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

BACKGROUND: 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 the cheapest and low-cost ion selective electrodes were used. OBJECTIVE: 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. METHOD: 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. RESULTS: 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. CONCLUSIONS: 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. HIGHLIGHTS: 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.

Selective and sensitive electrochemical sensors based on an ion imprinting polymer and graphene oxide for the detection of ultra-trace Cd(ii) in biological samples.

New selective and sensitive electrochemical sensors were designed based on the deposition of a promising ion imprinted polymer (IIP) on the surface of glassy carbon electrode (GCE) for the detection and monitoring of Cd(ii) in different real samples. Herein, a highly selective Cd-imprinted polymer was successfully synthesized using a novel heterocyclic compound based on the benzo[f]chromene scaffold that acted as a complexing agent and a functional monomer in the presence of azobisisobutyronitrile (initiator) and ethylene glycol dimethacrylate (cross-linker). The characterization of the synthesized chelating agent and IIP was performed using FT-IR, SEM, 1H-NMR, EIMS, and EDX analyses. After that, the voltammetric sensor was manufactured by introducing graphene oxide (GO) on the surface of GCE; then, the IIP was grown by a drop coating technique. The electrochemical characterization of the voltammetric sensor (IIP/GO@GCE) was performed by CV and EIS. For comparison, the potentiometric sensor was also prepared by embedding IIP in plasticized polyvinyl chloride and depositing it as one layer on the GCE surface. Anodic stripping voltammetry was used to construct the calibration graph; the IIP/GO@GCE exhibited a wider detection range (4.2 × 10-12-5.6 × 10-3 mol L-1) and extremely low detection limit (7 × 10-14 mol L-1) for Cd(ii). Meanwhile, the potentiometric sensor showed a linear calibration curve for Cd(ii) over a concentration range from 7.3 × 10-8 mol L-1 to 2.4 × 10-3 mol L-1 with a detection limit of 6.3 × 10-10 mol L-1. Furthermore, both sensors offered outstanding selectivity for Cd(ii) over a wide assortment of other common ions, high reproducibility, and excellent stability.

Design and construction of an electrochemical sensor for the determination of cerium(iii) ions in petroleum water samples based on a Schiff base-carbon nanotube as an ionophore.

A carbon paste sensor (CPE) and screen-printed sensor (SPE) for Ce(iii)-selective determination were prepared using a 2,6-pyridine dicarbomethine-triethylene tetraamine macrocyclic Schiff base ligand (PDCTETA) and multi-walled carbon nanotubes (MWCNTs) as good sensing materials. With respect to most common cations, such as alkali, alkaline earth, transition, and heavy metal ions, the electrodes display high selectivity for the Ce(iii) ion. The sensors respond to Ce(iii) ions in a linear range of 1 × 10-7 to 1 × 10-1 and 1 × 10-8 to 1 × 10-1 mol L-1 with a slope of 18.96 ± 0.73 and 19.63 ± 0.51 mV per decade change in concentration with a detection limit of 1.10 × 10-8 and 5.24 × 10-9 mol L-1 for CPE (sensor IV) and SPE (sensor VIII), respectively. The sensors were found to have a lifetime of 102 and 200 days. The suggested electrodes performed well throughout the pH ranges of 3.5-8.0 and 3.0-8.5, with response times of 8 and 6 seconds for sensor IV and sensor VIII, respectively. The sensors have been used to measure Ce(iii) ions in water samples from several petroleum wells. They have also been utilized as indicator electrodes in Ce(iii) ion potentiometric titrations with EDTA. The results were quite similar to those obtained by employing atomic absorption spectrometry (AAS).

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%).

New Potentiometric Screen-printed Sensors for Determination of Trimebutine Drug in Tablets, Serum and Urine Samples.

A new sensit4e and select4e modified screen printed electrodes (MSPEs) and carbon paste electrodes (MCPEs) were studied in order to determine trimbutine maleate (TM) in pure, tablets, urine, and serum samples. These sensors were embodied with multiwalled carbon nanotubes (MWCNTs) since it improved the quality of the sensors in presence of potassium tetrakis (p-chlorophenyl) borate (KTpClPB) ionophore. A good Nernstian response for the constructed sensors, at optimum paste composition, was exhibited for determination of TM in concentration range of 1.5 × 10-7 - 1.0 × 10-2 and 1.0 × 10-7- 1.0 × 10-2 mol L-1 at 25 °C with detection limit of 1.5 × 10-7 and 1.0 × 10-7 mol L-1 for MCPE and MSPE, respect4ely. It seemed that the potential of the electrodes was independent on pH in the range of 2.0-8.0, 2.0-8.5, 2.0-8.5, and 2.0-9.0 g4ing slope as 56.77 ± 1.11, 57.82 ± 0.54, 57.95 ± 0.37, and 58.99 ± 0.28 mV decade-1 for electrodes 1, 2, 3 and 4, respect4ely. MCPEs and MSPEs gave response time about 8 and 6 s with long lifetime (more than 3 and 5 months), respect4ely. A high select4ity of sensors was observed for TM regarding to a large number of interfering species. The constructed sensors were successfully applied for determination of TM in pure form, its pharmaceutical preparations and biological fluids using standard addition, calibration, and potentiometric titration methods with high precision and accuracy. The results showed a good agreement between the proposed method and the HPLC official method.

Development of Novel Potentiometric Sensors for Determination of Lidocaine Hydrochloride in Pharmaceutical Preparations, Serum and Urine Samples.

This article is focused on the determination of lidocaine hydrochloride as a local anaesthetic drug. A potentiometric method based on modified screen-printed and modified carbon paste ion-selective electrodes was described for the determination of lidocaine hydrochloride in different pharmaceutical preparations and biological fluids (urine and serum). It was based on potentiometric titration of lidocaine hydrochloride using modified screen-printed and carbon paste electrodes as end point indicator sensors. The influences of the paste composition, different conditioning parameters and foreign ions on the electrodes performance were investigated and response times of the electrodes were studied. The electrodes showed Nernstian response of 58.9 and 57.5 mV decade-1 in the concentration range of 1×10-7-1×10-2 and 6.2×10-7-1×10-2 mol L-1 for modified screen-printed and carbon paste electrodes, respectively. The electrodes were found to be usable within the pH range of 2.0-8.0 and 2.0-7.5, exhibited a fast response time (about 6 and 4) low detection limit (1×10-7 and 6.2×10-7 mol L-1), long lifetime (6 and 4 months) and good stability for modified screen-printed (Electrode VII) and carbon paste electrodes (Electrode III), respectively. The electrodes were successfully applied for the determination of lidocaine hydrochloride in pure solutions, pharmaceutical preparation and biological fluids (urine and serum) samples. The results obtained applying these potentiometric electrodes were comparable with British pharmacopeia. The method validation parameters were optimized and the method can be applied for routine analysis of lidocaine hydrochloride drug.

Modified screen-printed ion selective electrodes for potentiometric determination of sodium dodecylsulfate in different samples.

Fabrication and general performance characteristics of novel screen-printed sensors for potentiometric determination of sodium dodecylsulfate (SDS) are described. The sensors are based on the use of ion-association complexes of SDS with cetylpyridinium chloride (electrode I) and cetyltrimethylammonium bromide (electrode II) as exchange sites in a screen-printed electrode matrix. Electrodes (I) and (II) show fast, stable, and near-Nernstian response for the mono-charge anion of SDS over the concentration range of 1×10(-2) - 5.8×10(-7) and 1×10(-2)-6.3×10(-7) mol/L at 25°C and the pH range of 2.0-9.0 and 2.0-8.0 with anionic slope of 57.32±0.81 and 56.58±0.65 mV/decade, respectively. Electrodes (I) and (II) have lower LODs of 5.8×10(-7) and 6.3×10(-7) mol/L and response times of about 8 and 13 s, respectively. Shelf life of 5 months for both electrodes is adequate. Selectivity coefficients of SDS related to a number of interfering cations, and some inorganic compounds were investigated. There were negligible interferences caused by most of the investigated species. The direct determination of 0.10-13.50 mg of SDS by electrodes (I) and (II) shows average recoveries of 99.96 and 99.85%, and mean RSDs of 0.83 and 1.04%, respectively. In the present investigation, both electrodes were used successfully as end point indicators for determination of SDS in pure pharmaceutical preparations and real spiked water samples. The results obtained using the proposed sensors to determine SDS in solution compared favorably with those obtained by the standard addition method.

Novel screen-printed electrode for the determination of dodecyltrimethylammonium bromide in water samples.

The construction and electrochemical response characteristics of a screen-printed electrode (SPE) for the determination of dodecyltrimethylammonium bromide (DTAB) are described. The sensor was based on the use of DTA-tetraphenylborate ion association complex as an electroactive material in screen-printed electrode with dioctylsebacate (DOS) as a solvent mediator. In aqueous solution of pH 3, the sensor displayed a stable response for six months with reproducible potential and linear response for surfactant over the concentration range 1.20 × 10(-2) -5.6 × 10(-7) mol L(-1) at 25 °C with Nernstian slope of 55.95 ± 0.58 mV decade(-1) for detection limit of 6.8 x 10(-6) mol L(-1) . The response time was 6-10 s. The selectivity coefficients indicate excellent selectivity for DTAB over many common cations (e.g. Mg(2+), Na(+), K+, Co(2+), Ni(2+), Ca(2+), Cl(-), I(-), SO(4)(-2) and cetylpyridinium chloride (CPC). The sensor was used successfully for the determining of DTAB in pure form and water samples with average recoveries of 99.98, 98.78, and 99.99%.

Septonex-tetraphenylborate screen-printed ion selective electrode for the potentiometric determination of Septonex in pharmaceutical preparations.

A screen-printed electrode (SPE) was fabricated for the determination of 1-(ethoxycarbonyl)pentadecyltrimethylammonium bromide (Septonex) based on the use of Septonex-tetraphenylborate as the electroactive substance, and o-nitrophenyloctylether (o-NPOE) as the plasticizing agent. The electrode passes a near-Nernstian cationic slope of 59.33 ± 0.85 mV from activity between pH values of 2 to 9 with a lower detection limit of 9×10(-7) M and response time of about 5 s and exhibits an adequate shelf-life of 6 months. The method was applied for the determination of Septonex in pharmaceutical preparations. A percentage recovery of 99.88% was obtained with RSD=1.24%. The electrode was successfully applied in the determination of Septonex in laboratory-prepared samples by direct potentiometric, calibration curve and standard addition methods. Potentiometric titration of Septonex with sodium tetraphenylborate and phosphotungstic acid as a titrant was monitored with the modified screen-printed electrode as an end-point indicator electrode. Selectivity coefficients for Septonex relative to a number of potential interfering substances were determined. The sensor was highly selective for Septonex over a large number of compounds. Selectivity coefficient data for some common ions show negligible interference; however, cetyltrimethylammonium bromide and iodide ions interfere significantly. The analytical usefulness of the proposed electrode was evaluated by its application in the determination of Septonex in laboratory-prepared pharmaceutical samples with satisfactory results. The results obtained with the fabricated sensor are comparable with those obtained by the British Pharmacopeia method.

Potentiometric determination of cetylpyridinium chloride using a new type of screen-printed ion selective electrodes.

A new type of screen-printed ion-selective electrode for the determination of cetylpyridinium chloride (CPC) is presented. These new electrodes involve in situ, modified and unmodified screen-printed ion-selective electrodes for the determination of CPC. The screen-printed electrodes (SPEs) show a stable, near-Nernstian response for 1 x 10(-2) to 1 x 10(-6) M CPC at 25 degrees C over the pH range 2-8 with cationic slope 60.66+/-1.10. The lower detection limit is found to be 8 x 10(-7) M and response time of about 3s and exhibit adequate shelf-life (6 months). The fabricated electrodes can be also successfully used in the potentiometric titration of CPC with sodium tetraphenylborate (NaTPB). The analytical performances of the SPEs are compared with those for carbon paste electrode (CPE) and polyvinyl chloride (PVC) electrodes. The method is applied for pharmaceutical preparations with a percentage recovery of 99.60% and R.S.D.=0.53. The frequently used CPC of analytical and technical grade as well as different water samples has been successfully titrated and the results obtained agreed with those obtained with commercial electrode and standard two-phase titration method. The sensitivity of the proposed method is comparable with the official method and ability of field measurements.