline), which works as a biocompatibilizer but mainly prevents the sorption of proteins and other biomacromolecules naturally occurring in organisms, which could interfere with the ROS signal. We have shown that our potentiometric sensor shows a rapid response to hydrogen peroxide, does not experience interference with bovine serum albumin as a model serum protein when sensing ROS, is able to fully reversibly detect ROS with a linear response within a very wide range of biologically relevant concentrations and, most importantly, is able to distinguish between hydrogen peroxide and hypochlorite. We also performed a head-to-head comparison of two positional isomers of thienylated porphyrine for sensor applications (2TTP and 3TTP, with 3TTP shown to be more appropriate) and four different coordinated metals (Cu, Fe, Co and Mn, with Cu and especially Fe shown to be the most appropriate).

Development of Chromium(III) Selective Potentiometric Sensors for Its Determination in Petroleum Water Samples Using Synthesized Nano Schiff Base Complex as an Ionophore.

Many analytical techniques, such as X-ray fluorescence spectrometry, inductively coupled plasma-atomic emission spectrometry, and even traditional spectroscopic and fluorimetric methods, are used for the measurement of Cr(III) ions. These methods are sophisticated and very expensive, so thecheapest and low-cost ion selective electrodes were used. The quantification of Cr(III) ions in various samples of petroleum water using ion selective electrodes was suggested. Nano chromium modified carbon paste sensor (MCPE) and nano chromium modified screen printed sensor (MSPE) based on Schiff base Cr(III) complex are developed. The developed nano Cr(III) Schiff base chelate was characterized using elemental, spectroscopic, and thermal analysis techniques. The proposed nano Cr(III) has good properties for antibacterial and antifungal activity. The modified carbon paste and screen-printed sensors were fabricated for determination of Cr(III) ion. The proposed MCPE (sensor I) and MSPE (sensor II) obeys Nernstian equation upon incorporating nano Cr(III) ionophore in the paste at 25°C with a trivalent cationic slope of 18.8 ± 0.2 and 20.0 ± 0.4 mV/decade. They have showed fast response time around 8 and 5 s, and they may be used for at least 98 and 240 days without significant changes in MCPE and MSPE potential, respectively. The sensors I and II showed good selectivity for Cr(III) ion toward a wide variety of metal ions or anions as confirmed by potentiometric selectivity coefficients values. The detection and quantification limits were defined alongside the other process validation parameters. The results have been compared well to those obtained by atomic absorption spectrometry (AAS), and the data of F- and t-test indicated no significant difference between the proposed and AAS methods. These sensors have been used to determine Cr(III) ions in genuine spiked different petroleum well water samples with satisfactory percentage recoveries, low standard, and relative standard deviation values using direct potentiometric and standard addition methods. The proposed method of producing nano Cr(III) complex as a sensor material possesses the distinct advantages of being simple, easily reproducible, appropriate for operation, and highly selective and sensitive. Modified carbon paste and screen-printed electrodes were fabricated based on nano Cr(III) complex as ionophore. The electrodes follow Nernstian behavior, and they optimized according to IUPAC recommendation. They showed a high selectivity for Cr(III) ion over many bi- or trivalent metal ions and anions. The results obtained compared well with those obtained using AAS. They successfully applied for determination of Cr(III) in petroleum water samples.

A new approach for determination of water soluble hexavalent chromium in real cement and industrial water samples using Ni-Fe layered double hydroxides/urea/glycerol nanocomposite based potentiometric sensor

Hexavalent chromium (Cr (VI)) is considered one of the most toxic elements that directly affects human health and the environment. Therefore, in this study, two sensitive and selective potentiometric sensors are proposed for Cr (VI) detection in various real cement and industrial water samples based on Ni-Fe layer double hydroxides/urea (Ni-Fe LDH/UA) (sensor I) and Ni-Fe LDH/UA/Glycerol (sensor II) nanocomposites using 1,3-didecyl-2-methylimidazolium-Chromate ion-pair (TEGO-Cr) and cetylpyridinium bromide (CPB). Also, the current study discussed the reducing effect of the alkaline sulfur solution on Cr (VI) and other effects on cement properties. The examined sensors presented excellent Nernstian slopes with short response times (<8 s). The fabricated sensors showed a lower detection limit reached 6.0 × 10−8 mol L−1 (3.0 µg L−1) over a wide pH range (4–9). The proposed potentiometric sensors were successfully performed for Cr (VI) determination in real cement and industrial water samples. The present study presented that sulfur solution can be used conveniently to reduce Cr (VI) in the cement industry without any negative effect on the concrete properties of cement.

A novel chloride selective potentiometric sensor based on graphitic carbon nitride/silver chloride (g-C3N4/AgCl) composite as the sensing element

In this research, AgCl anchored graphitic carbon nitride (g-C3N4) was introduced as a novel potentiometric sensing element. A g-C3N4/AgCl-modified carbon paste electrode (CPE) was fabricated and used as an outstandingly selective potentiometric sensor to determine Cl− in water samples. The g-C3N4/AgCl nanocomposite was characterized with SEM, XRD and FT-IR techniques. It was demonstrated that, the incorporation of 5% of g-C3N4/AgCl, as a chloride ionophore in a CPE, results in a stable potential response of the electrode to chloride ion. The Nernstian slope of the electrode response was 55.4 (±0.3) mVdecade−1, over a wide linear concentration range of 1 × 10−6–1 × 10−1 mol L−1 and the detection limit of the electrode was estimated to be 4.0 × 10−7 mol L−1. The g-C3N4/AgCl-modified CPE electrode provided fast response time and long-term stability (more than 2 months) while the potential interfering ions such as I−, Br−, and CN− showed no significant effect on the potential response. Since these interfering ions affected the response of the CPE electrode, modified with AgCl, highlighting the interesting effect of g-C3N4 on the sensor performance. This innovative electrode was shown to be a sensitive and accurate sensor for chloride ion content estimation in water samples.

Novel Zn‐Fe LDH/MWCNTs and Graphene/MWCNTs Nanocomposites Based Potentiometric Sensors for Benzydamine Determination in Biological Fluids and Real Water Samples

AbstractTwo sensitive and selective potentiometric sensors based on zinc‐iron layered double hydroxides/multiwalled carbon nanotubes (Zn−Fe LDH/MWCNTs) (sensor I) and graphene/multiwalled carbon nanotubes (Gr/MWCNTs) (sensor II) nanocomposites were developed for benzydamine hydrochloride (Benz) determination. The investigated sensors displayed excellent Nernstian slopes 58.5±0.7 and 59.5±0.5 mV decade−1, detection limits 8.3×10−7 and 1.9×10−7 mol L−1, long lifetimes, adequate selectivity, high chemical, and thermal stability within pH range of 2.4–8.5 for sensors І and ІІ, respectively. The surface morphology of sensors was analyzed using a Transmission Electron Microscope (TEM). The analytical method was efficiently implemented for Benz determination in biological fluids and surface water samples.

Novel and selective potentiometric sensors for Cinchocaine HCl determination in its pure and Co-formulated dosage form: A comparative study of in situ carbon sensors based on different ion pairing agents

Promising in situ carbon paste electrodes (ICPEs) have been fabricated for selective cinchocaine HCl (CIN.HCl) determination in its pure form and as co-formulated with other drugs in its pharmaceutical preparation (Otal). The fabricated ICPEs were modified with various ion pairing agents as sodium tetraphenylborate (NaTPB), phosphotungstic acid (PTA), phosphomolybdic acid (PMA) and ammonium reineckate (RN) as an electroactive material. A comparative study of the established ICPEs based on 6 mg PMA (electrode I), 6 mg PTA (electrode II) and 9 mg RN (electrode III) ion pairing agents was conducted with considering the optimization of the developed sensors performance characteristics. The developed sensors I, II and III exhibited a fast and linear response for the monovalent CIN.HCl drug over the spacious concentration range from 1.0 × 10–5 to 1.0 × 10–2 mol L-1 achieving superior Nernstian slope values of 59.80 ± 0.14, 59.20 ± 0.10 and 59.20 ± 0.24 mV decade-1, respectively, reflecting no deviation from the Nernstian behavior over the pH range of 2.5–7. The aforementioned sensors displayed a good distinguishing power for CIN.HCl over the other cations, sugars and other co-formulated drugs. Additionally, validation parameters have been studied according to the IUPAC recommendations. The proposed electrodes have been employed with a promising success for determining CIN.HCl in Otal (ear drop) with good relative standard deviation values. Moreover, the inter- and intra-day accuracy (expressed as recovery %) and precision (expressed as relative standard deviation %) of the established CIN.HCl selective potentiometric method have been studied. As, the inter-day accuracy and precision ranges were found to be 99.46–100.1, 99.59–99.90 and 99.58–100.3% and 0.315–0.844, 0.263–1.199 and 0.328–0.703% while the intra-day accuracy and precision ranges were 99.62–101.4, 99.59–100.5 and 99.71–100.5% and 0.263–1.220, 0.471–0.877 and 0.528–0.885% for the established sensors I, II and III in the CIN.HCl pharmaceutical form (Otal), respectively.