University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Hassan Y. Aboul-Enein

Abbrev:
Aboul Enein, H.Y.
Other Names:
Address:
Bioanalytical and Drug Development Laboratory, Biological and Medical Research Department (MBC-03), King Faisal Specialist Hospital and Research Center, P.O. Box 3354, Riyadh 11211, Saudi Arabia
Phone:
(966-1) 422-7859
Fax:
(966-1) 442-7858

Citations 12

"Determination Of Nabumetone In Pharmaceutical Formulation By Flow Injection Analysis (FIA) With UV-detection"
Pharmazie 2003 Volume 58, Issue 1 Pages 22-24
Can, N. O.; Tuncel, M.; Aboul-Enein, H. Y.

Abstract: A precise and accurate FIA method for the quantification of nabumetone (NAB) in pharmaceuticals is described. The best suitable carrier solvent system consisted of ethanol: water (30:70 v/v). Sample solution (4.7 x 10^-6 M NAB) was prepared in this solvent and injected to the instrumental system at a flow rate of 1.2 mL min-1. The signals were detected by a UV detector at 228.8 nm. The calibration curves of NAB was linear in the concentration range of 1.4 x 10^-6 M-2.8 x 10^-5 M. The intra- and inter-assay precision were less than 2.6%. The method exhibited a good linearity with the correlation coefficients. The LOD and LOQ values were found to be 4.4 x 10^-7 and 1.3 x 10^-6 M, respectively. The effects of the tablet excipients were insignificant at the 95% probability level. The calculated tablet content was 99% which is agreement with the ranges stated by pharmacopoeias.

"Determination Of Fluoride In Toothpaste, Effluent Streams And Natural And Borehole Water Using A Flow Injection System With A Fluoride-selective Membrane Electrode"
Pharmaceut Acta Helv. 1999 Volume 73, Issue 6 Pages 307-310
Raluca-Ioana Stefan, Jacobus F. van Staden and Hassan Y. Aboul-Enein

Abstract: An automated system for the determination of fluoride in toothpaste, effluent streams, natural and borehole water based on the concept of flow injection with a fluoride-selective membrane electrode as sensor is described. The system is suitable for the on-line monitoring of fluoride at a sampling rate of 60 samples h-1 in the linear range 10^-4-10-1 (approximately 1.9-1900 mg l-1) with an RSD of better than 0.6%.

"Flow Injection System With Chemiluminometric Detection For Enzymatic Determination Of Ascorbic Acid"
Luminescence 2000 Volume 15, Issue 5 Pages 305-309
Andrei F. Dãnet, Mihaela Badea, Hassan Y. Aboul-Enein

Abstract: A simple, selective and rapid method for determination of ascorbic acid from fruit juices was developed by combining a flow injection analysis (FIA) system with a chemiluminometric detector and a reactor with L-ascorbate oxidase immobilized on controlled pore glass. It was found that some reducing agents (eg ascorbic acid and mercaptoacetic acid) give chemiluminescence with luminol in the presence of hexacyanoferrate (III) in an alkaline solution. We used this new type of chemiluminescent reaction for the enzymatic determination of ascorbic acid. The background substraction method was used in order to avoid interference during ascorbic acid determination. Accordingly, two chemiluminometric signals were registered for each determination, one signal corresponding to the sample that passed through the enzymatic reactor that decomposed the ascorbic acid completely, and the second signal corresponding to the sample that does not pass through the reactor. The difference between the two signals corresponds to ascorbic acid from the sample. The linear range of the method was 10^-1000 µmol/L of ascorbic acid and the detection limit was 5 µmol/L The throughput was four samples/h and RSD 3.13% (n = 10). This method was applied for determination of ascorbic in fruit juices. The results were compared with those found by the reference method, based on titrimetric determination with 2,6-dichlorophenolindophenol, and the concordance was excellent. Copyright
Ascorbic acid

"Rapid HPLC And Direct Flow Injection Analysis Assay For The Determination Of Trimetazidine HCl In Pharmaceutical Tablet Formulation"
J. Liq. Chromatogr. Relat. Technol. 2006 Volume 29, Issue 15 Pages 2245-2255
Göksel Altinodotokka; Kevser Kinodotrcalinodot; Hassan Y. Aboul-Enein

Abstract: A simple and sensitive high performance liquid chromatographic method (HPLC) and direct flow injection analysis method (FIA) are described for the determination of trimetazidine HCl (TMZ) in tablets. A mobile phase consisting of methanol:0.02 mol L -1 potassium dihydrogen phosphate: 0.005 mol L-1 sodium dihydrogen phosphate (62:5:33 v/v/v) was used for the resolution of the compound on a reversed phase column for HPLC. For the FIA method; the best solvent system was found to be consisting of methanol:water (10:90 v/v). A flow rate of l.2 mL min-1 was pumped and active material was detected at 210 nm. Limit of detection (LOD) and limit of quantitation (LOQ) values were found to be 1.2 x 10^-7 mol L-1 and 3.5 x 10^-7 mol L -1 , respectively, for HPLC. LOD and LOQ values were found to be 2.35 x 10^-7 mol L -1 and 7.04 x 10^-7 mol L-1 , respectively for FIA. The results obtained from the analysis of TMZ tablet formulations were comparable using both methods. Copyright © Taylor & Francis Group, LLC.

"A Validated Method Development For Ketoprofen By A Flow-injection Analysis With UV-detection And Its Application To Pharmaceutical Formulations"
Il Farmaco 2003 Volume 58, Issue 6 Pages 419-422
Hassan Y. Aboul-Enein, Arin Gul Dal and Muzaffer Tuncel

Abstract: A simple, sensitive and fast flow-injection analysis method with UV-detection method was developed for the determination of ketoprofen in pharmaceuticals. The standard and sample solutions were dissolved in a 10% ethanol which was suitable for this study. A flow-rate of 0.6 mL min-1 was used and the analyte was monitored at 260 nm. Variables such as concentrations, flow rate of reagents and other flow injection parameters were optimized to produce the most sensitive and reproducible results. Linear calibration curves were obtained in the range of 1.6 x 10^-6 and 1.7 x 10^-4 M. Limit of detection and limit of quantification were 1.7 x 10^-6 M (S/N=3.3) and 5.3 x 10^-6 M (S/N=10), respectively. The method was applied successfully to the analysis of ketoprofen pharmaceutical tablets. The recoveries were 102.75% for peak area and 98.42% for peak height. The proposed method is fast, precise, sensitive and easy to use for the determination of ketoprofen in pharmaceuticals.

"Flow Injection Methods Of Analysis For Waters. II. Organic Pollutants"
Crit. Rev. Anal. Chem. 2003 Volume 33, Issue 1 Pages 57-68
Andrei F. Dunec, Mihaela Cheregi, Jose Martinez Calatayud, Jose Vicente Garcia Mateo and Hassan Y. Aboul Enein

Abstract: A comprehensive, critical and updated review for the applications of flow-injection analysis (FIA) techniques for the analysis of organic pollutants in several types of water samples, except marine waters, is presented. The methods of indirect determination of organic pollutants in water by using flow injection coupled with atomic absorption spectroscopy are also discussed.
Environmental Spectrophotometry Review

"Flow Injection Methods Of Analysis For Waters. I. Inorganic Species"
Crit. Rev. Anal. Chem. 2001 Volume 31, Issue 3 Pages 191-222
Andrei. F. Danet, Mihaela Cheregi, Jose Martinez Calatayud, Jose Vicente Garcia Mateo and Hassan Y. Aboul Enein

Abstract: A comprehensive, critical, and an updated review of the applications of flow-injection analysis (FIA) techniques for the analysis of inorganic cations and anions in several types of water samples except marine waters is presented. The pre-concentration of metals in water samples and automaton of FIA systems for monitoring water quality are also discussed. The review is documented with 280 references.
Environmental Automation Preconcentration Review

"Recent Developments And Applications Of Chemiluminescence Sensors"
Crit. Rev. Anal. Chem. 2000 Volume 30, Issue 4 Pages 271-289
Hassan Y. Aboul-Enein, Raluca-Ioana Stefan, Jacobus F. van Staden, Xinrong R. Zhang, Ana M. Garcia-Campana and Willy R. G. Baeyens

Abstract: Chemiluminescence sensors are important tools in analytical chemistry due to their high sensitivity selectivity. This review presents the instrumentation involved in their design, including light detection and flow injection analysis system used. Various applications for the analysis of inorganic and organic compounds from gaseous samples and solutions indicate that these sensors are used with good reproducibility and selectivity of the analytes at low concentration level.
Chemiluminescence Sensor Sensor Sensor Review

"Chemiluminescence-based (bio)sensors - An Overview"
Crit. Rev. Anal. Chem. 1999 Volume 29, Issue 4 Pages 323-331
Hassan Y. Aboul-Enein, Raluca-Ioana Stefan and Jacobus F. van Staden

Abstract: This review discusses the advances in the design of chemiluminescence-based sensors and biosensors with particular emphasis on their classification. Several up-to-date applications are presented.
Environmental Chemiluminescence Sensor Review Immobilized reagent

"A Rapid, Sensitive High Performance Liquid Chromatographic Method For The Determination Of Meropenem In Pharmaceutical Dosage Form, Human Serum And Urine"
Biomed. Chromatogr. 2001 Volume 15, Issue 4 Pages 263-266
Yalcin Özkan, lkay Küçükgüzel, Sibel A. Özkan, Hassan Y. Aboul-Enein

Abstract: A new, simple, precise and rapid high performance liquid chromatographic method was developed for the determination of meropenem in human serum, urine and pharmaceutical dosage forms. Chromatography was carried out on an LC18 column using a mixture of 15 mM KH2PO4:acetonitrile:methanol (84:12:4; v/v/v), adjusted to pH 2.8 with H3PO4. The proposed method was conducted using a reversed-phase technique, UV monitoring at 307.6 nm and cefepime as an internal standard. The retention times were 5.98 and 7.47 min for cefepime and meropenem, respectively. The detector response was linear over the concentration range of 50-10,000 ng/mL. The detection limit of the procedure was found to be 22 ng/mL. The detection limit for meropenem in human plasma was 108.4 ng/mL and the corresponding value in human urine was 179.3 ng/mL. No interference from endogenous substances in human serum, urine and pharmaceutical preparation was observed. The proposed method is sufficiently sensitive for determination of the concentrations of meropenem and may have clinical application for its monitoring in patients receiving the drug.

"Flow Analysis For Determination Of Paraoxon With Use Of Immobilized Acetylcholinesterase Reactor And New Type Of Chemiluminescent Reaction"
Biopolymers 2000 Volume 57, Issue 1 Pages 37-42
Andrei F. Danet, Mihaela Badea, Jean-Louis Marty, Hassan Y. Aboul-Enein

Abstract: A highly sensitive flow analysis method for determination of acetylcholinesterase (AChE) inhibitors like organophosphorous pesticides using a new chemiluminescent reaction was developed and optimized. This method is fast, sensitive, and cheap, because it requires only one enzyme and its substrate. The system incorporates a reactor with immobilized AChE on controlled pore glass (CPG) and a chemiluminometric detector. Variations in enzyme activity due to inhibition are measured from the changes of concentrations of thiocholine produced when the substrate (acetylthiocholine chloride) is pumped before and after the passage of the solution containing the pesticide through the immobilized AChE reactor. Thiocholine is determined by a new chemiluminescent reaction with luminol in the presence of potassium ferricyanide. The percentage inhibition of enzyme activity is correlated to the pesticide concentration. The inhibited enzyme is reactivated by 10 mM pyridine-2-aldoxime methiodide (2-PAM). The experimental conditions were first optimized for activity determination of the effect of pH, flow rates, and Tris concentrations. For the measurement of AChE inhibition, the appropriate concentration of the substrate is selected such that the rate of noninhibited reaction can be considered unchanged and could be used as a reference. For optimization of experimental conditions for inhibition, several parameters of the system are studied and discussed: flow rate, enzyme-pesticide contact time, luminol concentration, ferricyanide concentration, 2-PAM concentration, and configuration of the FIA manifold. Paraoxon, an organophosphorous pesticide was tested. For an inhibition time of 10 min the calibration graph is linear from 0.1 to 1 ppm paraoxon with a relative standard deviation (n = 5) of 4.6% at 0.5 ppm. For an inhibition time of 30 min the calibration graph is linear from 25 to 250 ppb paraoxon.

"Determination Of Cefuroxime Axetil In Tablets And Biological Fluids Using Liquid Chromatography And Flow Injection Analysis"
Anal. Chim. Acta 2006 Volume 576, Issue 2 Pages 246-252
Nafiz Ö. Can, Göksel Altiokka and Hassan Y. Aboul-Enein

Abstract: Cefuroxime axetil is the pro-drug of cephalosporin cefuroxime that is used in the treatment of common community-acquired infections. A simple and precise liquid chromatographic method for the determination of cefuroxime axetil in pharmaceutical tablets, human serum and urine has been developed and validated. Cefuroxime axetil and indapamide (internal standard) were separated by a reversed phase column (Supelco Hypersil 5 ?m, 150 mm x 4.6 mm i.d., C18) using a mobile phase consisting of KH2PO4 (0.1 M) and acetonitrile (70:30 v/v) (at pH 4.0). The mobile phase was pumped at 1.0 mL min-1 flow rate and cefuroxime axetil was detected by ultraviolet detection at 281 nm within an average analysis time of 11 min. Flow injection analysis was performed for pharmaceutical tablet analysis using a carrier stream of methanol:water (10:90 v/v) with a flow rate of 1.0 mL min-1. The LOD and LOQ concentrations of the HPLC method were 1.35 x 10^-7 and 4.08 x 10^-7 M for the HPLC analysis and 1.31 x 10^-7 and 4.00 x 10^-7 M for FIA. The results of the analysis of the tablet formulation obtained by using these methods were statistically comparable with each other and with an additional spectrophotometric method. There was no significant difference between all these methods. © 2006 Elsevier B.V. All rights reserved.