Browsing by Author "El-Bagary R."

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A combination of isocratic and gradient elution modes in HPLC with the aid of time-overlapping process for rapid determination of methyldopa in human urine
(Taylor and Francis Inc., 2015) Emara S.; Masujima T.; Zarad W.; Kamal M.; Fouad M.; El-Bagary R.; Department of Pharmaceutical Chemistry; Faculty of Pharmacy; Misr International University; Km 28 Ismailia Road; Ismailia; Cairo; 41522; Egypt; P.I. Lab. Single Cell MS; RIKEN Quantitative Biology Center; Suita; Osaka; Japan; Department of Pharmaceutical Analytical Chemistry; Faculty of Pharmacy; Modern Sciences and Arts University; Cairo; Egypt; Department of Pharmaceutical Chemistry; Faculty of Pharmacy; Cairo University; Cairo; Egypt
A new rapid time-overlapping high-performance liquid chromatography method using coupled-column double-injection technique with fluorescence detection has been developed and validated to determine methyldopa (MTD) in human urine. The method was based on injecting a new sample onto the second column before finalizing the cleanup and the re-equilibration of the first column for the former sample. A combination of isocratic and gradient elution was employed according to a pre-set program. At the beginning, isocratic step of acetate buffer solution (0.1 M, pH 2.4) was set until 7 min. Subsequently, a gradient elution step using acetate buffer (0.1 M, pH 2.4) as mobile phase A and acetonitrile as mobile phase B was employed. After the end of each gradient step, the column was re-equilibrated with 4 mL of the starting isocratic elution system before the next analysis. The overall cycle time was 7 min per each sample. The calibration curve was linear over the concentration range of 0.1-40 ?g/mL MTD. The overall mean recoveries were in the range of 98.29-101.39%. The applicability of the method was successfully evaluated by monitoring the incremental urinary excretion of MTD in human urine over 12 hr after a single oral administration of 250 mg. � 2015 Taylor & Francis Group, LLC.
An eco-friendly direct injection HPLC method for methyldopa determination in serum by mixed-mode chromatography using a single protein-coated column
(Oxford University Press, 2015) Emara S.; Masujima T.; Zarad W.; Kamal M.; Fouad M.; El-Bagary R.; Pharmaceutical Chemistry Department; Faculty of Pharmacy; Misr International University; Km 28 Ismailia Road; Cairo; Egypt; P.I. Lab. Single Cell MS; RIKEN Quantitative Biology Center; 6-2-3; Furuedai; Suita; Osaka 565-0874; Japan; Pharmaceutical Analytical Chemistry Department; Faculty of Pharmacy; Modern Sciences and Arts University; 26 July Mehwar Road Intersection With Wahat Road; 6 October City; Egypt; Pharmaceutical Chemistry Department; Faculty of Pharmacy; Cairo University; Kasr El Aini St.; Cairo; 11562; Egypt
A simple, rapid and environment-friendly direct injection HPLC method for the determination of methyldopa (MTD) in human serum has been developed and validated. The method was based on cleanup and separation of MTD from serum by mixed-mode liquid chromatography using a single protein-coated TSK gel ODS-80 TM analytical column (50 x 4.0 mm i.d., 5 ?m). The protein-coated column exhibited excellent resolution, selectivity and functioned in two chromatographic modes: size-exclusion chromatography [i.e., solid-phase extraction (SPE) for serum proteins] and reversed-phase chromatography for the final separation of MTD. SPE and HPLC separation were carried out simultaneously with a green mobile phase consisting of acetate buffer (0.1 M, pH 2.4) at a flow rate of 1 mL/min and at room temperature (23 � 1�C). The eluent was monitored at emission and excitation wavelengths of 320 and 270 nm, respectively. A calibration curve was linear over the range of 0.1-30 ?g/mL with a detection limit of 0.027 ?g/mL. This online SPE method was successfully applied to real samples obtained from patients receiving MTD therapy. � The Author 2015. Published by Oxford University Press. All rights reserved.
On-line coupling of derivatization with pre-concentration to determine trace levels of methotrexate
(Xi'an Jiaotong University, 2013) Emara S.; Masujima T.; Zarad W.; Kamal M.; El-Bagary R.; Pharmaceutical Chemistry Department; Faculty of Pharmacy; Misr International University; Km 28 Ismailia Road; Cairo; Egypt; Analytical Molecular Medicine and Devices Laboratory; Hiroshima University; Graduate School of Biomedical Sciences; 1-2-3; Kasumi; Minami-ku; Hiroshima 734-8551; Japan; Pharmaceutical Analytical Chemistry Department; Faculty of Pharmacy; Modern Sciences and Arts University; 26 July Mehwar Road intersection with Wahat Road; 6 October City; Egypt; Pharmaceutical Chemistry Department; Faculty of Pharmacy; Cairo University; Kasr El Aini St.; Cairo 11562; Egypt
A new simple, sensitive and precise green analytical procedure using an automated packed-reactor derivatization technique coupled with on-line solid-phase enrichment (SPEn) has been developed and evaluated to determine trace levels of methotrexate (MTX). The method was based on injection of MTX into a flowing stream of phosphate buffer (0.04 M, pH 3.4), carried through the packed oxidant reactor of Cerium (IV) trihydroxyhydroperoxide for oxidative cleavage of the drug into highly fluorescent product, 2,4-diaminopteridine-6- carboxylic acid, followed by SPEn on a head of short ODS column (10 mm�4.6 mm i.d., 5 ?m particle size). The flow rate was 0.25 mL/min and packed reactor temperature was 40 �C. The trapped product was back-flush eluted from the ODS column to the detector by column-switching with an environmentally friendly mobile phase consisting of ethanol and phosphate buffer (0.04 M, pH 3.4) in the ratio of 5:95 (v/v). The eluent was monitored at emission and excitation wavelengths of 460 and 360 nm, respectively. The calibration curve was linear over the concentration range of 1.25-50 ng/mL with a detection limit of 0.08 ng/mL. The method was successfully applied to determine MTX in pharmaceutical formulations with mean percentage recovery ranging from 99.48 to 99.60. � 2013 Xi'an Jiaotong University.