A multivariate factorial design was proposed for determination of p-synephrine. Novelty of presen... more A multivariate factorial design was proposed for determination of p-synephrine. Novelty of present approach stems from consolidating multiple responses into a unified performance characteristic.
A simple, rapid, sensitive and accurate method for the determination of aciclovir, cefepime HCI, ... more A simple, rapid, sensitive and accurate method for the determination of aciclovir, cefepime HCI, etamsylate and metoclopramide HCI in pure form and in pharmaceutical formulations is developed.The method is based on the fomabon of tris(o-phenanthroline) iron(ll) complex (Ferroin) upon the reaction of the ated drugs wrth iron(lll )-o- phenanthroline mixture. The ferroin complex is colorimetncally measured at λmax 510 nm against a reagent blank. 0ptimization of the experimental conditions is described. Beer's law is obeyed in the concentration range from 0.25–30 µg ml−1 with molar absorpitivities (ε) ranging from 4.796 x 103–9.51 2 x 104 L.mol−1.cm−1 and Sandell sensitivities (S) of 2.129 x 10−3–34.5 x 10−3 µg cm−2. The developed method is applied successfully for the determination of the cited drugs in pure forms and in the corresponding pharmaceutical formulations without any interferences from common excipients.
A simple, rapid and sensitive spectrophotometric method has been developed for the quantitative d... more A simple, rapid and sensitive spectrophotometric method has been developed for the quantitative determination of five drugs of pharmaceutical interest; cefepime HCI , cefoperazone Na , ceftazidime pentahydrate , cefuroxime Na and etamsylate in pure form as well as in pharmaceuticals. The method is based on the reduction of the chromogenic agent , ammonium molybdate (Mo6+), to molybdenum blue (Mo5+) by the examined drugs in sulphuric acid medium and by aid of heating in boiling water bath. The resulting "blue…
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 5, 2018
Charge-transfer complex (CTC) formation between tioconazole (TCZ) as an n-electron donor and 7, 7... more Charge-transfer complex (CTC) formation between tioconazole (TCZ) as an n-electron donor and 7, 7, 8, 8-tetracyanoquinodimethane (TCNQ) as a π-acceptor was studied spectrophotometrically with an accompanying kinetic and thermodynamic investigation. Multivariate data analysis via a set of experimental designs was executed for this purpose. A 2 - two-level full factorial design (FFD) was used for inspecting the proposed variables while a face-centered central composite design (FCCCD) was used to adjust the levels of variables proved to be significant. Two responses were quantified as a result of this interaction; complex I (Y1, measured at 743 nm) and complex II (Y2, measured at 842 nm). Derringer's function and overlaid contour plots were used to concurrently optimize both responses. Benesi-Hildebrand equation was applied to determine of formation constant (K), and the molar absorptivity (Ɛ) of the formed complex. Different thermodynamic parameters; the standard Gibbs free energy...
An experimental design was adopted for determination of MD·HCl. The novelty of the current approa... more An experimental design was adopted for determination of MD·HCl. The novelty of the current approach arises from being multivariate compared to traditional univariate techniques.
A simple, rapid and sensitive spectrophotometric method for the determination of micro amounts of... more A simple, rapid and sensitive spectrophotometric method for the determination of micro amounts of cefepime hydrochloride and cefuroxime sodium is described. The method is based on reduction of 2,3,5-triphenyltetrazolium chloride (TTC) by the cited drugs in slightly alkaline medium leading to formation of a highly colored formazan derivative. Different variables affecting the color development were investigated and optimized. Absorbance measurements were made at 483 nm. Under the proposed conditions, this method is applicable over concentration range of 4–50 µg ml-1with molar absorpitivities ranging from 5.208 x 103–1.217 x 104 L.mol-1.cm-1and Sandell's sensitivities ranging from 1.007 x 10-3–2.727 x10-3µg cm-2. The proposed method was successfully applied for analysis of the cited drugs in formulations and the recovery percentages ranged from 99.47 to 99.8%. The results obtained demonstrated that the proposed method is equally accurate, precise and reproducible as the reported m...
ABSTRACT The self-association (micellization) behavior of etilefrine HCl, an amphiphilic drug, in... more ABSTRACT The self-association (micellization) behavior of etilefrine HCl, an amphiphilic drug, in aqueous electrolyte solution has been investigated as a function of temperature and sodium chloride (NaCl) concentration by conductivity and H-1 NMR measurements. The critical micelle concentration (CMC) was calculated from the inflection in the data obtained from both techniques. The CMC and the degree of ionization (alpha) values were determined over the temperature range (298.15 to 313.15) K in water and in presence of different concentrations of NaCl. The thermodynamic parameters of micellization for etilefrine HCl i.e. the standard Gibbs free energy change Delta G degrees(m), the standard enthalpy change, Delta H degrees(m), and the standard entropy change, Delta S degrees(m), were evaluated according to the pseudo-phase model. The obtained CMC values, in presence and absence of electrolyte, showed an inverted U-shaped behavior. While the degree of micelle ionization (alpha) showed a linear response to the increase in temperature in absence of electrolyte, addition of NaCl did not cause a specific response.
In this paper, pulsed streaming potentials generated in plastic microfluidic channels are used fo... more In this paper, pulsed streaming potentials generated in plastic microfluidic channels are used for the label-free detection of some model analytes. The microchannels are fabricated with the commodity plastic cyclic olefin copolymer (COC), and the detection signal arises from a change in the surface charge upon analyte adsorption on the modified microchannel surface. The role of the surface modification is to confer the microchannel with a predetermined charge and a particular specificity toward the adsorption of the target analyte. In this work, several target probes displaying different levels of specificity were investigated. Heparin and streptavidin were detected by adsorption on microchannel surfaces modified with protamine and biotin, respectively, whereas bovine serum albumin (BSA) and methylene blue (MB) showed nonspecific adsorption on almost any modified or unmodified COC microchannel surface. The magnitude of the streaming potential was found to be proportional to the liquid pressure and the surface charge of the microchannel in accord with the Smoluchowski equation. Because the relative polarity of the streaming potential is determined by the surface charge, the most straightforward detection with this method occurs when the charge is reversed upon analyte adsorption. This strategy was used for the species described in this work, and the lowest concentrations detected were approximately 0.01 units/mL for heparin (below clinical relevance), approximately 10 (-9) M for BSA, and approximately 10 (-6) M for MB. Unlike the conventional method of steady flow, in this work, the streaming potentials were measured under pulsed conditions of flow and using nonreference electrodes. This approach removes the need of special electrolytes as it is usually required when using reference electrodes, and at the same time, it mitigates the interference of electrochemical drift from the electrodes. Relative standard deviations of approximately 1-2% and measuring times of approximately 10 s are readily attained with this experimental setup. The on-channel modification of the surface was carried out by UV-photografting methods given the significant UV transparency of COC.
A multivariate factorial design was proposed for determination of p-synephrine. Novelty of presen... more A multivariate factorial design was proposed for determination of p-synephrine. Novelty of present approach stems from consolidating multiple responses into a unified performance characteristic.
A simple, rapid, sensitive and accurate method for the determination of aciclovir, cefepime HCI, ... more A simple, rapid, sensitive and accurate method for the determination of aciclovir, cefepime HCI, etamsylate and metoclopramide HCI in pure form and in pharmaceutical formulations is developed.The method is based on the fomabon of tris(o-phenanthroline) iron(ll) complex (Ferroin) upon the reaction of the ated drugs wrth iron(lll )-o- phenanthroline mixture. The ferroin complex is colorimetncally measured at λmax 510 nm against a reagent blank. 0ptimization of the experimental conditions is described. Beer's law is obeyed in the concentration range from 0.25–30 µg ml−1 with molar absorpitivities (ε) ranging from 4.796 x 103–9.51 2 x 104 L.mol−1.cm−1 and Sandell sensitivities (S) of 2.129 x 10−3–34.5 x 10−3 µg cm−2. The developed method is applied successfully for the determination of the cited drugs in pure forms and in the corresponding pharmaceutical formulations without any interferences from common excipients.
A simple, rapid and sensitive spectrophotometric method has been developed for the quantitative d... more A simple, rapid and sensitive spectrophotometric method has been developed for the quantitative determination of five drugs of pharmaceutical interest; cefepime HCI , cefoperazone Na , ceftazidime pentahydrate , cefuroxime Na and etamsylate in pure form as well as in pharmaceuticals. The method is based on the reduction of the chromogenic agent , ammonium molybdate (Mo6+), to molybdenum blue (Mo5+) by the examined drugs in sulphuric acid medium and by aid of heating in boiling water bath. The resulting "blue…
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 5, 2018
Charge-transfer complex (CTC) formation between tioconazole (TCZ) as an n-electron donor and 7, 7... more Charge-transfer complex (CTC) formation between tioconazole (TCZ) as an n-electron donor and 7, 7, 8, 8-tetracyanoquinodimethane (TCNQ) as a π-acceptor was studied spectrophotometrically with an accompanying kinetic and thermodynamic investigation. Multivariate data analysis via a set of experimental designs was executed for this purpose. A 2 - two-level full factorial design (FFD) was used for inspecting the proposed variables while a face-centered central composite design (FCCCD) was used to adjust the levels of variables proved to be significant. Two responses were quantified as a result of this interaction; complex I (Y1, measured at 743 nm) and complex II (Y2, measured at 842 nm). Derringer's function and overlaid contour plots were used to concurrently optimize both responses. Benesi-Hildebrand equation was applied to determine of formation constant (K), and the molar absorptivity (Ɛ) of the formed complex. Different thermodynamic parameters; the standard Gibbs free energy...
An experimental design was adopted for determination of MD·HCl. The novelty of the current approa... more An experimental design was adopted for determination of MD·HCl. The novelty of the current approach arises from being multivariate compared to traditional univariate techniques.
A simple, rapid and sensitive spectrophotometric method for the determination of micro amounts of... more A simple, rapid and sensitive spectrophotometric method for the determination of micro amounts of cefepime hydrochloride and cefuroxime sodium is described. The method is based on reduction of 2,3,5-triphenyltetrazolium chloride (TTC) by the cited drugs in slightly alkaline medium leading to formation of a highly colored formazan derivative. Different variables affecting the color development were investigated and optimized. Absorbance measurements were made at 483 nm. Under the proposed conditions, this method is applicable over concentration range of 4–50 µg ml-1with molar absorpitivities ranging from 5.208 x 103–1.217 x 104 L.mol-1.cm-1and Sandell's sensitivities ranging from 1.007 x 10-3–2.727 x10-3µg cm-2. The proposed method was successfully applied for analysis of the cited drugs in formulations and the recovery percentages ranged from 99.47 to 99.8%. The results obtained demonstrated that the proposed method is equally accurate, precise and reproducible as the reported m...
ABSTRACT The self-association (micellization) behavior of etilefrine HCl, an amphiphilic drug, in... more ABSTRACT The self-association (micellization) behavior of etilefrine HCl, an amphiphilic drug, in aqueous electrolyte solution has been investigated as a function of temperature and sodium chloride (NaCl) concentration by conductivity and H-1 NMR measurements. The critical micelle concentration (CMC) was calculated from the inflection in the data obtained from both techniques. The CMC and the degree of ionization (alpha) values were determined over the temperature range (298.15 to 313.15) K in water and in presence of different concentrations of NaCl. The thermodynamic parameters of micellization for etilefrine HCl i.e. the standard Gibbs free energy change Delta G degrees(m), the standard enthalpy change, Delta H degrees(m), and the standard entropy change, Delta S degrees(m), were evaluated according to the pseudo-phase model. The obtained CMC values, in presence and absence of electrolyte, showed an inverted U-shaped behavior. While the degree of micelle ionization (alpha) showed a linear response to the increase in temperature in absence of electrolyte, addition of NaCl did not cause a specific response.
In this paper, pulsed streaming potentials generated in plastic microfluidic channels are used fo... more In this paper, pulsed streaming potentials generated in plastic microfluidic channels are used for the label-free detection of some model analytes. The microchannels are fabricated with the commodity plastic cyclic olefin copolymer (COC), and the detection signal arises from a change in the surface charge upon analyte adsorption on the modified microchannel surface. The role of the surface modification is to confer the microchannel with a predetermined charge and a particular specificity toward the adsorption of the target analyte. In this work, several target probes displaying different levels of specificity were investigated. Heparin and streptavidin were detected by adsorption on microchannel surfaces modified with protamine and biotin, respectively, whereas bovine serum albumin (BSA) and methylene blue (MB) showed nonspecific adsorption on almost any modified or unmodified COC microchannel surface. The magnitude of the streaming potential was found to be proportional to the liquid pressure and the surface charge of the microchannel in accord with the Smoluchowski equation. Because the relative polarity of the streaming potential is determined by the surface charge, the most straightforward detection with this method occurs when the charge is reversed upon analyte adsorption. This strategy was used for the species described in this work, and the lowest concentrations detected were approximately 0.01 units/mL for heparin (below clinical relevance), approximately 10 (-9) M for BSA, and approximately 10 (-6) M for MB. Unlike the conventional method of steady flow, in this work, the streaming potentials were measured under pulsed conditions of flow and using nonreference electrodes. This approach removes the need of special electrolytes as it is usually required when using reference electrodes, and at the same time, it mitigates the interference of electrochemical drift from the electrodes. Relative standard deviations of approximately 1-2% and measuring times of approximately 10 s are readily attained with this experimental setup. The on-channel modification of the surface was carried out by UV-photografting methods given the significant UV transparency of COC.
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