Browsing by Author "Salem Rizk, Mohammed"

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Simultaneous Determination of Levonorgestrel and Ethinyl Estradiol in Combined Dosage form Utilizing Spectrophotometric Methods and High Performance Thin Layer Chromatographic Method on Nanosilica Gel Plates
(eurjchem, 2017) Moussa Tony, Rehab; Mohamed, Dalia; Sultan, Maha; Salem Rizk, Mohammed
Simultaneous quantification of levonorgestrel (LEV) and ethinyl estradiol (EE) was performed utilizing five different spectrophotometric methods and a high performance thin layer chromatographic method (HPTLC). The applied spectrophotometric methods were based on either ratio spectra namely; ratio difference, ratio subtraction and derivative ratio or the presence of isosbestic point specifically; absorbance subtraction and amplitude modulation. The proposed methods had the ability to resolve the overlapped spectra of the drugs with a linear relationship in the concentration range 1-65 µg/mL and 1-95 µg/mL for LEV and EE, respectively. The developed HPTLC method has revealed a good separation of the drugs upon utilizing Nano Silica Gel on TLC plates with fluorescent indicator 254 nm glass plates as the stationary phase and chloroform: methanol (99:1, v:v) as the mobile phase. The proposed HPTLC method has shown high sensitivity, where the linearity range was 0.02-3.00 µg/band and 0.5-20.0 µg/band, for LEV and EE, respectively. The proposed methods were successfully applied for the analysis of laboratory prepared mixtures as well as combined dosage form. Validation for all methods was conducted in compliance with the ICH guidelines proving the methods to be selective, linear, precise and accurate. The proposed methods were statistically compared with the pharmacopoeial method, where the obtained results showed no significant difference regarding accuracy and precision.
Simultaneous Spectrophotometric Determination of Paracetamol and Dantrolene Sodium by Chemometric Methods
(Journal of Pharmaceutical Research International, 2016) Salem Rizk, Mohammed; Sultan, Maha; Hassan Habib, Ibrahim; Mohamed, Dalia; Moussa Tony, Rehab
Aim: Simultaneous determination of Paracetamol (PAR) and Dantrolene Sodium (DAN) in pharmaceutical formulations was carried spectrophotometrically. Study Design: Two different chemometric techniques namely Partial Least-Squares (PLS) and Classical Least Squares (CLS). In both techniques, a full factorial experimental design was done using three levels and both components in mixtures. Methodology: This design was used to prepare the concentration data matrix in solvent composed of 2.5 mM NaOH solution. The wavelength range of 220 – 500 nm was chosen with the intervals of Δλ= 1 nm, through which the corresponding absorbance data matrix was measured. Both of the absorbance and concentration data matrices were used to obtain regression. The regression was used for the prediction of the unknown concentrations of PAR and DAN in their mixture. Neither chemical separation steps nor prior graphical treatment of the overlapped spectra was required for this procedure. Results: The linearity of calibration curve was fulfilled over concentrations of 1-20 and 1.5 – 15 μg/mL for PAR and DAN, respectively. Conclusion: Validation was done for multivariate methods using both authentic mixtures and pharmaceutical preparations. Assessment of accuracy and precision was done for each method and results were compared
Square-wave voltammetric determination of drospirenone and ethinylestradiol in pharmaceutical dosage form using square wave technique
(Atlanta Publishing House LLC, 2019) Hassan Habib, Ibrahim; Salem Rizk, Mohammed; Sultan, Maha; Mohamed, Dalia; Moussa Tony, Rehab
Cathodic voltammetric behaviors of drospirenone and ethinylestradiol were used for the simultaneous determination of both drugs in bulk and in pharmaceutical formulation (Yasmin® tablets) without the interference of excipients. The determinations were made on hanging mercury dropping electrode using square-wave technique in a voltammetric cell containing 10 mL of 0.04 mole/L Britton-Robinson. After every aliquot addition, the solution was stirred for 10 s at 1000 rpm, rested for 10 s then square wave voltammetry mode was ramped from +100 to -1700 mV with scan rate of 100 mV/s, pulse amplitude of 50 mV and measurement time of 5 ms. Several factors such as pH, type of supporting electrolyte, pulse amplitude and scan rate were studied to optimize the condition for voltammetric determination of these drugs. With optimized experimental parameters, a good linearity was obtained for both drugs over a range of 1.36×10-6 to 1.91×10-7 mole/L and 6.75×10-8 to 6.07×10-7 mol/L of drospirenone and ethinylestradiol, respectively. Characterization of the proposed method was done according to International Conference on Harmonization, Q2B: Validation of Analytical procedures. The proposed method was statistically compared with the reference method and the results revealed no significant difference regarding accuracy and precision.