Mohamed Elmosallamy | King Saud University (original) (raw)
Papers by Mohamed Elmosallamy
Egyptian Journal of Chemistry
Analytical and Bioanalytical Chemistry, Oct 14, 2022
The first, novel solid-state membrane sensor for Zn(II) determination is developed based on ZnS n... more The first, novel solid-state membrane sensor for Zn(II) determination is developed based on ZnS nanoparticles. ZnS nanoparticles are synthesized by chemical co-precipitation and investigated via X-ray diffraction, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and impedance study. X-ray diffraction shows that the prepared ZnS nanoparticles have an average domain size of 5.72 nm, which is very close to the particle size obtained from TEM observations (6.30 nm). The ZnS nanoparticles are pressed into disks and examined as electroactive solid-state membrane. Solid-state membrane and coated wire sensors are fabricated. They display linear responses over concentration ranges of 1.0 × 10 −5 to 1.0 × 10 −1 mol L −1 Zn 2+ ions with cationic slopes of 28.9±0.2 and 25.9±0.2 mV decade −1 for the solid-state membrane and coated wire sensors, respectively. The lower limits of detection are 2.86 × 10 −6 and 4.60 × 10 −6 mol L −1 Zn 2+ ions for the solid-state membrane and coated wire sensors, respectively. The response time for the two sensors is instantaneous (1 s), and the useful lifetimes for the solid-state membrane and coated wire sensors are long (10 and 6 months, respectively). The solid-state membrane sensor is utilized for the quantification of Zn(II) ions in brass alloys and pharmaceutical preparations.
Simple and selective two different techniques are developed for the determination of oxomemazine ... more Simple and selective two different techniques are developed for the determination of oxomemazine in pharmaceutical preparations. A rapid (less than 6 min) and accurate high performance liquid chromatography(HPLC) method has been developed where chromatographic analysis is performed on Nova-Pak ® C 18 column (3.9 mm × 150 mm, 5 µm) with an ammonium formate buffer adjusted with formic acid to pH 3.0 and acetonitrile (75: 25, v/v) as a mobile phase, and detection at 235 nm. Good linearity (0.99, r 2), accuracy (≥ 99.20%), and precision (≤ 0.6 RSD) were obtained. Potentiometric measurements are based on tetrakis (p-chlorophenyl) borate-oxomemazine ion-pair complex as an electroactive species incorporating in a plasticized poly vinyl chloride (PVC) membrane with o-nitrophenyl octyl ether (o-NPOE) or dioctyl phthalate (DOP). The sensor exhibits fast and stable Nernstian response for oxomemazine over the concentration range of 1.0 × 10-5-1.0 × 10-2 mol L-1 and pH range of 3.5-6.0. The sensor shows reasonable selectivity towards oxomemazine hydrochloride over many cations. No significant interferences are caused by drug excipients and diluents. Results with an average recovery of 100.6% and a mean standard deviation of 0.77% of the nominal were obtained.
Journal of Taibah University for Science, 2013
A new and rapid potentiometric method for determination of flucloxacillin is developed. The metho... more 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.
Open Journal of Analytical and Bioanalytical Chemistry, 2020
An HPLC method had been developed and validated for rapid simultaneous separation and determinati... more An HPLC method had been developed and validated for rapid simultaneous separation and determination of the two antihypertensive drugs, amlodipine and xipamide in human plasma within 5 minutes. Drugs are extracted from plasma using methanol, the environmentally benign solvent, for protein precipitation technique. Separation was carried out on a Thermo Scientifi c ® BDS Hypersil C 8 column (5μm, 2.50x4.60 mm) using a mobile phase of methanol: 0.025M KH 2 PO 4 (70: 30, v/v) adjusted to pH 3.49 with ortho-phosphoric acid at ambient temperature. The fl ow rate was 1 ml/min and maximum absorption was measured using DAD detector at 235nm. The retention times of amlodipine and xipamide were recorded to be 4.51 and 3.38 minutes, respectively, indicating a shorter analysis time. Limits of detection were reported to be 0.17 and 0.25 μg/ml for amlodipine and xipamide, respectively, showing a high degree of the method sensitivity. The method was then validated according to FDA guidelines for the determination of the drugs clinically in human plasma specially regarding pharmacokinetic and bioequivalence studies.
South African journal of chemistry, 2003
The reaction of iodine (acceptor) and nickel(II) acetylacetonate (donor) was studied photometrica... more The reaction of iodine (acceptor) and nickel(II) acetylacetonate (donor) was studied photometrically in different solvents such as chloroform, dichloromethane and carbon tetrachloride at room temperature. The results indicate the formation of a 1: 1 charge-transfer complex in each solvent and the iodine complex is formulated as the triiodide species [Ni(acac)2]2I+.I3-, based on the characteristic electronic absorptions of the I3- ion at 361 and 285 nm, as well as on the far infrared absorption bands characteristic of the I3- ion with C2v symmetry. These bands are observed at 132, 101 and 84 cm-1 and are assigned to na(I-I), ns(I-I) and d(I3-), respectively. The values of the equilibrium constant (K), absorptivity (e) and oscillator strength (f) of the iodine complex are shown to be strongly dependent on the type of solvent used. The important role played by the solvent is suggested to be mainly due to the interaction of the ionic complex with the solvent. The proposed structure of t...
Reviews in Analytical Chemistry
Two new potentiometric sensors were created for the quantification of bisoprolol fumarate and alv... more Two new potentiometric sensors were created for the quantification of bisoprolol fumarate and alverine citrate in bulk pharmaceutical dosage forms and human serum. Bisoprolol and alverine sensors were manufactured by combining potassium tetrakis (p-chlorophenyl) borate ion pairs to serve as electroactive substances, plasticized poly (vinyl chloride) matrix membranes, and o-nitrophenyl octyl ether. They demonstrated high responses over the concentration ranges of 1.0×10−6 to 1.0×10−2 mol L−1 bisoprolol and alverine with close to Nernstian cationic slopes of 52 and 56 mV decade−1, respectively. The detection limits for bisoprolol and alverine were 2.6×10−6 and 1.75×10−6 mol L−1, respectively. For both medications, the response time was instantaneous (2.0 s). The working pH ranges for bisoprolol and alverine were 4.50–8.50 and 2.00–8.80, respectively. For both sensors, the life cycle was long (3 months). The sensors were used in pharmaceutical dosage types for the assay of bisoprolol a...
Electroanalysis, 2012
Six types of histamine potentiometric sensors are developed. They are based on using dibenzo-30-c... more Six types of histamine potentiometric sensors are developed. They are based on using dibenzo-30-crown-10 (DB30C10) with potassium tetrakis(p-chlorophenyl)borate lipophilic additive (Type I), dibenzo-30-crown-10 without additive (Type II), dibenzo-24-crown-8 (DB24C8) with the same additive (Type III), dibenzo-24-crown-8 without additive (Type IV), dibenzo-18-crown-6 with the additive (Type V) and dibenzo-18-crown-6 without additive (Type VI) as neutral carriers for histamine. Sensors based on dibenzo-30-crown-10 with (PTp-C1PB) lipophilic additive (Type I) and dibenzo-30-crown-10 without additive (Type II) show good response. The other sensors Types III-VI show poor response in terms of calibration range and slope.
Electroanalysis, 2016
Three neurotransmitter sensors for dopamine, serotonin, and epinephrine have been developed. Pote... more 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 mVdecade@1 and detection limit of 4.0X10@5 molL@1 dopamine, cationic slope of 55.9 mVdecade@1 and detection limit of 4.0X 10@5 molL@1 serotonin, and cationic slope of 54.4 mVdecade @1 and detection limit of 2.0X10@5 molL@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.
Spectrochimica Acta Part a Molecular and Biomolecular Spectroscopy, Oct 1, 2005
The interaction of the mixed oxygen-nitrogen cyclic base, N,N'-dibenzyl-1,4,10,13-tetraox... more The interaction of the mixed oxygen-nitrogen cyclic base, N,N'-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (DD18C6) with pi-acceptors such as picric acid (HPA) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) has been studied spectrophotometrically in chloroform at 25 degrees C. The results obtained indicate the formation of 1:4 charge-transfer complexes with the general formula (DD18C6)(acceptor)4. The electronic and infrared spectra of charge-transfer complexes along with the (1)H NMR spectra were recorded and discussed. Based on the data obtained, the complexes were formulated as [(DD18C6H2)(HPA)2](PA)2 and [(DD18C6H2)(DDQ)2](DDQH)2. A general mechanism explaining the formation of the DDQ complex has been suggested.
Http Dx Doi Org 10 1080 0095897050012279, Jan 25, 2007
ABSTRACT Four new dioxouranium(VI) complexes, [UO2(acac-o-phdn)(L)] where L = H2O, py, DMF and Et... more ABSTRACT Four new dioxouranium(VI) complexes, [UO2(acac-o-phdn)(L)] where L = H2O, py, DMF and Et3N, with the tetradentate dibasic Schiff base (acac-o-phdn), derived from condensation of acetylacetone with o-phenylene diamine have been synthesized. The infrared spectra were obtained and full assignments of all the observed vibrations are proposed on the basis of C2v symmetry for H2O and py complexes and Cs for the other two complexes, respectively. The bond stretching force constant and bond length of the U=O bond for the four complexes were calculated. Differential thermal analysis (DTA) and thermogravimetric (TG) analysis of the complexes were also carried out.
Pharmazie, Feb 1, 2003
A novel potentiometric PVC membrane sensor for determination of diclofenac in pharmaceutical prep... more A novel potentiometric PVC membrane sensor for determination of diclofenac in pharmaceutical preparations has been developed. The sensor is based on the use of the 2,4,6-tri(2-pyridyl)-s-triazine iron(II) diclofenac complex [diclofenac-TPTZ-Fe(II)] as an electroactive material in a plasticized PVC membrane matrix. The sensor exhibits fast, stable and near Nernstian response for diclofenac over the concentration range 10(-2)-10(-6) M and pH 5.5-9.5. Application to quality control analysis of diclofenac in various dosage forms shows an average recovery of 99% with a mean standard deviation of 0.2%. No significant interferences are caused by inorganic and organic anions and various drug excipients and diluents.
Mikrochimica Acta, Jul 31, 1999
Abstract. Novel miniaturized carboxylated poly(vinyl chloride) and poly fluoro sulfonate (Nafion)... more Abstract. 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 incor-porate the ...
Analytical sciences : the international journal of the Japan Society for Analytical Chemistry, 2014
New, simple and convenient potentiometric and spectrophotometric methods are described for the de... more New, simple and convenient potentiometric and spectrophotometric methods are described for the determination of dextromethorphan hydrobromide (DXM) in pharmaceutical preparations. The potentiometric technique is based on developing a potentiometric sensor incorporating the dextromethorphan tetrakis(p-chlorophenyl)borate ion-pair complex as an electroactive species in a plasticized PVC matrix membrane with o-nitophenyl octyl ether or dioctyl phthalate. The sensor shows a rapid near Nernstian response of over 1 × 10(-5) - 1 × 10(-2) mol L(-1) dextromethorphan in the pH range of 3.0 - 9.0. The detection limit is 2 × 10(-6) mol L(-1) DXM and the response time is instantaneous (2 s). The proposed spectrophotometric technique involves the reaction of DXM with eriochrom black T (EBT) to form an ion-associate complex. Solvent extraction is used to improve the selectivity of the method. The optimal extraction and reaction conditions have been studied, and the analytical characteristics of th...
Spectroscopy Letters, 1997
The reactions of π-electron acceptors such as 1-chloro-2,4,6-trinitrobenzene (picryl chloride), 7... more The reactions of π-electron acceptors such as 1-chloro-2,4,6-trinitrobenzene (picryl chloride), 7,7′,8,8′-tetracyanoquino-dimethane (TCNQ), tetrachloro-p-benzoquinone (chloranil) and tetra-cyanoethylene (TCNE) with the cyclic polyamine base 1,4,8,11-tetraazacyclotetradecane (TACTD) have been investigated in CHCl3 solvent. The data indicate the formation of the CT-complexes with the general formula [(TACTD) (acceptor)2]. The 1: 2 stoichiometry of the (TACTD)-acceptor was based on elemental analysis and infrared spectra of
Microchimica Acta, 2005
A potentiometric poly(vinyl chloride) membrane sensor for determination of saccharin is described... more A potentiometric poly(vinyl chloride) membrane sensor for determination of saccharin is described. It is based on the use of Aliquat 336S-saccharinate ion-pair as an electroactive material in plasticized PVC membranes with o-nitrophenyloctylether or dioctylphthalate. The sensor is conditioned for at least two days in 0.1 mol L À1 sodium saccharinate before use. It exhibits fast, stable and Nernstian response for saccharinate ions over the concentration range of 1.0Â 10 À1-5.0Â10 À5 mol L À1 and pH range of 4.5-11. The sensor is used for determination of saccharin in some dosage forms. Results with an average recovery of 101% and a mean standard deviation of 0.2% are obtained which is compared favourably with data obtained using the British pharmacopoeia method. The sensor shows reasonable selectivity towards saccharin in presence of many anions and natural sweeteners.
Mikrochimica Acta, 1999
Abstract. Novel miniaturized carboxylated poly(vinyl chloride) and poly fluoro sulfonate (Nafion)... more Abstract. 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 incor-porate the ...
Mikrochimica Acta, 1998
New methods are developed for the determination of cinnarizine in various dosage forms. They are ... more New methods are developed for the determination of cinnarizine in various dosage forms. They are based on the reaction of cinnarizinium cation with cobalt tetrathiocyanate anion, whereby a sparingly soluble blue 2:1 drug: reagent ion-pair complex is quantitatively formed. The complex is (a) extracted with nitrobenzene and spectrophotometrically measured at 622 nm; (b) extracted with nitrobenzene and nebulized in an air-acetylene flame for atomic absorption spectrometric monitoring of cobalt at 242.5 nm; and (c) dispersed in a PVC membrane plasticized with 2-nitrophenyloctyl ether and used as a sensor for direct potentiometric determination of the drug. Optimum reaction conditions and performances of the three analytical techniques are evaluated and compared. At the 25 mg level of cinnarizine, the three methods give results with equal accuracy and precision. The average recovery is 98-99% of the nominal and the mean standard deviation is 0.7%. No significant interferences are caused by drug excipients and diluents.
Journal of Pharmaceutical and Biomedical Analysis, 2005
Construction and characterization of potentiometric membrane sensors for quantification of diclof... more Construction and characterization of potentiometric membrane sensors for quantification of diclofenac and warfarin drugs are described. The membranes of the sensors incorporate 1.8 wt.% iron(II)-phthalocyanine (Pc) as a molecular recognition reagent, 64.3 wt.% dibutylsebacate (DBS) solvent mediator, 1.8 wt.% tridodecylmethylammonium chloride (TDMAC) as membrane additive and 32.1 wt.% poly(vinyl chloride) (PVC) as a matrix. The sensors display linear response for 1 x 10(-2) to 9 x 10(-6) mol l(-1) (detection limit 5.4 x 10(-6) mol l(-1)) and 1 x 10(-2) to 5 x 10(-6) mol l(-1) (detection limit 3 x 10(-6) mol l(-1)) with anionic slopes of -61 +/- 1 and -63 +/- 1 mVdecade(-1) over the pH range 5.5-9 for declofenac and warfarin, respectively. Validation of the assay methods according to the quality assurance standards confirms their suitability for quality control purposes. Use of the sensor for the assay of various formulations of the drugs shows a mean average recovery of 99.7% of the nominal values and a mean precision of +/-0.3%. Significantly improved accuracy, precision, response time, stability, selectivity and sensitivity are offered by these simple and cost-effective potentiometric sensors compared with other standard techniques.
Egyptian Journal of Chemistry
Analytical and Bioanalytical Chemistry, Oct 14, 2022
The first, novel solid-state membrane sensor for Zn(II) determination is developed based on ZnS n... more The first, novel solid-state membrane sensor for Zn(II) determination is developed based on ZnS nanoparticles. ZnS nanoparticles are synthesized by chemical co-precipitation and investigated via X-ray diffraction, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and impedance study. X-ray diffraction shows that the prepared ZnS nanoparticles have an average domain size of 5.72 nm, which is very close to the particle size obtained from TEM observations (6.30 nm). The ZnS nanoparticles are pressed into disks and examined as electroactive solid-state membrane. Solid-state membrane and coated wire sensors are fabricated. They display linear responses over concentration ranges of 1.0 × 10 −5 to 1.0 × 10 −1 mol L −1 Zn 2+ ions with cationic slopes of 28.9±0.2 and 25.9±0.2 mV decade −1 for the solid-state membrane and coated wire sensors, respectively. The lower limits of detection are 2.86 × 10 −6 and 4.60 × 10 −6 mol L −1 Zn 2+ ions for the solid-state membrane and coated wire sensors, respectively. The response time for the two sensors is instantaneous (1 s), and the useful lifetimes for the solid-state membrane and coated wire sensors are long (10 and 6 months, respectively). The solid-state membrane sensor is utilized for the quantification of Zn(II) ions in brass alloys and pharmaceutical preparations.
Simple and selective two different techniques are developed for the determination of oxomemazine ... more Simple and selective two different techniques are developed for the determination of oxomemazine in pharmaceutical preparations. A rapid (less than 6 min) and accurate high performance liquid chromatography(HPLC) method has been developed where chromatographic analysis is performed on Nova-Pak ® C 18 column (3.9 mm × 150 mm, 5 µm) with an ammonium formate buffer adjusted with formic acid to pH 3.0 and acetonitrile (75: 25, v/v) as a mobile phase, and detection at 235 nm. Good linearity (0.99, r 2), accuracy (≥ 99.20%), and precision (≤ 0.6 RSD) were obtained. Potentiometric measurements are based on tetrakis (p-chlorophenyl) borate-oxomemazine ion-pair complex as an electroactive species incorporating in a plasticized poly vinyl chloride (PVC) membrane with o-nitrophenyl octyl ether (o-NPOE) or dioctyl phthalate (DOP). The sensor exhibits fast and stable Nernstian response for oxomemazine over the concentration range of 1.0 × 10-5-1.0 × 10-2 mol L-1 and pH range of 3.5-6.0. The sensor shows reasonable selectivity towards oxomemazine hydrochloride over many cations. No significant interferences are caused by drug excipients and diluents. Results with an average recovery of 100.6% and a mean standard deviation of 0.77% of the nominal were obtained.
Journal of Taibah University for Science, 2013
A new and rapid potentiometric method for determination of flucloxacillin is developed. The metho... more 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.
Open Journal of Analytical and Bioanalytical Chemistry, 2020
An HPLC method had been developed and validated for rapid simultaneous separation and determinati... more An HPLC method had been developed and validated for rapid simultaneous separation and determination of the two antihypertensive drugs, amlodipine and xipamide in human plasma within 5 minutes. Drugs are extracted from plasma using methanol, the environmentally benign solvent, for protein precipitation technique. Separation was carried out on a Thermo Scientifi c ® BDS Hypersil C 8 column (5μm, 2.50x4.60 mm) using a mobile phase of methanol: 0.025M KH 2 PO 4 (70: 30, v/v) adjusted to pH 3.49 with ortho-phosphoric acid at ambient temperature. The fl ow rate was 1 ml/min and maximum absorption was measured using DAD detector at 235nm. The retention times of amlodipine and xipamide were recorded to be 4.51 and 3.38 minutes, respectively, indicating a shorter analysis time. Limits of detection were reported to be 0.17 and 0.25 μg/ml for amlodipine and xipamide, respectively, showing a high degree of the method sensitivity. The method was then validated according to FDA guidelines for the determination of the drugs clinically in human plasma specially regarding pharmacokinetic and bioequivalence studies.
South African journal of chemistry, 2003
The reaction of iodine (acceptor) and nickel(II) acetylacetonate (donor) was studied photometrica... more The reaction of iodine (acceptor) and nickel(II) acetylacetonate (donor) was studied photometrically in different solvents such as chloroform, dichloromethane and carbon tetrachloride at room temperature. The results indicate the formation of a 1: 1 charge-transfer complex in each solvent and the iodine complex is formulated as the triiodide species [Ni(acac)2]2I+.I3-, based on the characteristic electronic absorptions of the I3- ion at 361 and 285 nm, as well as on the far infrared absorption bands characteristic of the I3- ion with C2v symmetry. These bands are observed at 132, 101 and 84 cm-1 and are assigned to na(I-I), ns(I-I) and d(I3-), respectively. The values of the equilibrium constant (K), absorptivity (e) and oscillator strength (f) of the iodine complex are shown to be strongly dependent on the type of solvent used. The important role played by the solvent is suggested to be mainly due to the interaction of the ionic complex with the solvent. The proposed structure of t...
Reviews in Analytical Chemistry
Two new potentiometric sensors were created for the quantification of bisoprolol fumarate and alv... more Two new potentiometric sensors were created for the quantification of bisoprolol fumarate and alverine citrate in bulk pharmaceutical dosage forms and human serum. Bisoprolol and alverine sensors were manufactured by combining potassium tetrakis (p-chlorophenyl) borate ion pairs to serve as electroactive substances, plasticized poly (vinyl chloride) matrix membranes, and o-nitrophenyl octyl ether. They demonstrated high responses over the concentration ranges of 1.0×10−6 to 1.0×10−2 mol L−1 bisoprolol and alverine with close to Nernstian cationic slopes of 52 and 56 mV decade−1, respectively. The detection limits for bisoprolol and alverine were 2.6×10−6 and 1.75×10−6 mol L−1, respectively. For both medications, the response time was instantaneous (2.0 s). The working pH ranges for bisoprolol and alverine were 4.50–8.50 and 2.00–8.80, respectively. For both sensors, the life cycle was long (3 months). The sensors were used in pharmaceutical dosage types for the assay of bisoprolol a...
Electroanalysis, 2012
Six types of histamine potentiometric sensors are developed. They are based on using dibenzo-30-c... more Six types of histamine potentiometric sensors are developed. They are based on using dibenzo-30-crown-10 (DB30C10) with potassium tetrakis(p-chlorophenyl)borate lipophilic additive (Type I), dibenzo-30-crown-10 without additive (Type II), dibenzo-24-crown-8 (DB24C8) with the same additive (Type III), dibenzo-24-crown-8 without additive (Type IV), dibenzo-18-crown-6 with the additive (Type V) and dibenzo-18-crown-6 without additive (Type VI) as neutral carriers for histamine. Sensors based on dibenzo-30-crown-10 with (PTp-C1PB) lipophilic additive (Type I) and dibenzo-30-crown-10 without additive (Type II) show good response. The other sensors Types III-VI show poor response in terms of calibration range and slope.
Electroanalysis, 2016
Three neurotransmitter sensors for dopamine, serotonin, and epinephrine have been developed. Pote... more 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 mVdecade@1 and detection limit of 4.0X10@5 molL@1 dopamine, cationic slope of 55.9 mVdecade@1 and detection limit of 4.0X 10@5 molL@1 serotonin, and cationic slope of 54.4 mVdecade @1 and detection limit of 2.0X10@5 molL@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.
Spectrochimica Acta Part a Molecular and Biomolecular Spectroscopy, Oct 1, 2005
The interaction of the mixed oxygen-nitrogen cyclic base, N,N'-dibenzyl-1,4,10,13-tetraox... more The interaction of the mixed oxygen-nitrogen cyclic base, N,N'-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (DD18C6) with pi-acceptors such as picric acid (HPA) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) has been studied spectrophotometrically in chloroform at 25 degrees C. The results obtained indicate the formation of 1:4 charge-transfer complexes with the general formula (DD18C6)(acceptor)4. The electronic and infrared spectra of charge-transfer complexes along with the (1)H NMR spectra were recorded and discussed. Based on the data obtained, the complexes were formulated as [(DD18C6H2)(HPA)2](PA)2 and [(DD18C6H2)(DDQ)2](DDQH)2. A general mechanism explaining the formation of the DDQ complex has been suggested.
Http Dx Doi Org 10 1080 0095897050012279, Jan 25, 2007
ABSTRACT Four new dioxouranium(VI) complexes, [UO2(acac-o-phdn)(L)] where L = H2O, py, DMF and Et... more ABSTRACT Four new dioxouranium(VI) complexes, [UO2(acac-o-phdn)(L)] where L = H2O, py, DMF and Et3N, with the tetradentate dibasic Schiff base (acac-o-phdn), derived from condensation of acetylacetone with o-phenylene diamine have been synthesized. The infrared spectra were obtained and full assignments of all the observed vibrations are proposed on the basis of C2v symmetry for H2O and py complexes and Cs for the other two complexes, respectively. The bond stretching force constant and bond length of the U=O bond for the four complexes were calculated. Differential thermal analysis (DTA) and thermogravimetric (TG) analysis of the complexes were also carried out.
Pharmazie, Feb 1, 2003
A novel potentiometric PVC membrane sensor for determination of diclofenac in pharmaceutical prep... more A novel potentiometric PVC membrane sensor for determination of diclofenac in pharmaceutical preparations has been developed. The sensor is based on the use of the 2,4,6-tri(2-pyridyl)-s-triazine iron(II) diclofenac complex [diclofenac-TPTZ-Fe(II)] as an electroactive material in a plasticized PVC membrane matrix. The sensor exhibits fast, stable and near Nernstian response for diclofenac over the concentration range 10(-2)-10(-6) M and pH 5.5-9.5. Application to quality control analysis of diclofenac in various dosage forms shows an average recovery of 99% with a mean standard deviation of 0.2%. No significant interferences are caused by inorganic and organic anions and various drug excipients and diluents.
Mikrochimica Acta, Jul 31, 1999
Abstract. Novel miniaturized carboxylated poly(vinyl chloride) and poly fluoro sulfonate (Nafion)... more Abstract. 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 incor-porate the ...
Analytical sciences : the international journal of the Japan Society for Analytical Chemistry, 2014
New, simple and convenient potentiometric and spectrophotometric methods are described for the de... more New, simple and convenient potentiometric and spectrophotometric methods are described for the determination of dextromethorphan hydrobromide (DXM) in pharmaceutical preparations. The potentiometric technique is based on developing a potentiometric sensor incorporating the dextromethorphan tetrakis(p-chlorophenyl)borate ion-pair complex as an electroactive species in a plasticized PVC matrix membrane with o-nitophenyl octyl ether or dioctyl phthalate. The sensor shows a rapid near Nernstian response of over 1 × 10(-5) - 1 × 10(-2) mol L(-1) dextromethorphan in the pH range of 3.0 - 9.0. The detection limit is 2 × 10(-6) mol L(-1) DXM and the response time is instantaneous (2 s). The proposed spectrophotometric technique involves the reaction of DXM with eriochrom black T (EBT) to form an ion-associate complex. Solvent extraction is used to improve the selectivity of the method. The optimal extraction and reaction conditions have been studied, and the analytical characteristics of th...
Spectroscopy Letters, 1997
The reactions of π-electron acceptors such as 1-chloro-2,4,6-trinitrobenzene (picryl chloride), 7... more The reactions of π-electron acceptors such as 1-chloro-2,4,6-trinitrobenzene (picryl chloride), 7,7′,8,8′-tetracyanoquino-dimethane (TCNQ), tetrachloro-p-benzoquinone (chloranil) and tetra-cyanoethylene (TCNE) with the cyclic polyamine base 1,4,8,11-tetraazacyclotetradecane (TACTD) have been investigated in CHCl3 solvent. The data indicate the formation of the CT-complexes with the general formula [(TACTD) (acceptor)2]. The 1: 2 stoichiometry of the (TACTD)-acceptor was based on elemental analysis and infrared spectra of
Microchimica Acta, 2005
A potentiometric poly(vinyl chloride) membrane sensor for determination of saccharin is described... more A potentiometric poly(vinyl chloride) membrane sensor for determination of saccharin is described. It is based on the use of Aliquat 336S-saccharinate ion-pair as an electroactive material in plasticized PVC membranes with o-nitrophenyloctylether or dioctylphthalate. The sensor is conditioned for at least two days in 0.1 mol L À1 sodium saccharinate before use. It exhibits fast, stable and Nernstian response for saccharinate ions over the concentration range of 1.0Â 10 À1-5.0Â10 À5 mol L À1 and pH range of 4.5-11. The sensor is used for determination of saccharin in some dosage forms. Results with an average recovery of 101% and a mean standard deviation of 0.2% are obtained which is compared favourably with data obtained using the British pharmacopoeia method. The sensor shows reasonable selectivity towards saccharin in presence of many anions and natural sweeteners.
Mikrochimica Acta, 1999
Abstract. Novel miniaturized carboxylated poly(vinyl chloride) and poly fluoro sulfonate (Nafion)... more Abstract. 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 incor-porate the ...
Mikrochimica Acta, 1998
New methods are developed for the determination of cinnarizine in various dosage forms. They are ... more New methods are developed for the determination of cinnarizine in various dosage forms. They are based on the reaction of cinnarizinium cation with cobalt tetrathiocyanate anion, whereby a sparingly soluble blue 2:1 drug: reagent ion-pair complex is quantitatively formed. The complex is (a) extracted with nitrobenzene and spectrophotometrically measured at 622 nm; (b) extracted with nitrobenzene and nebulized in an air-acetylene flame for atomic absorption spectrometric monitoring of cobalt at 242.5 nm; and (c) dispersed in a PVC membrane plasticized with 2-nitrophenyloctyl ether and used as a sensor for direct potentiometric determination of the drug. Optimum reaction conditions and performances of the three analytical techniques are evaluated and compared. At the 25 mg level of cinnarizine, the three methods give results with equal accuracy and precision. The average recovery is 98-99% of the nominal and the mean standard deviation is 0.7%. No significant interferences are caused by drug excipients and diluents.
Journal of Pharmaceutical and Biomedical Analysis, 2005
Construction and characterization of potentiometric membrane sensors for quantification of diclof... more Construction and characterization of potentiometric membrane sensors for quantification of diclofenac and warfarin drugs are described. The membranes of the sensors incorporate 1.8 wt.% iron(II)-phthalocyanine (Pc) as a molecular recognition reagent, 64.3 wt.% dibutylsebacate (DBS) solvent mediator, 1.8 wt.% tridodecylmethylammonium chloride (TDMAC) as membrane additive and 32.1 wt.% poly(vinyl chloride) (PVC) as a matrix. The sensors display linear response for 1 x 10(-2) to 9 x 10(-6) mol l(-1) (detection limit 5.4 x 10(-6) mol l(-1)) and 1 x 10(-2) to 5 x 10(-6) mol l(-1) (detection limit 3 x 10(-6) mol l(-1)) with anionic slopes of -61 +/- 1 and -63 +/- 1 mVdecade(-1) over the pH range 5.5-9 for declofenac and warfarin, respectively. Validation of the assay methods according to the quality assurance standards confirms their suitability for quality control purposes. Use of the sensor for the assay of various formulations of the drugs shows a mean average recovery of 99.7% of the nominal values and a mean precision of +/-0.3%. Significantly improved accuracy, precision, response time, stability, selectivity and sensitivity are offered by these simple and cost-effective potentiometric sensors compared with other standard techniques.