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Polonca Trebše - One of the best experts on this subject based on the ideXlab platform.

  • photochemical fate and photocatalysis of 3 5 6 trichloro 2 pyridinol Degradation Product of chlorpyrifos
    Chemosphere, 2016
    Co-Authors: Romina žabar, Polonca Trebše, Olga V. Polyakova, Mohamed Sarakha, A. T. Lebedev
    Abstract:

    In this study we have focused on 3,5,6-trichloro-2-pyridinol (TCP), Degradation Product of chlorpyrifos. Photolysis experiments were conducted in order to elucidate its Degradation mechanism. Identification of Products was performed using the LC-MS technique. To evaluate the mineralization efficiency, TiO2 photocatalytic study was performed. Under photolytic experimental conditions, the concentration of TCP after 120 min of irradiation reached 5.9 ± 1.5% of the initial concentration, while chloride concentration reached approximately 73% of total chloride concentration. The TOC measurements after 120 min of photocatalytic Degradation experiment revealed high mineralization rate, i.e. 53.6 ± 1.9%, while chloride concentration reached 26.6 mg L−1 what means almost quantitative transformation of organic chlorine into chloride. TIC chromatogram (ESI, negative ion mode) of the reaction mixture after 30 min of irradiation revealed the presence of several peaks. One of them has already been reported previously. Two other Products have been identified in this study for the first time. They have been formed by radical attack of the reactive OH• species on the carbonyl group followed by the corresponding N–C or C–C bond cleavages and recyclization with formation of the pyrrol structures substituted with carboxylic groups. Both deprotonated molecules easily lose CO2 in ESI conditions.

Ahmed Serag - One of the best experts on this subject based on the ideXlab platform.

  • different spectrophotometric methods applied for the analysis of simeprevir in the presence of its oxidative Degradation Product acomparative study
    Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2018
    Co-Authors: Nasr M Elabasawi, Ahmed Elolemy, Ahmed Serag
    Abstract:

    Five simple spectrophotometric methods were developed for the determination of simeprevir in the presence of its oxidative Degradation Product namely, ratio difference, mean centering, derivative ratio using the Savitsky-Golay filters, second derivative and continuous wavelet transform. These methods are linear in the range of 2.5-40μg/mL and validated according to the ICH guidelines. The obtained results of accuracy, repeatability and precision were found to be within the acceptable limits. The specificity of the proposed methods was tested using laboratory prepared mixtures and assessed by applying the standard addition technique. Furthermore, these methods were statistically comparable to RP-HPLC method and good results were obtained. So, they can be used for the routine analysis of simeprevir in quality-control laboratories.

  • molecular and quantum mechanical study for the separation of cefprozil in the presence of its alkaline Degradation Product using rp hplc with uv detection
    Journal of AOAC International, 2017
    Co-Authors: Khalid A M Attia, Mohammed W I Nassar, Mohamed B Elzeiny, Ahmed Serag
    Abstract:

    : A reversed-phase HPLC method (RP-HPLC) with UV detection was developed and validated for the quantitative determination of cefprozil, a second-generation cephalosporin. Due to β-lactam ring instability under alkaline conditions, this RP-HPLC method was applied for the determination of cefprozil in the presence of its possible Degradation Product. The interactions that govern the separation process with stationary phase were investigated at both molecular and quantum mechanical levels. Moreover, electrostatic potential maps were generated to determine the sites of interaction with mobile phase. The suggested method was validated in compliance with International Conference on Harmonization guidelines and successfully applied for the determination of cefprozil in its commercial pharmaceutical formulation.

  • stability indicating methods for the analysis of cefprozil in the presence of its alkaline induced Degradation Product
    Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2016
    Co-Authors: Khalid A M Attia, Mohammed W I Nassar, Mohamed B Elzeiny, Ahmed Serag
    Abstract:

    Three simple, specific, accurate and precise spectrophotometric methods were developed for the determination of cefprozil (CZ) in the presence of its alkaline induced Degradation Product (DCZ). The first method was the bivariate method, while the two other multivariate methods were partial least squares (PLS) and spectral residual augmented classical least squares (SRACLS). The multivariate methods were applied with and without variable selection procedure (genetic algorithm GA). These methods were tested by analyzing laboratory prepared mixtures of the above drug with its alkaline induced Degradation Product and they were applied to its commercial pharmaceutical Products.

  • different approaches in manipulating ratio spectra applied for the analysis of cefprozil in presence of its alkaline induced Degradation Product a comparative study
    Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2015
    Co-Authors: Khalid A M Attia, Mohammed W I Nassar, Mohamed B Elzeiny, Ahmed Serag
    Abstract:

    Four simple, accurate and precise stability-indicating spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of Cefprozil (CZ) and its alkaline-induced Degradation Product (DCZ) without prior separation namely; ratio difference, mean centering, derivative ratio using Savitsky-Golay filter and continuous wavelet transform. The accuracy, precision and linearity ranges of the proposed methods were determined. The methods were validated and the specificity was assessed by analyzing synthetic mixtures containing the drug and its degradate. The four methods were applied for the determination of the cited drug in tablets and the obtained results were statistically compared with those of a reported method. The comparison showed that there are no significant differences between the proposed methods and the reported method regarding both accuracy and precision.

Khalid A M Attia - One of the best experts on this subject based on the ideXlab platform.

  • different mathematical spectrophotometric methods for determination of lesinurad in the presence of its oxidative Degradation Product
    Analytical Chemistry Letters, 2018
    Co-Authors: Khalid A M Attia, Ahmed Elolemy, Nasr M Elabasawi, Ahmed H Abdelazim
    Abstract:

    Lesinurad is a novel selective uric acid reabsorption inhibitor which has been recently approved for the treatment of the chronic gout. Four simple mathematical spectrophotometric methods have been developed for the quantitative and selective determination of lesinurad in the presence of its oxidative Degradation Product. Complete oxidative Degradation of lesinurad to its Degradation Product has been done. The developed methods namely, ratio difference spectrophotometric, first derivative of the ratio spectra, mean centering of the ratio spectra and continuous wavelet transform spectrophotometric methods. These methods have been developed and optimized to resolve the existed overlapping between the zero order UV absorption spectra of lesinurad and its oxidative Degradation Product. The described spectrophotometric methods have achieved selective determination of lesinurad without any interference from the oxidative Degradation Product. Also, they have been validated and applied for quantitative an...

  • second derivative spectrophotometric and synchronous spectrofluorometric determination of lesinurad in the presence of its oxidative Degradation Product
    New Journal of Chemistry, 2018
    Co-Authors: Khalid A M Attia, Ahmed Elolemy, Nasr M Elabassawi, Ahmed H Abdelazim
    Abstract:

    Lesinurad is a novel selective uric acid reabsorption inhibitor which has been recently approved for the treatment of chronic gout. The present study is considered to report the first analytical methods for the quantitative and selective determination of lesinurad in the presence of its oxidative Degradation Product. Complete oxidative Degradation of lesinurad has been done after extensive trials under different conditions. Identification of the lesinurad oxidative Degradation Product has been checked via mass spectrometry. Derivative mathematical manipulation has been introduced to resolve the overlap that existed between the recorded UV absorption spectra or the synchronous fluorescence spectra of lesinurad and its Degradation Product. The second derivative of the UV spectra has enabled the estimation of lesinurad by measuring the peak amplitudes at 279 nm without any interference from its Degradation Product. Alternatively, the second derivative of the synchronous fluorescence spectra has enabled the selective determination of lesinurad by measuring the peak amplitudes at 370 nm (Δλ = 60) nm without any interference from the Degradation Product. The developed methods have been optimized, validated and applied for quantitative determination of the studied drug in its pharmaceutical dosage form.

  • quantitative estimation and validation of rafoxanide in presence of its alkali induced Degradation Product by different spectrophotometric methods
    Journal of Advanced Pharmacy Research, 2018
    Co-Authors: Mohammed W I Nassa, Khalid A M Attia, Ahmad A Mohamad, Ragab A M Said, Ahmed H Abdelmonem
    Abstract:

    Objective: Development and validation of four simple, accurate, selective and sensitive UV spectrophotometric methodsfor the determination of rafoxanide in the presence of its alkali-induced Degradation Product without preliminary separation. Methods: (A) Dual wavelength method, where the difference in absorbance were calculated at 242 and 281 nm. (B) Area under the curve method,where area under the peak were measured at wavelength ranges (225-235 nm) and (275-295 nm). (C) Bivariate method, where the absorbance values were measured at selected wavelengths 250 and 280 nm. (D) First derivative method, whereThe amplitudes were measured at 253 nm. Results: Good linearity was found in the concentration range of 2.5–25 μg/mL for all the methods. The specificity of the methods were assessed by analysing synthetic mixtures containing the drug and its Degradation Product. Methods are validated as per ICH guidelines and accuracy, precision, repeatability and robustness are found to be within the acceptable limit. Conclusion: The proposed methods have been found to be accurate, precise and can be used for determination of the drug in pure form and pharmaceutical formulations as well as in the presence of its Degradation Product without any preliminary separation steps.

  • comparative study of different electrochemical sensors for determination of phenazopyridine hydrochloride in the presence of its computationally selected Degradation Product
    Analytical Chemistry Letters, 2017
    Co-Authors: Khalid A M Attia, Ahmed Elolemy, Nasr M Elabasawi, Ahmed H Abdelazim
    Abstract:

    AbstractStability-indicating potentiometric methods have been developed for determination of phenazopyridine hydrochloride (PAP) in the presence of its computationally selected Degradation Product. Density functional theory has been applied as a computational model to study the energy of PAP metabolites and the results revealed that 2, 3, 6- triaminopridine (TAP) has been the most stable Degradation Product. Design of PVC and coated graphite sensors has been based on the ion pair of PAP with phosphotungstic acid using dioctylphthalate as a plasticizer. Several significant parameters controlling the performance of the proposed sensors have been examined and optimized. Under the selected optimal conditions the proposed sensors exhibit Nernstian responses in the concentration range of 1.0×10-2 - 1.0×10-5 M with detection limits of 9 x10-6 and 9.6×10-6 M for PVC and coated graphite sensors respectively. Real-time monitoring of the Degradation of PAP to TAP has been achieved and the online data obtained showed...

  • comparative study between zero order spectra processing and ratio spectra manipulating methods applied for the determination of isoxsuprine hydrochloride in the presence of its oxidative Degradation Product
    Journal of AOAC International, 2017
    Co-Authors: Khalid A M Attia, Ragab A M Said, Ahmed Elolemy, Nasr M Elabassawi, Sherif Ramzy
    Abstract:

    Four accurate, precise, and validated stability-indicating spectrophotometric methods handling either zero-order spectra or ratio spectra have been developed and compared for the analysis of isoxsuprine hydrochloride (ISX) in the presence of its oxidative Degradation Product. The first two methods processed zero-order spectra, namely graphical absorbance ratio or Q-Analysis and area under the curve, whereas the third and fourth methods manipulated ratio spectra, namely the ratio difference spectrophotometric method and derivative ratio. The proposed methods showed good linearity in the range of 2-23 µg/mL. The methods were tested for specificity using laboratory-prepared mixtures containing the drug and its Degradation Product. The proposed methods were applied for the determination of ISX in Vascular tablets and the obtained results were acceptable, with small percentage RSD values. The validity of the proposed procedures was further assessed by applying the standard addition technique, which showed no interference from excipients. The obtained results were statistically compared with those obtained by the reported method, showing no significant differences when t- and F-tests were applied.

Nancy K. Wilson - One of the best experts on this subject based on the ideXlab platform.

Marsha K Morgan - One of the best experts on this subject based on the ideXlab platform.