Browsing by Author "Rashed N.S."

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Electrochemical determination of tolfenamic acid in bulk, tablets and urine
(Center of Excellence in Electrochemistry, Univ. of Tehran, 2017) Attia A.K.; Rashed N.S.; Fouad M.M.; Wasfy R.A.; National Organization for Drug Control and Research (NODCAR); Cairo; Egypt; Analytical Chemistry Department; Faculty of Pharmacy; Al-Azhar University; Cairo; Egypt; October University for Modern Sciences and Arts (MSA); Cairo; Egypt
A simple, precise, accurate and inexpensive voltammetric method was developed for the quantitative determination of tolfenamic acid at modified glassy carbon electrode in phosphate buffer of pH 7.2. Several factors such as type of buffer, type of surfactant; scan rate and accumulation time were studied to obtain the optimum conditions for the determination of tolfenamic acid. The proposed method shows linearity in concentration range of 6.0. 10-7-6.0. 10-6 mol L-1 with mean percentage recovery of 101.2. 1.99. The limits of detection and quantification were 1.43. 10-7 mol L-1 and 4.34. 10-7 mol L-1, respectively. The proposed voltammetric method was successfully applied to determine tolfenamic acid in pharmaceutical formulations and human urine. The results of the proposed method were statistically compared with those of a reported method and showed no significant difference. Thus, it can be used as quality control for this drug in laboratories.. 2017 by CEE (Center of Excellence in Electrochemistry).
Validated spectroscopic methods for the estimation of triamterene in bulk powder and capsule form via derivatization reactions
(John Wiley and Sons Ltd, 2018) Ibrahim F.A.; Fouad M.M.; Rashed N.S.; Fathy M.E.; Mahmoud E.S.; Department of Pharmaceutical Analytical Chemistry; Faculty of Pharmacy; University of Mansoura; Mansoura; Egypt; Department of Analytical Chemistry; Faculty of Pharmacy; October University for Modern Sciences and Arts; Cairo; Egypt; Department of Analytical Chemistry; Faculty of Pharmacy; Al-Azhar University; Cairo; Egypt
Sensitive, simple and specific spectrophotometric and spectrofluorimetric methods were developed for the determination of triamterene in bulk powder and pharmaceutical dosage form. The spectrophotometric method (Method A) is based on the formation of an ion-pair complex with eosin Y in acetate buffered solution of pH 3.7 followed by measuring the absorbance at 545 nm. The absorbance concentration plot is rectilinear over the range 3.0 15.0g/mL with a limit of detection (LOD) of 0.429 ?g/mL and a limit of quantitation (LOQ) of 1.031g/mL. The spectrofluorimetric method (Method B) is based on the reaction of triamterene with 7- chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) in basic solution (pH. 10) to form a product with high fluorescence measured at 546 nm after being excited at 438 nm. The plot of fluorescence versus concentration is linear within the range 2.0. 10.0g/mL. The suggested methods were applied for the analysis of commercial capsules containing the studied drug with successful results. The results obtained from the proposed method were statistically compared with those of a reported one and revealed good agreement. The presented methods are useful in routine analysis of triamterene in laboratories of quality control. � 2018 John Wiley & Sons, Ltd.
Validated ultra-performance liquid chromatographic and thin-layer chromatographic densitometric methods for the determination of paracetamol, pamabrom, and pyrilamine maleate
(Akademiai Kiado Rt., 2018) Rashed N.S.; Ibrahim F.A.; Fouad M.M.; Mahmoud E.S.; Analytical Chemistry Department; Faculty of Pharmacy; Al-Azhar University; Egypt; Pharmaceutical Analytical Chemistry Department; Faculty of Pharmacy; Mansoura University; Egypt; Analytical Chemistry Department; Faculty of Pharmacy; Al-Azhar University; October University for Modern Sciences and Arts; Egypt
Two chromatographic methods were developed for the simultaneous determination of paracetamol, pamabrom, and pyrilamine maleate in bulk and combined pharmaceutical dosage form. The first method is an ultra-performance liquid chromatographic (UPLC) method, in which separation was carried out by gradient elution using C18 column and a mobile phase composed of solution A (acetonitrile) and solution B (phosphate buffer) (pH 3.5). The elution started with 20% (by volume) acetonitrile ramped up linearly to 100% in 2 min, then kept constant till the end of the run at a flow rate of 1.5 mL min?1 and ultraviolet (UV) detection at 277 nm. The second method depends on the densitometric determination of thin-layer chromatograms of the three drugs. Separation was carried out at 275 nm using chloroform?acetonitrile (15:35, v/v) as the mobile phase. The proposed methods were validated according to the International Conference on Harmonisation (ICH) guidelines. Beers law was obeyed in the range of 5100 ?g mL?1 for paracetamol and 0.520 ?g mL?1for pamabrom and pyrilamine maleate, respectively, with mean recoveries of 98.40?100.32% 0.551?0.771 for the UPLC method. Linearity of the thin-layer chromatographic method was achieved in the range of 10?280, 5?45, and 120 ng per spot of the three drugs with mean recoveries of 98.75?100.30% 0.971?1.061, respectively. The two methods were successfully applied for the simultaneous determination of the cited drugs in their laboratory-prepared mixtures and pharmaceutical dosage form with good accuracy and precision. The results obtained were compared with those of the reported method and found to be in good agreement. Akadmiai Kiad, Budapest.