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A rapid, selective and sensitive method for the quantification of Pd (II) using spectrophotometric technique associated with Z-N'-(benzo(d) thiazol-2-yl)-N,N-dimethylformimidamide BTDF as new chelating agent is described. Yellow colored complex of Pd (II) with BTDF is formed in Britton-Robinson universal buffer of pH 9 and extracted with chloroform. The formed complex clearly illustrate an absorption at ∼384 nm and follw Beer’s law in the range of concentration between 0.5–18.0 µg ml−1 of Pd (II) with absorbance of 3.62 × 104 L mol-1 cm-1 and limit of detection(LOD) of Pd (II) 0.07 µg ml−1. The effects of different experimental parameters have been established by study the optimum conditions for the extraction and quantification of palladium ion. Density functional theory (DFT) havealso been employed to computethe influence of the cation on theoretical parameters of Pd2+ complexes. The effect of donating centers was investigated theoretically which prove that Pd2+ favor coordinated with two molecules of Z-N'-(benzo(d)thiazol-2-yl)-N,N-dimethylformimidamide through two nitrogen atoms.The performance of the examined method was estimated to detect the impact of current method over the presented methods in the literature without interference effect of cations and anions. The examined method has successfully demonstrated the quantification of Pd(II) in natural and spiked water samples.

Two different techniques are developed for the determination of clopidogrel in pharmaceutical preparations. HPLC method has been developed where chromatographic analysis is performed on Nova-Pak(superscript ®) C18 column (3.9 mm×150 mm, 5 μm) with an ammonium formate buffer adjusted with formic acid to pH 4.0, acetonitrile (40:60, v/v) as mobile phase, and detection at 225 nm. Good linearity (0.9993, r), accuracy (≥99.20%) and precision (≤0.6 RSD) were obtained. Potentiometric measurments are based on tetrakis (p-chlorophenyl) borate-clopidogrel ion-pair as an electroactive material incorporating a plasticized PVC membrane with o-nitrophenyl octyl ether or dioctyl phthalate. The sensor is conditioned for at least two days in 0.1 M drug solution before use. It exhibits fast and stable Nernstian response for clopidogrel over the concentration range of 1.0×10^(-5)~1.0×10^(-2) M and pH range of 1.5-4.0. Results with an average recovery of 100.6% and a mean standard deviation of 0.86% of the nominal were obtained. The sensor shows reasonable selectivity towards clopidogrel hydrogen sulphate in presence of many cations. No significant interferences are caused by drug excipients and diluents.

This study involves the preparation and investigation of a novel and highly selective poly(vinyl chloride)-based membrane of 2-((5-(2-hydroxy-3-methoxybenzylideneamino)-2H-1,2,4-triazol-3-ylimino)methyl)-6-methoxyphenol Schiff base ligand (HMBT), which is a neutral ionophore with sodium tetraphenyl borate (STB) in the form of an excluder and o-nitrophenyloctyl ether (o-NPOE) in the form of solvent mediators (plasticizing) as a Ni(II)-selective electrode. The observation of optimal performance was done wherein the membrane was shown to have the HMBT–PVC–NPOE-STB composition of 4:32:63:1.It worked effectively across a broad range of concentration (1.0 × 10−8 to 1.0 × 10−2 mol L−1). Meanwhile, the Nernstian slope was recorded as 29.3 mV per decade of activity between pH 3.0 and 8.0. The response time of this electrode was fast at 11 s which was used for a span of 100 days with sound reproducibility. According to the selectivity coefficients for trivalent, divalent, and monovalent cations, excellent selectivity was indicated for Ni(II) ions across a large number of citations, whereas no interference was caused by anions like PO43-, SO42− and Cl−. The proposed method in this study was applied successfully to determine Ni(II) content in different samples of water, obtaining suitable recoveries. Additionally, the probed sensor is utilized as indicator electrode when considering Ni2+ ion potentiometric titration against EDTA. In addition, the chelate’s geometry and structure of the complex formed between Ni2+ ions and HMBT, abbreviated as HMBT-Ni2, was evaluated by separating the solid product. Complex structure was confirmed based on alternative analytical and spectral methods to be structured in the bimetallic form with the formula [Ni2(HMBT)(H2O)2 Cl2]. The diamagnetic nature of the complex, which was concluded from the room temperature magnetic moment measurement combined with the UV-Vis measurement, suggested the square planar geometry around the Ni centers.

A simple methods have been developed for determination of Cu(II) ions in aqueous solutions. The spectrophotometric method relied mainly on the reaction between Cu(II) ions and the azo dye ligand named N-diaminomethylene-4-(2,4-dihydroxy-phenylazo)-benzenesulfonamide (H2L) at pH 10.0. The influence of parameters such as concentration, pH and reaction time were inspected. A linear relationship (R2 = 0.9992) between absorbance and the concentration of Cu(II) was obtained at the maximum absorption peak of 474 nm within 1.6–9.6 × 10−6 mol L−1 concentration range. The limit of detection for Cu(II) ion and limit of quantitation were 1.1 × 10−7 mol L−1 and 3.7 × 10−7 mol L−1, respectively. The potentiometric method is based on a novel poly(vinyl chloride) membrane, containing the synthesized azo dye as an ionophore, was used to developed a Cu(II)- selective sensor. This newly developed sensor revealed a Nernstian response over Cu2+ ion in a concentration range 1.0 × 10−6–1.0 × 10−2 mol L−1 with cationic slopes of 29.5 ± 0.2 mV decade−1 and detection limits of 3.0 × 10−6 mol L−1 copper(II) for o-nitrophenyl-octyl ether (o-NPOE) based membrane sensor. The electrode showed good discrimination toward Cu2+ ions with respect to most common cations. The advantages of the proposed methods are their simplicity, selectivity, and high sensitivity. In addition, the sensor has been used as indicator electrode in the potentiometric titration of Cu2+ ion against EDTA. The structure and geometry of the complex formed between Cu(II) and H2L ligand was identified via isolation of the solid complex; Co(II) an Ni(II) complexes were synthesized as well. The geometrical structure around the metal centers were proved to be square planar for Cu(II) complex and tetrahedral for Co(II) an Ni(II) complexes.

Three neurotransmitter sensors for dopamine, serotonin, and epinephrine have been developed. Potentiometric sensors for serotonin and epinephrine are novel and first to be introduced. The neurotransmitter potentiometric sensors are based on using dibenzo-30-crown-10 (DB30C10), dibenzo-24-crown-8 (DB24C8), and dibenzo-18-crown-6 (DB18C6) as ionophores and neutral carriers incorporating in poly(vinyl chloride) matrix membrane plasticized with o-nitrophenyl octyl ether. Sensors based on dibenzo-30-crown-10 show good responses for the dopamine, serotonin, and epinephrine (Type I–III, respectively) with a cationic slope of 57.9 mV decade−1 and detection limit of 4.0×10−5 mol L−1 dopamine, cationic slope of 55.9 mV decade−1 and detection limit of 4.0×10−5 mol L−1 serotonin, and cationic slope of 54.4 mV decade−1 and detection limit of 2.0×10−5 mol L−1 epinephrine. The sensors based on DB24C8 and DB18C6 (Types IV–IX) show poor responses in terms of calibration range and slope. The effect of the interferents on the response of the sensors reveals a high selectivity for the neurotransmitters over many inorganic cations, ascorbic and uric acids. The useful pH range for the three sensors is 3–7, the response time is fast (11 s), and the life span is long (2.5 months). Sensors (Types I and III) are successfully used for the quantification of dopamine and adrenaline in pharmaceutical preparations.

A new and rapid potentiometric method to quantify aluminum ions concentration was developed. The method involves the development of an aluminum ion sensor with a membrane consists of diethyl (2-azobenzoic acid) malonate (DAM) as a novel ionophore in poly (vinyl chloride) matrix membrane plasticized with orthonitrophenyl-octyl ether or dioctylphthalate. The structure of the synthesized ionophore (DAM) was identified using Fourier transform infrared, 1H Nuclear magnetic resonance, and elemental analysis. The proposed electrode reveals a Nernstian response over Al3+ ion in a concentration range $1\times 10^{\mathrm {-7}}$ – $1\times 10^{\mathrm {-2}}$ mol $\text{L}^{\mathrm {-1}}$ with the cationic slopes of 19.6 ± 0.3 and 19.3 ± 0.2 mV decade $^{\mathrm {-1}}$ , and the limits of detection $5 \times 10^{\mathrm {-8}}$ and $7 \times 10^{\mathrm {-8}}$ mol $\text{L}^{\mathrm {-1}}$ aluminum(III) for orthonitrophenyl-octyl ether and dioctylphthalate-based membrane sensors, respectively. The electrodes showed good discrimination toward Al3+ ion in the presence of the most common cations. The electrodes show response in a short time (10 s) for the entire concentration range and used for 11 weeks without significant variation in potentials. To evaluate the application of the investigated electrodes was used to determine Al3+ ion at different collected samples from environmental sources. In addition, these sensors have been used as indicator electrodes in the potentiometric titration of Al3+ ion against Ethylenediaminetetraacetic acid.

The characteristics, performance and application of ion-selective electrodes for bromate ion based on rhodamine B and tetrahexyl ammonium bromide as electrode-active substances are described for the first time. These electrodes respond with sensitivities of (58.0±1.0) and (61.0±2.0) mV decade−1 over the range 1.0×10−8–1.0×10−2 mol l−1 at pH 4–9 and 4–8 and a detection limit of 6.0×10−8 and 4.0×10−8 mol l−1 for rhodamine B and tetrahexyl ammonium bromide sensors, respectively. The electrodes are easily constructed at a relatively low cost, have a fast response time and can be used for a period of 3 months without any considerable divergence in potential. The proposed sensors displayed good selectivity for bromate ion in the presence of several substances and inorganic anions. Sensors were used for the direct assay of bromate ion in drinking water samples.

A new and rapid potentiometric method for determination of flucloxacillin is developed. The method involves development of a flucloxacillin sensor with a membrane consisting of Aliquat 336S-flucloxacillin as an electroactive material in poly vinyl chloride matrix membrane plasticized with orthonitrophenyl-octylether or dioctylphthalate. The sensor shows fast, stable and reproducible response over the concentration range of 1.0 × 10 −5 –1.0 × 10 −2 M flucloxacillin with anionic slopes of 60.7 ± 0.3 and 61.2 ± 0.2 and pH ranges of 6–11 and 7–11 for o -nitrophenyloctylether ( o -NPOE) and dioctylphthalate (DOP) plasticized based membrane sensors, respectively. The response time of the sensor is stable and fast (7 s). The sensor exhibits high selectivity towards flucloxacillin in presence of amoxicillin, ampicillin, dicluxacillin, pencillin, many anions and 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. Results with average recoveries of 99.6% and 99.7% and mean standard deviations of ±1.2% and ±1.5% for o -NPOE and DOP plasticized based membrane sensors, respectively, of the nominal are obtained which compare fairly well with data obtained using the British Pharmacopoeia method.