The acid-base properties of Allura Red AC and Ponceau 4R were investigated. The ionization consta... more The acid-base properties of Allura Red AC and Ponceau 4R were investigated. The ionization constants of the respective azo dyes functional groups were determined. The spectrophotometric characteristics of the Allura Red AC and Ponceau 4R in different solvents were calculated. The most probable protonation/deprotonation schemes were theoretically determined for Allura Red AC and Ponceau 4R using DFT calculations.
In thiswork,we investigated the chemiluminescence generated fromthe reaction of bis(2,4,6-trichlo... more In thiswork,we investigated the chemiluminescence generated fromthe reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO), hydrogen peroxide and 1,4- dihydroxyanthraquinone (quinizarin). Furthermore, the effect of solvent and concentrations of necessary reagents, TCPO, sodium salicylate, hydrogen peroxide and quinizarin on the luminescence efficiency of the system were studied. Under the optimal condition the suitable values of concentrations of the TCPO:H2O2:SS:Qz systemwere of 5.50 × 10-4, 8.34 × 10-2, 4.27 × 10-6 and 7.51 × 10-4M, respectively.
During the past decade, the analysis of trace metal ions has become a real challenge due to the s... more During the past decade, the analysis of trace metal ions has become a real challenge due to the specificity, accuracy and sensitivity required by ever more stringent regulations. 1-3 The toxicological effects of metal ions, such as aluminum, on living system, especially on human beings, are now well known. Several recent epidemiological studies investigated the correlation between the uptake of aluminum ions, mostly from drinking water, and the Alzheimer's and Parkinson's diseases, as well as dialysis diseases. 4-8 Because aluminum is still used as a flocculating agent in potable water treatment units, there is an increasing need for aluminum monitoring in treated and raw water samples. 9-11 Aluminum monitoring and speciation is also of vital importance in the aluminum industry as a source for light metal materials and light alloys 12 and in ecological impacts of aluminum. 13,14 Aluminum determination in water samples is generally carried out with classical techniques, such as atomic absorption or emission spectrometry. However, these methods are very time and money consuming, and do not permit real-time or even onsite determinations. Ion-selective electrodes based on solvent polymeric membranes with the incorporation of specific ion carriers have been shown to be very useful tools for metal-ion analyses in different samples, 15-18 due to their ease of preparation, simple operation, reasonable selectivity, relatively fast response and low cost. Despite the urgent need for Al 3+ ion-selective electrodes for fast and accurate monitoring of aluminum in different industrial, medicinal and environmental samples, there are only limited reports in the literature on Al 3+ sensors to directly determine the aluminum concentration. 19-22 Thioxanthone (TX) derivatives have been shown to possess very useful medicinal properties. 23,24 They have been introduced in such processes as surface coating, printing inks, photoresistors and microelectronics. 25 Several TX derivatives have been synthesized and examined in terms of their efficiency as photoinitiators. 26-28 However, to the best of our knowledge, there is no previous report on the use of TX derivatives as ion carriers in such analytical applications as ion transport through liquid membranes and the preparation of ion-selective electrodes. Very recently, we have reported on new PVC-based ionselective electrodes for some trivalent metal ions, including Ce 3+ , 29 Fe 3+ , 31 and Yb 3+. 32 In this work we found that the recently synthesized thioxanthone derivatives 1-hydroxythioxanthone (TX1), 1,3-dihydroxy-thioxanthone (TX2), 1,4dihydroxy-thioxanthone (TX3), 1,4-dihydroxy-3-methylthioxanthone (TX4) and 1-hydroxy-3-methyl-thioxanthone (TX5) (Fig. 1) can form highly selective 2:1 (TX: metal ion) complexes with Al 3+ ion in a methanol solution. Thus, due to their water insolubility and high tendency for Al 3+ complexation, we examined thioxanthones TX1-TX5 as neutral ionophores for the preparation of PVC-based membrane sensors for Al 3+. The membrane based on TX5 resulted in the best response characteristics for aluminum ion. Experimental Reagents Reagent-grade nitrophenyl octyl ether (NPOE), dibutyl phthalate (DBP), acetophenone (AP), oleic acid (OA), sodium tetraphenylborate (STPB), high relative molecular weight PVC 301
In the current study, the interaction between L‐dopa and bovine serum albumin (BSA) as well as ca... more In the current study, the interaction between L‐dopa and bovine serum albumin (BSA) as well as catechol and BSA is investigated separately. In order to achieve the optimum values for encapsulated efficiency (EE), the content of crosslinker/BSA, organic/aqueous phase, drug/BSA, stirring rate, and pH were closely studied taking the advantage of Taguchi method. Particle characterization was carried out using transmission electron microscopy and dynamic light scattering techniques. The most appropriate catechol and L‐dopa nanoparticles in the size range of 100 nm and 65 nm, respectively, and at optimized conditions of drug/BSA = 0.1, pH = 7.4, crosslinker/BSA = 0.084, organic/aqueous phase = 4 and stirring rate 400 rpm were obtained. The most favorable EE (encapsulation efficiency) and LC (loading capacity) for L‐dopa and catechol was estimated to be 88.1% and 83.6%, respectively, and the calculated LC% was achieved 93.4% and 89.7% for L‐dopa and catechol, respectively. The chromatograp...
This Study investigated the effect of potassium bromate on the nutritional value of wheat flour p... more This Study investigated the effect of potassium bromate on the nutritional value of wheat flour preserved with potassium bromate. Superb bakers choice wheat flour was used for the study. The wheat was divided into five equal portions thoroughly mixed with varying doses (0mg, 50mg, 100mg, 200mg and 300mg/kg flour) of potassium bromate respectively. Samples were wrapped in black polythene bags to protect them from light and stored for 4 weeks while the nutrient values of the different rations and dough made from them were determined at the onset and then at the end of the study which was four (4) weeks. Results of the study showed that potassium bromate significantly (p< 0.05) reduced the vitamin A content of the treated flour and dough while it significantly (p< 0.05) reduced the iron level of the treated dough only. The results of the study showed that potassium bromate deteriorates the nutritional value of both flour and dough. 2011 Trade Science Inc. INDIA Regular Paper
Journal of Polymer Science Part A: Polymer Chemistry, 2019
ABSTRACTDespite the outstanding properties of hyperbranched polyglycerols such as biocompatibilit... more ABSTRACTDespite the outstanding properties of hyperbranched polyglycerols such as biocompatibility and multifunctionality, enough attention has not been paid to the synthesis of their functional copolymers. This problem has limited the structural diversity of hyperbranched polyglycerols and hampers further developments and their practical usage. In this work, butyrolactone segments were incorporated into the backbone of polyglycerols by one‐pot ring‐opening copolymerization of a mixture of glycidol and γ‐butyrolactone in the presence of tin(II) 2‐ethylhexanoate. Poly(glycerol‐oligoγ‐butyrolactone)s were then crosslinked by 2,5‐thiophenediylbisboronic acid to obtain polymeric nanonetworks with 140 nm average size. Afterwards, the gold electrode was modified by the polymeric nano‐networks, and it was used for the determination of glucose, glycated hemoglobin, and Escherichia coli in phosphate buffer solution (pH = 9.0) through cyclic voltammetry and impedance spectroscopic. Taking adv...
In this work, we fabricated a new renewable syringe carbon paste electrode (SCPE) equipped with a... more In this work, we fabricated a new renewable syringe carbon paste electrode (SCPE) equipped with a motor rotary cutting blade and used for voltammetric determination of dipyridamole (DIP) in aqueous solution, at room temperature. The cutter rotates by a small electrical motor and easily renews the surface of the carbon paste electrode by removing the spotty surface. Electrochemical performance of the constructed electrode was investigated with cyclic voltammetry (CV) and compared to some other previously reported works. The new sensor showed several advantages such as excellent repeatability, high stability, good sensitivity and easily surface renewable. The results indicated that the presence of methyltrioctyl ammonium chloride (MTOAC) could remarkably enhance the oxidation of DIP due to feasible electrical conductivity properties in a phosphate buffer solution. At optimum conditions for the new syringe CPE, the square wave voltammetry (SWV) was used to measure the concentration of DIP in a linear range of 0.08-30.0 µM and a detection limit of 0.02 µM was obtained after 100 s of accumulation time. The sensor was then tested for the simple, rapid and sensitive electrochemical determination of DIP in real samples such as pharmaceutical formulations.
Abstract Here, we introduce a new electrode comprising silver decorated multiwall carbon nanotube... more Abstract Here, we introduce a new electrode comprising silver decorated multiwall carbon nanotube (Ag-MWCNT) as the sensing element for voltammetric investigation of anticancer drug Epirubicin (EP) in human whole blood, urine and injection. Field emission scanning electron microscopy (FE-SEM), TEM, EDX and XRD methods were used to study the surface structure and topography of the modified electrode. We used electrochemical impedance spectroscopy (EIS) as a powerful tool to analyze the electrochemical properties of the new electrode. This modified electrode was applied for investigation of EP by cyclic voltammetry (CV) and square wave voltammetry (SWV) in an acetate buffer solution as a suitable supporting electrolyte (pH 1.5 - 6.8). The CV of EP in the potential range of -1.0 to 1.0 V showed reversible redox peaks that were dependent on pH. We optimized the conditions needed for practical application of the new electrochemical sensor, for which the redox peak current at pH 4.7 was linearly proportional to the concentration of EP in the range of 0.003 - 0.25 μM with a detection limit of 1.0 × 10-3 μM (RSD
Abstract Here, we report the synthesis of 1,3,5-Trithiane-Ag-nanoparticles decorated polyaniline ... more Abstract Here, we report the synthesis of 1,3,5-Trithiane-Ag-nanoparticles decorated polyaniline nanofibers (TAN-AgNP-PANF) and describe its benefit in the sensing element of an electrochemical sensor for simultaneous detection of Adenine (A) and Guanine (G). We characterized the electrode composition with field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and Fourier-transform infrared spectroscopy (FT-IR). The electrocatalytic oxidation of A and G on the electrode sensor was explored by differential pulse voltammetry (DPV) and cyclic voltammetry (CV). This sensor shows separate and well-defined peaks for A and G, by which one can determine these biological bases individually or simultaneously. A linear relationship is figured out between the peak current and the analytes' concentrations on range 1.0 to 200 and 0.9 to 140 μM, for simultaneous determination of A and G, with detection limits of 2.8 and 3.0 μM, respectively. Furthermore, individually determination is resulted in two linear concentration ranges of 0.08 to 25.0 and 0.01 to 15.0 μM with detection limits of 24.0 and 0.06 μM for A and G, respectively. The sensor demonstrates a good stability and sufficient selectivity over the amino acids and could be used to quantify of A and G in fish sperm DNA sample successfully.
We are reporting the study of the complexation of a newly synthesized tetera-oxime derivative (2,... more We are reporting the study of the complexation of a newly synthesized tetera-oxime derivative (2,5,10,13-Tetraazatricyclo[12,2,2,2]icosa-1(16),6,8,14,17,19-hexene-3,4,11,12,13-tetraone tetraoxime) with Ag(I) in acetonitrile. Analytical techniques (IR and UV-Vis), conductometry and potentiometry showed that the ligand reacts selectively towards Ag(I) ion. In addition, the stoichiometry of resulted complexes was investigated by studying their GC-Mass spectra. The results revealed that the mole ratios of the reactants in the complexes were 2:1 and 1:1 (metal:ligand). The stepwise formation constants (K 1 and K 2) were evaluated (3.2×10 8 and 4.3×10 7 , respectively) by using a computerized non-linear curve-fitting program.
A dichromate-selective PVC-membrane electrode based on Quinaldine Red (an acridinium derivative) ... more A dichromate-selective PVC-membrane electrode based on Quinaldine Red (an acridinium derivative) is described. The electrode exhibits rapid (< 30 s) and linear response to the activity of Cr(VI) anions in the range of 5.2´10-6-1.0´10-1 M dichromate with the limit of detection 2.5´10-6 M of Cr 2 O 7 2-. The sensor is used as an indicator electrode in potentiometric determination of Cr(VI) anions and is also suitable for end-point indication in the titrations of proper metal ions with dichromate under laboratory conditions. The proposed electrode has been applied to the direct potentiometric determination of Cr(VI) anions in water samples with satisfactory results.
A novel optical sensor that is highly selective to Hg 2+ ions is described. This is based on the ... more A novel optical sensor that is highly selective to Hg 2+ ions is described. This is based on the use of 4-phenyl-2,6-bis(2,3,5,6-tetrahydrobenzo[b][1,4,7]trioxononin-9-yl)pyrylium perchlorate as an ionic carrier in a plasticized poly(vinyl chloride) membrane. The sensing membrane is capable of determining mercury(II) with a high selectivity over a wide dynamic range between 2.95 × 10 −10 and 3.20 × 10 −3 M at pH 5.0 with a lower detection limit of 1.01 × 10 −10 M. Validation of the assay method reveals excellent performance characteristics, including long life span, good selectivity for Hg 2+ ions over a wide variety of other metal ions, long-term response stability, and high reproducibility. Applications for direct determination of mercury in samples including dental amalgam, shaft water, and fountain give results with good correlation with data obtained using cold vapor atomic absorption spectrometry.
A sensor membrane based on 1-hydroxy-3,4-dimethyl-9H-thioxanthen-9-one has been developed for the... more A sensor membrane based on 1-hydroxy-3,4-dimethyl-9H-thioxanthen-9-one has been developed for the determination of copper(II) ions that displays excellent performance. The sensing membrane is capable of determining copper(II) with an outstanding high selectivity over a dynamic range between 1.6 × 10 −7 and 1.3 × 10 −2 M with a limit of detection of 4.0 × 10 −7 M (25.1 ppb). The sensor shows a fast response time (<1 min) and the membrane can be used for more than 6 months without observing any major deviation. The optode revealed very good selectivity with respect to many cations including alkali, alkaline earth, transition and heavy metal ions. The proposed sensor could be used at a neutral pH of 7.5. It was applied to determination of copper in black tea, and in water. The optode was also used in photometric titration of the copper(II) ion with EDTA.
... This paper presents the development and construction of a sensitive new optical sensor that i... more ... This paper presents the development and construction of a sensitive new optical sensor that is highly selective to ... There is currently great interest in the design of sensitive and discriminatingoptical sensors as an emerging ... Mercury is one of the heavy metals, which is highly toxic ...
We report on newly synthesized Ag(I)-filled multiwall carbon nanotubes as a potential sensing ele... more We report on newly synthesized Ag(I)-filled multiwall carbon nanotubes as a potential sensing element in ion-selective carbon paste electrodes for the determination of free cyanide in aqueous solution. The electrode was obtained by entrapping the silver-filled nanotubes into a carbon paste and displays a Nernstian response with a slope of 59.8±0.3 mV decade −1 , a very wide linear range (from 21.0 nM to 0.1 M of cyanide), a lower detection limit of 13.0 nM, and a response time of <2 min. The operational lifetime is up to 3 months without significant deviation in normal function.
A highly sensitive and selective optical membrane sensor was prepared for the determination of ul... more A highly sensitive and selective optical membrane sensor was prepared for the determination of ultra trace amount of Ni 2+ ions. The plasticized PVC membrane incorporating dibuthylphthalate and 2-amino-1-cyclopentene-dithiocarboxylic acid (ACDA) as a chromoionophore works on the basis of a cation-exchange mechanism and shows a significant absorbance signal change on exposure to acidic solution containing nickel(II) ion. The sensor displays a calibration response for Ni 2+ ion over a wide concentration range of 3.1 Â 10 À8-8.0 Â 10 À3 M, and a response time of 3 min. In addition to high stability, reproducibility and relatively long working lifetime, the sensor possesses good selectivity for nickel(II) ion over several common diverse ions. The sensor was successfully applied to determine the traces of Ni 2+ ion in some water samples.
Bromopyrogallol red (BPR) pH-indicator was incorporated into a sol-gel silica matrix and used for... more Bromopyrogallol red (BPR) pH-indicator was incorporated into a sol-gel silica matrix and used for sensing pH as a solid indicator. Entrapment of BPR into silica matrix was performed by the acid-catalyzed sol-gel reaction of tetraethylorthosilicate (TEOS) and the BPR indicator. The immobilized BPR shows better behavior than its solvated form in solution. No leaching was observed during the repetitive experiments, indicating that BPR molecules were strongly trapped into the silica matrix. At optimal condition, the sensor responded rapidly to pH changes in a range of 2.33-9.42 with the response time about a minute. The equation A = 0.081 + 0.038 pH with R 2 = 0.992 was obtained by regression of linear portion of the calibration curve plot of the sensor responses at various pH values. This sensor was highly sensitive, quite reversible and had a long lifetime of over 10 months.
The synthesis and structural characterization of a novel generation of crown ethers, 3, 5 and 6 c... more The synthesis and structural characterization of a novel generation of crown ethers, 3, 5 and 6 containing pyrilium, thiopyrilium, and pyridinium subunits, respectively, are reported. The crown ether unit is potentially capable of forming host-guest complexes with inorganic and organic cations, while the heteroaromatic cationic unit is suitable to bind with anions. A variety of physicochemical methods including electrospray mass spectrometry, UV-vis spectroscopy, solution and solid-phase NMR, and X-ray crystallography were applied for structural characterization of the new crown ether derivatives. The (1)H and (13)C NMR studies indicate rapid rotation of the B9C3 unit about the C-C bond that connects the two units to each other. Single crystals for 3, 4, and 5 were successfully obtained, and their X-ray crystal structures were resolved. The perchlorate anion in 3 (orthorhombic, space group P2(1)2(1)2(1)) and 5 (orthorhombic, space group P2(1)) is far from O(+) and close to S(+). The solid-phase structure of 3 and 5 show small deviation from planarity for the four aromatic rings, whereas two of the aromatic rings in 4 are out of heteroaromatic ring. Spectrophotometric studies in methanol solution revealed that the ligand 3 can be successfully applied to selective amino acid recognition.
The acid-base properties of Allura Red AC and Ponceau 4R were investigated. The ionization consta... more The acid-base properties of Allura Red AC and Ponceau 4R were investigated. The ionization constants of the respective azo dyes functional groups were determined. The spectrophotometric characteristics of the Allura Red AC and Ponceau 4R in different solvents were calculated. The most probable protonation/deprotonation schemes were theoretically determined for Allura Red AC and Ponceau 4R using DFT calculations.
In thiswork,we investigated the chemiluminescence generated fromthe reaction of bis(2,4,6-trichlo... more In thiswork,we investigated the chemiluminescence generated fromthe reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO), hydrogen peroxide and 1,4- dihydroxyanthraquinone (quinizarin). Furthermore, the effect of solvent and concentrations of necessary reagents, TCPO, sodium salicylate, hydrogen peroxide and quinizarin on the luminescence efficiency of the system were studied. Under the optimal condition the suitable values of concentrations of the TCPO:H2O2:SS:Qz systemwere of 5.50 × 10-4, 8.34 × 10-2, 4.27 × 10-6 and 7.51 × 10-4M, respectively.
During the past decade, the analysis of trace metal ions has become a real challenge due to the s... more During the past decade, the analysis of trace metal ions has become a real challenge due to the specificity, accuracy and sensitivity required by ever more stringent regulations. 1-3 The toxicological effects of metal ions, such as aluminum, on living system, especially on human beings, are now well known. Several recent epidemiological studies investigated the correlation between the uptake of aluminum ions, mostly from drinking water, and the Alzheimer's and Parkinson's diseases, as well as dialysis diseases. 4-8 Because aluminum is still used as a flocculating agent in potable water treatment units, there is an increasing need for aluminum monitoring in treated and raw water samples. 9-11 Aluminum monitoring and speciation is also of vital importance in the aluminum industry as a source for light metal materials and light alloys 12 and in ecological impacts of aluminum. 13,14 Aluminum determination in water samples is generally carried out with classical techniques, such as atomic absorption or emission spectrometry. However, these methods are very time and money consuming, and do not permit real-time or even onsite determinations. Ion-selective electrodes based on solvent polymeric membranes with the incorporation of specific ion carriers have been shown to be very useful tools for metal-ion analyses in different samples, 15-18 due to their ease of preparation, simple operation, reasonable selectivity, relatively fast response and low cost. Despite the urgent need for Al 3+ ion-selective electrodes for fast and accurate monitoring of aluminum in different industrial, medicinal and environmental samples, there are only limited reports in the literature on Al 3+ sensors to directly determine the aluminum concentration. 19-22 Thioxanthone (TX) derivatives have been shown to possess very useful medicinal properties. 23,24 They have been introduced in such processes as surface coating, printing inks, photoresistors and microelectronics. 25 Several TX derivatives have been synthesized and examined in terms of their efficiency as photoinitiators. 26-28 However, to the best of our knowledge, there is no previous report on the use of TX derivatives as ion carriers in such analytical applications as ion transport through liquid membranes and the preparation of ion-selective electrodes. Very recently, we have reported on new PVC-based ionselective electrodes for some trivalent metal ions, including Ce 3+ , 29 Fe 3+ , 31 and Yb 3+. 32 In this work we found that the recently synthesized thioxanthone derivatives 1-hydroxythioxanthone (TX1), 1,3-dihydroxy-thioxanthone (TX2), 1,4dihydroxy-thioxanthone (TX3), 1,4-dihydroxy-3-methylthioxanthone (TX4) and 1-hydroxy-3-methyl-thioxanthone (TX5) (Fig. 1) can form highly selective 2:1 (TX: metal ion) complexes with Al 3+ ion in a methanol solution. Thus, due to their water insolubility and high tendency for Al 3+ complexation, we examined thioxanthones TX1-TX5 as neutral ionophores for the preparation of PVC-based membrane sensors for Al 3+. The membrane based on TX5 resulted in the best response characteristics for aluminum ion. Experimental Reagents Reagent-grade nitrophenyl octyl ether (NPOE), dibutyl phthalate (DBP), acetophenone (AP), oleic acid (OA), sodium tetraphenylborate (STPB), high relative molecular weight PVC 301
In the current study, the interaction between L‐dopa and bovine serum albumin (BSA) as well as ca... more In the current study, the interaction between L‐dopa and bovine serum albumin (BSA) as well as catechol and BSA is investigated separately. In order to achieve the optimum values for encapsulated efficiency (EE), the content of crosslinker/BSA, organic/aqueous phase, drug/BSA, stirring rate, and pH were closely studied taking the advantage of Taguchi method. Particle characterization was carried out using transmission electron microscopy and dynamic light scattering techniques. The most appropriate catechol and L‐dopa nanoparticles in the size range of 100 nm and 65 nm, respectively, and at optimized conditions of drug/BSA = 0.1, pH = 7.4, crosslinker/BSA = 0.084, organic/aqueous phase = 4 and stirring rate 400 rpm were obtained. The most favorable EE (encapsulation efficiency) and LC (loading capacity) for L‐dopa and catechol was estimated to be 88.1% and 83.6%, respectively, and the calculated LC% was achieved 93.4% and 89.7% for L‐dopa and catechol, respectively. The chromatograp...
This Study investigated the effect of potassium bromate on the nutritional value of wheat flour p... more This Study investigated the effect of potassium bromate on the nutritional value of wheat flour preserved with potassium bromate. Superb bakers choice wheat flour was used for the study. The wheat was divided into five equal portions thoroughly mixed with varying doses (0mg, 50mg, 100mg, 200mg and 300mg/kg flour) of potassium bromate respectively. Samples were wrapped in black polythene bags to protect them from light and stored for 4 weeks while the nutrient values of the different rations and dough made from them were determined at the onset and then at the end of the study which was four (4) weeks. Results of the study showed that potassium bromate significantly (p< 0.05) reduced the vitamin A content of the treated flour and dough while it significantly (p< 0.05) reduced the iron level of the treated dough only. The results of the study showed that potassium bromate deteriorates the nutritional value of both flour and dough. 2011 Trade Science Inc. INDIA Regular Paper
Journal of Polymer Science Part A: Polymer Chemistry, 2019
ABSTRACTDespite the outstanding properties of hyperbranched polyglycerols such as biocompatibilit... more ABSTRACTDespite the outstanding properties of hyperbranched polyglycerols such as biocompatibility and multifunctionality, enough attention has not been paid to the synthesis of their functional copolymers. This problem has limited the structural diversity of hyperbranched polyglycerols and hampers further developments and their practical usage. In this work, butyrolactone segments were incorporated into the backbone of polyglycerols by one‐pot ring‐opening copolymerization of a mixture of glycidol and γ‐butyrolactone in the presence of tin(II) 2‐ethylhexanoate. Poly(glycerol‐oligoγ‐butyrolactone)s were then crosslinked by 2,5‐thiophenediylbisboronic acid to obtain polymeric nanonetworks with 140 nm average size. Afterwards, the gold electrode was modified by the polymeric nano‐networks, and it was used for the determination of glucose, glycated hemoglobin, and Escherichia coli in phosphate buffer solution (pH = 9.0) through cyclic voltammetry and impedance spectroscopic. Taking adv...
In this work, we fabricated a new renewable syringe carbon paste electrode (SCPE) equipped with a... more In this work, we fabricated a new renewable syringe carbon paste electrode (SCPE) equipped with a motor rotary cutting blade and used for voltammetric determination of dipyridamole (DIP) in aqueous solution, at room temperature. The cutter rotates by a small electrical motor and easily renews the surface of the carbon paste electrode by removing the spotty surface. Electrochemical performance of the constructed electrode was investigated with cyclic voltammetry (CV) and compared to some other previously reported works. The new sensor showed several advantages such as excellent repeatability, high stability, good sensitivity and easily surface renewable. The results indicated that the presence of methyltrioctyl ammonium chloride (MTOAC) could remarkably enhance the oxidation of DIP due to feasible electrical conductivity properties in a phosphate buffer solution. At optimum conditions for the new syringe CPE, the square wave voltammetry (SWV) was used to measure the concentration of DIP in a linear range of 0.08-30.0 µM and a detection limit of 0.02 µM was obtained after 100 s of accumulation time. The sensor was then tested for the simple, rapid and sensitive electrochemical determination of DIP in real samples such as pharmaceutical formulations.
Abstract Here, we introduce a new electrode comprising silver decorated multiwall carbon nanotube... more Abstract Here, we introduce a new electrode comprising silver decorated multiwall carbon nanotube (Ag-MWCNT) as the sensing element for voltammetric investigation of anticancer drug Epirubicin (EP) in human whole blood, urine and injection. Field emission scanning electron microscopy (FE-SEM), TEM, EDX and XRD methods were used to study the surface structure and topography of the modified electrode. We used electrochemical impedance spectroscopy (EIS) as a powerful tool to analyze the electrochemical properties of the new electrode. This modified electrode was applied for investigation of EP by cyclic voltammetry (CV) and square wave voltammetry (SWV) in an acetate buffer solution as a suitable supporting electrolyte (pH 1.5 - 6.8). The CV of EP in the potential range of -1.0 to 1.0 V showed reversible redox peaks that were dependent on pH. We optimized the conditions needed for practical application of the new electrochemical sensor, for which the redox peak current at pH 4.7 was linearly proportional to the concentration of EP in the range of 0.003 - 0.25 μM with a detection limit of 1.0 × 10-3 μM (RSD
Abstract Here, we report the synthesis of 1,3,5-Trithiane-Ag-nanoparticles decorated polyaniline ... more Abstract Here, we report the synthesis of 1,3,5-Trithiane-Ag-nanoparticles decorated polyaniline nanofibers (TAN-AgNP-PANF) and describe its benefit in the sensing element of an electrochemical sensor for simultaneous detection of Adenine (A) and Guanine (G). We characterized the electrode composition with field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and Fourier-transform infrared spectroscopy (FT-IR). The electrocatalytic oxidation of A and G on the electrode sensor was explored by differential pulse voltammetry (DPV) and cyclic voltammetry (CV). This sensor shows separate and well-defined peaks for A and G, by which one can determine these biological bases individually or simultaneously. A linear relationship is figured out between the peak current and the analytes' concentrations on range 1.0 to 200 and 0.9 to 140 μM, for simultaneous determination of A and G, with detection limits of 2.8 and 3.0 μM, respectively. Furthermore, individually determination is resulted in two linear concentration ranges of 0.08 to 25.0 and 0.01 to 15.0 μM with detection limits of 24.0 and 0.06 μM for A and G, respectively. The sensor demonstrates a good stability and sufficient selectivity over the amino acids and could be used to quantify of A and G in fish sperm DNA sample successfully.
We are reporting the study of the complexation of a newly synthesized tetera-oxime derivative (2,... more We are reporting the study of the complexation of a newly synthesized tetera-oxime derivative (2,5,10,13-Tetraazatricyclo[12,2,2,2]icosa-1(16),6,8,14,17,19-hexene-3,4,11,12,13-tetraone tetraoxime) with Ag(I) in acetonitrile. Analytical techniques (IR and UV-Vis), conductometry and potentiometry showed that the ligand reacts selectively towards Ag(I) ion. In addition, the stoichiometry of resulted complexes was investigated by studying their GC-Mass spectra. The results revealed that the mole ratios of the reactants in the complexes were 2:1 and 1:1 (metal:ligand). The stepwise formation constants (K 1 and K 2) were evaluated (3.2×10 8 and 4.3×10 7 , respectively) by using a computerized non-linear curve-fitting program.
A dichromate-selective PVC-membrane electrode based on Quinaldine Red (an acridinium derivative) ... more A dichromate-selective PVC-membrane electrode based on Quinaldine Red (an acridinium derivative) is described. The electrode exhibits rapid (< 30 s) and linear response to the activity of Cr(VI) anions in the range of 5.2´10-6-1.0´10-1 M dichromate with the limit of detection 2.5´10-6 M of Cr 2 O 7 2-. The sensor is used as an indicator electrode in potentiometric determination of Cr(VI) anions and is also suitable for end-point indication in the titrations of proper metal ions with dichromate under laboratory conditions. The proposed electrode has been applied to the direct potentiometric determination of Cr(VI) anions in water samples with satisfactory results.
A novel optical sensor that is highly selective to Hg 2+ ions is described. This is based on the ... more A novel optical sensor that is highly selective to Hg 2+ ions is described. This is based on the use of 4-phenyl-2,6-bis(2,3,5,6-tetrahydrobenzo[b][1,4,7]trioxononin-9-yl)pyrylium perchlorate as an ionic carrier in a plasticized poly(vinyl chloride) membrane. The sensing membrane is capable of determining mercury(II) with a high selectivity over a wide dynamic range between 2.95 × 10 −10 and 3.20 × 10 −3 M at pH 5.0 with a lower detection limit of 1.01 × 10 −10 M. Validation of the assay method reveals excellent performance characteristics, including long life span, good selectivity for Hg 2+ ions over a wide variety of other metal ions, long-term response stability, and high reproducibility. Applications for direct determination of mercury in samples including dental amalgam, shaft water, and fountain give results with good correlation with data obtained using cold vapor atomic absorption spectrometry.
A sensor membrane based on 1-hydroxy-3,4-dimethyl-9H-thioxanthen-9-one has been developed for the... more A sensor membrane based on 1-hydroxy-3,4-dimethyl-9H-thioxanthen-9-one has been developed for the determination of copper(II) ions that displays excellent performance. The sensing membrane is capable of determining copper(II) with an outstanding high selectivity over a dynamic range between 1.6 × 10 −7 and 1.3 × 10 −2 M with a limit of detection of 4.0 × 10 −7 M (25.1 ppb). The sensor shows a fast response time (<1 min) and the membrane can be used for more than 6 months without observing any major deviation. The optode revealed very good selectivity with respect to many cations including alkali, alkaline earth, transition and heavy metal ions. The proposed sensor could be used at a neutral pH of 7.5. It was applied to determination of copper in black tea, and in water. The optode was also used in photometric titration of the copper(II) ion with EDTA.
... This paper presents the development and construction of a sensitive new optical sensor that i... more ... This paper presents the development and construction of a sensitive new optical sensor that is highly selective to ... There is currently great interest in the design of sensitive and discriminatingoptical sensors as an emerging ... Mercury is one of the heavy metals, which is highly toxic ...
We report on newly synthesized Ag(I)-filled multiwall carbon nanotubes as a potential sensing ele... more We report on newly synthesized Ag(I)-filled multiwall carbon nanotubes as a potential sensing element in ion-selective carbon paste electrodes for the determination of free cyanide in aqueous solution. The electrode was obtained by entrapping the silver-filled nanotubes into a carbon paste and displays a Nernstian response with a slope of 59.8±0.3 mV decade −1 , a very wide linear range (from 21.0 nM to 0.1 M of cyanide), a lower detection limit of 13.0 nM, and a response time of <2 min. The operational lifetime is up to 3 months without significant deviation in normal function.
A highly sensitive and selective optical membrane sensor was prepared for the determination of ul... more A highly sensitive and selective optical membrane sensor was prepared for the determination of ultra trace amount of Ni 2+ ions. The plasticized PVC membrane incorporating dibuthylphthalate and 2-amino-1-cyclopentene-dithiocarboxylic acid (ACDA) as a chromoionophore works on the basis of a cation-exchange mechanism and shows a significant absorbance signal change on exposure to acidic solution containing nickel(II) ion. The sensor displays a calibration response for Ni 2+ ion over a wide concentration range of 3.1 Â 10 À8-8.0 Â 10 À3 M, and a response time of 3 min. In addition to high stability, reproducibility and relatively long working lifetime, the sensor possesses good selectivity for nickel(II) ion over several common diverse ions. The sensor was successfully applied to determine the traces of Ni 2+ ion in some water samples.
Bromopyrogallol red (BPR) pH-indicator was incorporated into a sol-gel silica matrix and used for... more Bromopyrogallol red (BPR) pH-indicator was incorporated into a sol-gel silica matrix and used for sensing pH as a solid indicator. Entrapment of BPR into silica matrix was performed by the acid-catalyzed sol-gel reaction of tetraethylorthosilicate (TEOS) and the BPR indicator. The immobilized BPR shows better behavior than its solvated form in solution. No leaching was observed during the repetitive experiments, indicating that BPR molecules were strongly trapped into the silica matrix. At optimal condition, the sensor responded rapidly to pH changes in a range of 2.33-9.42 with the response time about a minute. The equation A = 0.081 + 0.038 pH with R 2 = 0.992 was obtained by regression of linear portion of the calibration curve plot of the sensor responses at various pH values. This sensor was highly sensitive, quite reversible and had a long lifetime of over 10 months.
The synthesis and structural characterization of a novel generation of crown ethers, 3, 5 and 6 c... more The synthesis and structural characterization of a novel generation of crown ethers, 3, 5 and 6 containing pyrilium, thiopyrilium, and pyridinium subunits, respectively, are reported. The crown ether unit is potentially capable of forming host-guest complexes with inorganic and organic cations, while the heteroaromatic cationic unit is suitable to bind with anions. A variety of physicochemical methods including electrospray mass spectrometry, UV-vis spectroscopy, solution and solid-phase NMR, and X-ray crystallography were applied for structural characterization of the new crown ether derivatives. The (1)H and (13)C NMR studies indicate rapid rotation of the B9C3 unit about the C-C bond that connects the two units to each other. Single crystals for 3, 4, and 5 were successfully obtained, and their X-ray crystal structures were resolved. The perchlorate anion in 3 (orthorhombic, space group P2(1)2(1)2(1)) and 5 (orthorhombic, space group P2(1)) is far from O(+) and close to S(+). The solid-phase structure of 3 and 5 show small deviation from planarity for the four aromatic rings, whereas two of the aromatic rings in 4 are out of heteroaromatic ring. Spectrophotometric studies in methanol solution revealed that the ligand 3 can be successfully applied to selective amino acid recognition.
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Papers by Abdollah Yari