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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Jamal A. Sweileh

Abbrev:
Sweileh, J.A.
Other Names:
Address:
Department of Chemistry, Al al-Bayt University, PO Box 130040, Almafraq, Jordan
Phone:
+974-485-2196
Fax:
+974-485-1049

Citations 7

"Phosphate Rock Treatment With Citric Acid For The Rapid Potentiometric Determination Of Fluoride With Ion-selective Electrode"
Talanta 2000 Volume 51, Issue 5 Pages 993-999
Atef O. Al-Othman and Jamal A. Sweileh

Abstract: A fast method for sample treatment of phosphate rock has been developed for the purpose of quantitative leaching (98-100%) of fluoride but less of the interfering cations such as iron and aluminum. Citric acid (0.5 M) was used to extract fluoride in 15-45 min. Leaching of iron and aluminum is minimal, and these ions are complexed with citric acid. The leaching method was optimized with respect to sample size, citric acid concentration, leaching time and temperature. The analysis was completed by the rapid determination of fluoride with ion-selective electrode. The proposed treatment method was applied to phosphate rock samples from Jordan and Morocco and yielded accurate results as compared to the standard steam distillation from strong acid solution followed by thorium nitrate titration.

"On-line Flow Injection Solid Sample Introduction Digestion And Analysis: Spectrophotometric And Atomic Absorption Determination Of Iron, Copper And Zinc In Multi-vitamin Tablets"
Microchem. J. 2000 Volume 65, Issue 1 Pages 87-95
Jamal A. Sweileh

Abstract: An on-line flow injection system with solid sample introduction, digestion, treatment and analysis was proposed. The solid sample powder is inserted into a special chamber and carried by the digestion solution to a thermally heated PVC coil (1.4 mm i.d,). The analyte metal as the chloro-complex was retained on a coarse-particle (> 0.5 mm) anion exchange resin mini column. The resin beads are held between two plastic screens which allow insoluble residue to pass through to waste. After a brief column wash, the analyte is eluted with diluted HNO3 and determined spectrophotometrically or by atomic absorption. The proposed novel configuration of the multi-channel pinch valve allows handling slurries without tube blockage or valve damage. The system performance was tested by the determination of Fe, Zn and Cu in multi-vitamin tablets. Fe was determined spectrophotometrically as the thiocyanate complex while Zn and Cu were determined by atomic absorption. Compared with conventional digestion and analysis procedures the flow system yields a reasonably accurate relative error(RE) <2% and precise results with relative standard deviation (RSD) in the range of 2.5-4.2%.
Stopped-flow

"On-line Flow Injection Solid Sample Introduction, Leaching And Potentiometric Determination Of Fluoride In Phosphate Rock"
Anal. Chim. Acta 2007 Volume 581, Issue 1 Pages 168-173
Jamal A. Sweileh

Abstract: A flow injection method with on-line solid sample dissolution was developed for the determination of fluoride in phosphate rock. The fluoride was selectively leached (98-102.4% recovery) from a 50 mg powdered phosphate rock sample with 0.50 M citric acid. Using the zone sampling technique the fluoride in the buffered leachate was determined by injecting 87 µL into the carrier stream using a fluoride ion-selective electrode detector. The sensing element of the electrode was housed in a home-made sleeve-type flow-through cell. On-line solid sample digestion with 0.50 M citric acid at 55°C resulted in minimum dissolution of interfering iron and aluminum ions with improved accuracy and calibration linearity. The incorporation of relatively high level of fluoride in the carrier stream (40 ?g mL-1) facilitated the determination of high levels of fluoride in phosphate rock (up to 4.1%) with out the need for excessive on-line dilution. The optimized flow system was applied for the determination of fluoride in phosphate rocks samples and a reference material at a rate of nine samples per hour with a relative standard deviation (n = 5) of 2.95-4.0 %. Comparison of the proposed flow injection method with the standard method, which involves steam distillation from sulfuric acid solution and manual titration with thorium nitrate, showed no evidence of bias at the 95% confidence level. © 2006 Elsevier B.V. All rights reserved.

"On-line Elimination Of Spectral Interference Of Iron Matrix In The Flame Atomic Absorption Determination Of Zinc By Anion-exchange Separation"
Anal. Chim. Acta 2004 Volume 523, Issue 2 Pages 287-292
Jamal A. Sweileh and Eman M. El-Nemma

Abstract: A flow injection analysis (FIA) system has been developed for the flame atomic absorption spectroscopic (FAAS) determination of zinc in iron matrix. The spectral line interference of iron at 213.859 nm was eliminated by on-line separation using a micro-column of strong anion-exchange resin (Dowex 1-X8). The zinc chloro complexes were retained from 2 M HCl solution while most of the iron chloro complexes were passed to waste. For a 2% iron solution, matrix removal efficiency was 98.2% which means that positive spectral line interference of iron at the Zn line was reduced from 0.42 to 0.008 µg mL-1 Zn. The optimized flow injection system can handle up to 48 samples with good precision (less than 3.5% relative standard deviation (RSD)) in the working range of 0.075-2.2 µg mL-1 Zn. Comparative analysis of a certified reference material and synthetic sample solutions containing traces of Zn in 2% Fe by the proposed method and by graphite furnace atomic absorption spectroscopy (GFAAS) showed no evidence of analytical bias at the 95% confidence level.

"On-line Dissolution Of Borate Melt For Simultaneous Matrix Isolation, Concentration And Flame Atomic Absorption Determination Of Lead In Phosphate Rock"
Anal. Chim. Acta 2001 Volume 448, Issue 1-2 Pages 151-156
Jamal A. Sweileh

Abstract: A previously developed on-line flow injection system for solid sample dissolution is described for matrix isolation, concentration and determination of lead in phosphate rock borate melt with flame atomic absorption spectroscopy (FAAS) detection. The flow system can handle slurries and allow solid sample digestion, simultaneous matrix isolation and analyte concentration. Various flow parameters were optimized including, sample size, flow rate, pH and buffer composition. Compared with direct determination by FAAS, the proposed method resulted in almost total elimination of matrix effect and a 15-fold increase in detectability. Ten samples per hour can be processed and analyzed for lead with a detection limit of 0.13 µg g-1 using simple equipment and a flame atomic absorption spectrometer. The analytical results obtained by the proposed method compared favorably with those obtained by mixed-acid digestion of the phosphate rock and graphite furnace atomic absorption spectroscopy (GFAAS).

"Study Of Equilibria In Cyanide Systems By Gas Diffusion Measurement Of Hydrogen Cyanide"
Anal. Chim. Acta 1996 Volume 336, Issue 1-3 Pages 131-140
Jamal A. Sweileh

Abstract: Speciation of hydrogen cyanide in different metal-cyanide systems at the µg mL-1 level was established by the selective measurement of hydrogen cyanide (HCN) diffused through a microporous Teflon membrane under thermodynamic equilibrium conditions. The test solution was continuously aspirated through the donor side of the gas diffusion unit until equilibrium was achieved with the stagnant buffer solution on the receptor side. The final assay of HCN was carried out spectrophotometrically (chloramine-T/barbiturate/isonicotinate) in the flow injection mode. The theoretical relation between the enrichment factor and the pH of the donor and receptor solutions was derived and experimentally verified. As confirmed by calculation the speciation of HCN can be established for simple soluble cyanides and cyanide complexes with log formation constants as high as 20. For more stable cyanide complexes the results are satisfactory; but for the highly stable hexacyanoferrate(III) this method is not feasible. The speciation of cyanide in metal-cyanide systems was studied by measuring the HCN concentration using a gas diffusion cell incorporated into a flow injection spectrophotometric system. The metal-cyanide test solution was pumped (2 ml/min) through the donor channel of the gas diffusion cell for 6 min until equilibrium was reached. During this period the acceptor solution, 0.1 M NaH2PO4 of pH 7, was kept stationary. At the end of the sampling period, the acceptor solution was injected into a carrier stream (0.4 ml/min) of 0.1 M NaH2PO4 of pH 7 and merged with 0.01% chloramine-T (0.4 ml/min) and sodium barbiturate/sodium isonicotinate reagent (1.6 ml/min). The mixture was heated to 68°C and propelled to the detection cell where the absorbance was monitored at 600 nm. The acceptor and donor channels of the gas diffusion cell had volumes of 0.108 mL. The apparatus was calibrated with 0.1-1 µg/ml NaCN. The calibration graph was linear, the detection liwas 0.025 ng/ml and the RSD (n = 9) for 0.5 µg/ml cyanide was 0.6%. The method was applied to metal-cyanide complexes at various pH values from 2-11. At each pH the concentration of each species was calculated using two mass balance equations, one for total cyanide and the other for total metal. 19 References
Hydrogen cyanide Spectrophotometry Gas diffusion Teflon membrane Speciation Titrations Equilibrium constants Heated reaction

"Determination Of Cyanide And Thiocyanate By A Spectrophotometric Flow Injection Method"
Anal. Chim. Acta 1989 Volume 220, Issue 1 Pages 65-74
Jamal A. Sweileh

Abstract: The described two-step flow injection method involved the complexation of CN- with Ni(II) in citric acid solution followed by the determination of SCN- by oxidation with chloramine-T buffer solution (pH 5.5±0.05) to ClCN, and reaction with Na isonicotinate - Na barbiturate reagent at 65°C to form a blue complex, the absorbance of which was measured at 600 nm. To determine CN- plus SCN-, the above procedure was repeated with a Ni-free citric acid solution and the CN- concentration. was calculated by difference. The pH, temperature and Ni(II) concentration. were optimized. Calibration graphs were rectilinear up to 2.5 and 5 µg mL-1 of CN- and SCN-, respectively, and the corresponding detection limits were 0.05 and 0.08 µg mL-1. Chloride, S-, AgI, Co(II) and Ni(II) ions interfered. The procedure was applied to synthetic solution; results were in good agreement with those obtained by the ASTM method. The throughput was 10 h-1.
Thiocyanate ion Cyanide Spectrophotometry Buffer Interferences Heated reaction Method comparison Standard method