A PVC Membrane Sensor for Potentiometric Determination of Atorvastatin in Biological Samples and Pharmaceutical Preparations

The present article reports for the first time the use of Aliquat 336S‐atorvastatin as an electroactive material in a poly(vinyl chloride) matrix membrane sensor plasticized with ortho‐nitrophenyl‐octylether (o‐NPOE) or dioctylphthalate (DOP) for determination of atorvastatin in biological samples (human plasma) and in pharmaceutical preparations. The sensor shows fast, stable and reproducible response over the concentration range of 1.0×10^?7–1.0×10^?2 mol L^?1 atorvastatin with anionic slopes of 60.94±0.2 and 58.22±0.2 and pH range of 5.0–9.0 for o‐NPOE and DOP plasticized based membrane sensors, respectively. The response time of the sensor is stable and fast (10 s). Results were achieved with average recoveries of 99.5 % and 99.3 % and mean standard deviations of ±1.1 % and ±1.4 % for o‐NPOE and DOP plasticized based membrane sensors, respectively. The sensor exhibits high selectivity towards atorvastatin in the presence of many anions, drug excipients and diluents. Validation of the method according to the quality assurance standards shows suitability of the proposed sensors for use in the quality control assessment of the drug.     

Determination of Dysprosium(III) Ion in Soil and Sediment Samples by an Original Potentiometric Dysprosium(III) Membrane Sensor

Abstract

A PVC membrane electrode for dysprosium(III) [Dy(III)] ions was constructed, having its basis on benzoxazoleguanidine (BG) as a suitable ionophore. The sensor presents a linear dynamic range of 1.0 × 10^?6–1.0 × 10^?1 M, with a Nernstian slope of 19.5 ± 0.4 mV decade^?1 and a detection limit of 4.7 × 10^?7 M. The response time is quick (less than 10 s). It can be used in the pH range of 3.3–8.4, and its duration is at least 2 mo without any considerable, noticeable potential divergence. The recommended sensor revealed comparatively good selectivity with respect to most alkali, alkaline earth, some transition, and heavy metal ions. It was successfully employed as an indicator electrode in the potentiometric titration of Dy(III) ions with EDTA. The membrane sensor also applied to the determination of concentration of Dy(III) ions in soil and sediment samples. Validation with certified reference materials (CRMs) was also carried out.     

Determination of Fluoride Ions in Mouthwash Samples by a PVC Membrane Samarium(III) Sensor

Abstract

In this study, a new ion-selective electrode for Sm³⁺ is described, illustrating 2-[(E)-1-(1H-pyrrol-2-yl)methylidene]-1-hydrazinecarbothioamide (PMH) in a poly(vinylchloride) (PVC) membrane with nitrobenzene (NB) as a plasticizer and sodium tetraphenyl borate (NaTPB) as an anionic additive. The proposed sensor exhibited a Nernstian response for Sm³⁺ ions over a wide concentration range between 1.0 × 10^?2 and 1 × 10^?6 M, with a detection limit of 5.2 × 10^?7 M in the pH range of 4.2–8.5. Moreover, the sensor displayed the Nernstian slope of 19.8 ± 0.3 mV per decade, having a fast response time within 10 s over the entire concentration range. This electrode presented very good selectivity and sensitivity toward the Sm³⁺ ions over a wide variety of cations, including alkali, alkaline earth, transition-metal, and heavy-metal ions. It was used as an indicator electrode in the potentiometric titration of Sm³⁺ ions with EDTA. The membrane sensor was also applied to the determination of fluoride ions in mouthwash samples.     

Determination of Ytterbium(III) Ions in Soil and Sediment Samples by a New Polymeric Yb3+-PVC Membrane Sensor

Abstract

A polyvinyl chloride (PVC) membrane sensor for ytterbium(III) ions was prepared, based on 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene (BBT) as a membrane carrier. The sensor illustrates the following characteristics: a linear dynamic range of 1.0 × 10^?6 to 1.0 × 10^?2 M; a Nernstian slope of 19.7 ± 0.5 mV decade^?1; a detection limit of 4.4 × 10^?7 M; a response time of <10 s; and use for at least 2 months without any significant potential divergence in the pH range of 3.5–8.4. Moreover, the recommended selective sensor revealed a comparatively satisfactory selectivity regarding most of the alkali and alkaline earth ions and some of the transition-metal and heavy-metal ions. In fact, it was used as an indicator electrode in the Yb(III) potentiometric titration with ethylene diamine tetra-acetic acid (EDTA) and the determination of concentration of Yb(III) ions in soil and sediment samples.     

Determination of Salbutamol, Amikacin and Paromomycin Sulfate by a Novel Sulfate Polymeric Membrane Sensor Based on 2,6-diphenyl 4-(4-methoxyphenyl) pyrylium perchlorate

A novel sulfate polymeric membrane sensor based on 2,6-diphenyl 4-(4-methoxyphenyl) pyrylium perchlorate (DMPP) as a sensing material is presented. The electrode displays a very low detection limit (4.0×10^–7M) and wide working concentration range (8.0×10^–7–1.0×10^–1M). The sensor shows remarkable selectivity toward sulfate over most common organic and inorganic anions, including chloride, acetate, nitrate, nitrite, bromide, iodide, thiocyanate, phosphate, fluoride, sulfite, hydrogen sulfite, hydrogen carbonate, citrate, tartarate and oxalate. The sensor reveals a Nernstian behavior (slope of –29.7±0.5mV per decade) in a wide pH range (3.0–9.5). The proposed sensor shows a short response time over the entire working range (15s) and was successfully applied to the direct determination of salbutamol, amikacin and paromomycin sulfate.     

Lead-Selective Membrane Potentiometric Sensor Based on a Recently Synthesized Bis(Anthraquinone) Sulfide Derivative

Abstract

A new PVC membrane electrode for lead ions, based on bis[(1-hydroxy-9,10-anthraquinone)-2-methyl]sulfide as membrane carrier, was prepared. The sensor exhibits a Nernstian response for Pb²⁺ over a wide concentration range (5.6 × 10^?3-4.0 × 10^?6 M). It has a response time of about 30 s and can be used for at least 3 months without any divergence in potentials. The proposed membrane sensor revealed good selectivities for Pb²⁺ over a wide variety of other metal ions. It was used as an indicator electrode in potentiometric titration of lead ion.     

Original Potentiometric Ytterbium(III) PVC-Membrane Sensor Based on N1,N2-Bis-[1-(2-hydroxy-1,2-diphenyl)ethylidene]ethanedihydrazide

Abstract

In this work, we describe the construction, performance, and applications of an original ytterbium(III) sensor based on N¹,N²-bis-[1-(2-hydroxy-1,2-diphenyl)ethylidene]ethanedihydrazide (BHDEH), which acts as a suitable carrier. Because it has a low detection limit of 4.2 × 10^?7 M, the sensor response for the Yb(III) ion is Nernstian over a wide concentration range: four decades of concentration (1.0 × 10^?6 to 1.0 × 10^?2 M). The response time of the electrode is less than 10 s, it can be used in the pH range of 3.2–8.3, and its duration is at least 2 months without any considerable potential divergence. The sensor revealed very good selectivity for Yb(III) in the presence of several metal ions. To investigate the sensor analytical applicability, it was tested as an indicator electrode in the potentiometric titration of Yb(III) solution with standard EDTA solution. The proposed electrode was also used to determine fluoride ions in mouthwash.     

Novel Nitrite Membrane Sensor Based on Cobalt(II) Salophen for Selective Monitoring of Nitrite Ions in Biological Samples

A novel PVC-based membrane sensor based on the Co(II)-salophen complex (CSC) is described. The electrode revealed a Nernstian response over a wide nitrite ion concentration range (1.0×10^–6–1.0×10^–1M). The detection limit of the sensor is 8.0×10^–7M. The best performance was obtained with a membrane composition of 33% PVC, 61% ortho-nitrophenyloctyl ether, 3% cobalt(II)-salophen, and 3% hexadecyltrimethylammonium bromide. The potentiometric response of the sensor is independent of the pH of solution in the pH range 4.5–11.9. The electrode exhibits a very fast response time and good selectivity over a variety of common inorganic and organic anions, including fluoride, bromide, iodide, sulfite, nitrate, thiocyanate, thriiodide and perchlorate. The selectivity behavior of the proposed sensor shows substantial improvements compared to the previously reported electrodes for nitrite ion. The membrane sensor can be used for at least 2 months without any divergence in potential. The electrode was successfully applied to the monitoring of nitrite ion in water, sausage, flour, wheat, cheese and milk.     

Miniaturized Verapamil Soild-State Potentiometric Sensors Based on Native Ionic Polymers

 Novel miniaturized carboxylated poly(vinyl chloride) and poly fluoro sulfonate (Nafion) matrix membrane sensors in an all-solid state graphite support were developed, electrochemically evaluated and used for the assay of verapamil drug. These sensors incorporate the native polymers without plasticizer and/or drug-ion pair complex. Upon soaking these sensors in verapamil test solution, electroactive self regenerated membranes are formed and a near-Nernstian potentiometric response is induced for verapamil over the concentration range 1×10⁻²–1×10⁻⁵ M with a cationic slope of 56–57 mV decade⁻¹ of concentration. Inherent advantages of these sensors include fast response (<10 s), long life time (>6 months), good thermal stability (up to 60 °C), high sensitivity (down to 1 μg ml⁻¹), extended working pH range (2–8) and reasonable selectivity. Verapamil could be determined in various dosage forms with an average recovery of 98.8% (st.dev. 0.8%) of the nominal concentration without any significant interferences from various excipients and diluents commonly used in drug formulations. Received August 17, 1998. Revision February 9, 1999.     

A Potentiometric Method for Determination of Oxidized Ketone Bodies in Milk

Following the decarboxylation of acetoacetic acid by heating and the separation of acetone from milk matrix by steam distillation, acetone was allowed to react with bromine in the presence of nitric acid, causing the formation of bromoacetone and bromide; the latter was then quantified by means of a suitable ion-selective electrode applying the calibration principle. Based on checking reproducibility and on comparative analyses performed by a widely accepted photometric method, the potentiometric method developed was found to be adequate for the determination of the oxidized ketone bodies.     

Novel Membrane Potentiometric Thiocyanate Sensor Based on Tribenzyltin(IV) Dithiocarbamate

A novel PVC membrane ion‐selective electrode based on tribenzyltin(IV) dithiocarbamate [Sn(IV)–TBDTB] as neutral carrier was developed for thiocyanate (SCN^?) determination. The electrode exhibits a near‐Nernstian response for SCN^? with a slope of 62.8±2.0 mV per decade over a wide concentration range 1.0×10^?1–2.0×10^?6 mol L^?1 and a detection limit of 1.0×10^?6 mol L^?1 in MES–NaOH buffer, pH 6.0, at 25 °C. The electrode prepared with 1.5 wt.% Sn(IV)–TBDTB, 32.5 wt.% PVC and 66.0 wt.% 2‐nitrophenyloctyl ether (o‐NPOE) shows optimal response characteristics. Anti‐Hofmeister selectivity sequence for a series of anions shown by the electrode was as follows: SCN^?>Sal^?>I^?>ClO >phCOO^?>CH₃COO^?>Br^?>Cl^?>NO >NO >Citrate>SO₄^2?. The useful pH range for the electrode was found to be 3–7 with a response time 30–40 s. The electrode has been used for direct determination of thiocyanate in wastewater with satisfactory results.     

Potentiometric Flow Injection Analysis of Anionic Surfactants in Industrial Products and Wastes

A new sensor for anionic surfactants with a membrane consisting of 33wt% poly(vinyl chloride) (PVC), 66wt% dioctylphthalate (DOP) plasticizer, and 1wt% tridodecylmethylammonium chloride (TDMAC) is developed and used for flow injection analysis. The sensor displays a working response range of 5×10^–7–5×10^–3M dodecylbenzene sulfonate (DBS^–) with a Nernstian slope of 58.5±0.2mV decade^–1, a response time of 30s and a detection limit of 1.5×10^–7M DBS^–. Selectivity measurements with different anionic species indicate good membrane selectivity towards DBS^–. The sensor is used to measure anionic surfactants (DBS^–) in different wastewater samples, commercial detergent products, and for monitoring the rate of surfactant biodegradation in sewage treatment plants. The results obtained agree fairly well with data obtained by the standard extraction-spectrophotometric method. The proposed potentiometric method offers the advantages of simplicity, accuracy, automation feasibility, and applicability to turbid and colored sample solutions.     

铜的催化动力学电位法测定

本文报道了利用碘离子选择电极监测Ｈ２Ｏ２－ＫＩ氧化还原反应体系被Ｃｕ（Ⅱ）催化的反应速度，建立了测定Ｃｕ（Ⅱ）的催化动力学方法，其线性范围为１０－８０ｎｇ／ｍＬ，该法用于铝合金标样中铜的测定，结果非常接近标准样品的标准值，相对标准偏差为０．３６％，回收率在９８．３％－１０５．６％之间。     

New Ion‐Pair Based All‐Solid‐State Surfactant Sensitive Sensor for Potentiometric Determination of Cationic Surfactants

Cationic surfactants of different types were determined using a few potentiometric sensors based on ion‐pair complexes (dodecyldimethylbenzylammonium dodecylsulfate, dodecylmethylbenzylammonium dodecylbenzensulfonate, tetrahexadecylammonium dodecylsulfate and Hyamine (benzethonium dodecylsulfate)) as sensing materials. The response of the all‐solid state surfactant sensitive electrode based on a Teflonized graphite conducting substrate, coated with a PVC membrane containing sensing material, was investigated in the solutions of Hyamine and hexadecyltrimethylammonium ion in the concentration range from 1 μM to 10 mM. Potentiometric surfactant cation titration has been performed using sodium dodecylsulfate as titrant and an ion‐pair‐based surfactant sensitive electrode as a potentiometric indicator. Several commercial surfactant products have also been titrated and the results were compared with those obtained with two‐phase standard titration method.     

Improved Performance of the Potentiometric Biosensor for the Determination of Creatinine

Abstract

Contemporary methods of analyzing creatinine engage chemicals harmful to the environment and generate large volumes of waste disposals. By introducing a membrane‐based potentiometric biosensor with immobilized creatinine deaminase, the measurements can be performed by miniaturized portable devices that are easy to handle and allow rapid analysis with minimum consumption of chemicals. Thus, the enzymatic creatinine biosensors were revisited and optimized with respect to repeatability, sensitivity, limit of detection (LOD), and response time. A detection limit of 0.3 µM and a sensitivity of 58.78±0.03 mV (23.5°C) were obtained in tris buffer at pH=7.4 after introduction of shielding of all electronics and software filtering. Measurements performed by flow injection analysis (FIA) showed that the response time could be lowered to approximately 30 sec using sample volumes of 30 µl. Interferences were corrected for by application of the Nicolsky‐Eisenman equation, thus allowing determination of creatinine in matrices resembling those of clinical measurements. Investigations of sandwich structures showed that the sensitivity decreased as a function of the number of membranes on top of the immobilized layer of active creatinine deaminase. It was thus shown that the sensitivity depends on the distance of diffusion of species from the sample solution through the membranes to the enzyme.     

Sm3+ Potentiometric Membrane Sensor as a Probe for Determination of Some Pharmaceutics

The increase use of ion sensors in the fields of environmental, agricultural, and medical analysis is stimulating analytical chemists to develop new sensors for fast, accurate, reproducible, and selective determination of various ions. In this study a new samarium membrane sensor was constructed and for the first time, it was applied as a probe in indirect determination of hyoscine, homatropine, and tramadol drugs in their pharmaceutical formulation. The proposed membrane sensor was constructed based on a membrane containing 2% sodium tetraphenyl borate (NaTPB) as an anionic additive, 63% dibutyl phthalate (DBP) as solvent mediator, 5% ionophore, and 30% poly(vinyl chloride) (PVC). The proposed Sm(III) electrode exhibits a Nernstian response of 19.35±0.2 mV per decade of samarium concentration, and has a lower detection limit of 1.0×10^?7 M. The linear range of the sensors was 1.0×10^?7–1.0×10^?1 M. It works well in the pH range of 3.0–8.0.     

Facile Synthesis and Characterization of 5-[(3-Methylthiophene-2-yl-methyleneamino)]-2-mercaptobenzimidazole and Its Potentiometric Sensor Application in a Polyvinyl Chloride Membrane for the Determination of Copper(II)

A novel Schiff base designated as 5-[(3-methylthiophene-2-yl-methyleneamino)]-2-mercaptobenzimidazole was synthesized and characterized. A polyvinyl chloride-membrane potentiometric copper(II)-selective sensor was prepared by using the synthesized 5-[(3-methylthiophene-2-yl-methyleneamino)]-2-mercaptobenzimidazole compound. The prepared polyvinyl chloride-membrane copper(II)-selective sensor exhibited very good selectivity and sensitive potentiometric response towards copper(II) ions compared to a wide variety of other cations. The sensor had a fast response time of <5?s, and showed a linear Nerstian behavior to copper(II) ions over a wide concentration range from 1.0?×?10^?5 to 1.0?×?10^?1 mol L^?1 with a slope of 29.2?±?0.7 and correlation coefficient of 0.9998. The prepared polyvinyl chloride-membrane copper(II)-selective sensor was used for 14 weeks without any significant change in its potentiometric response. The potentiometric response of the developed sensor was highly repeatable. Additionally, the developed sensor was used as an indicator electrode for the potentiometric titration of copper(II) ion with ethylenediaminetetraacetic acid. The sensor was also successfully applied to the direct determination of copper(II) ions in tap water, river water, and dam water samples.     

A Novel Potentiometric Membrane Sensor Based on Aryl Palladium Complex for Selective Determination of Thiocyanate in the Saliva and Urine of Cigarette Smokers

A highly selective potentiometric sensor for thiocyanate ion based on the use of a newly synthesized organo‐palladium ion exchanger complex dispersed in a plasticized poly(vinyl chloride) membrane is described. The sensor displays a Nernstian response (?57.8±0.2 mV decade^?1) over a wide linear concentration range of thiocyanate (1.0×10^?6–1.0×10^?1 mol L^?1 ), low detection limit (6.3×10^?7 mol L^?1), fast response (20 s), stable potential readings (±0.4 mV), good reproducibility (±0.9%), long term stability (8 weeks), high precision (±0.7%) and applicability over a wide pH range (4–10). Negligible interferences are caused by F^?, Cl^?, I^?, Br^?, NO₃^?, NO₂^?, CN^?, SO₄^2?, S₂O₃^2?, PO₄^3?, citrate, acetate and oxalate ions. Under hydrodynamic mode of operation (FIA), the calibration slope is ?51.1±0.1 mV decade^?1, the linear response range is 1.0×10^?5–1.0×10^?1 mol L^?1 SCN^? and the sample throughput is 40–45 per hour. The sensor is satisfactory used for manual and flow injection potentiometric determination of SCN^? in the saliva and urine of cigarette smokers and non smokers. The data agree fairly well with results obtained by the standard spectrophotometric technique. Direct potentiometry and potentiometric titration of SCN^? with Ag⁺ are also monitored with the sensor.     

Lead(II)-Selective Membrane Electrode Based on Tetraphenylporphyrin

ABSTRACT

A PVC membrane electrode for Pb² ions based on tetraphenylporphyrin was prepared. The sensor exhibits a Nernstian response for lead ions over a wide concentration range (1.0 x 10^?5-1.0 x 10^?2 M). The limit of detection is 8.5 x 10^?6M. It has a response time of 15 s and can be used for at least three months without any divergence in potential. The proposed electrode shows a fairly good discriminating ability towards Pb² ion in comparison to some alkali, alkaline earth, transition and heavy metal ions. The electrode can be used in the pH range 5.0 to 7.5. It was used as an indicator electrode in potentiometric titration of lead ion.     

测定盐酸西布曲明的电位传感器的研制与应用

以四苯硼酸钠与盐酸西布曲明生成的离子缔合物为电活性物质,研制了盐酸西布曲明传感器。试验表明:盐酸西布曲明聚氯乙烯(PVC)膜传感器对盐酸西布曲明具有良好的选择性和电位响应特性。在pH 5的溶液中,电极电位呈现近能斯特响应,线性范围为1.0×10-6～1.0×10-1mol.L-1,斜率为50 mV.pc-1(26℃),检出限(3S/N)为5.62×10-7mol.L-1。将电极用于药物中盐酸西布曲明含量的测定,测得回收率为97.3%～100.2%,测定值的相对标准偏差(n=5)均小于2%。