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
Website: @unf

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Classification: Alloy

Citations 16

"Contribution To The Study Of The Solid-state Reaction Of Mercury With Pure Rhodium"
J. Therm. Anal. Calor. 2000 Volume 59, Issue 3 Pages 617-624
E. Milaré, F. L. Fertonani, A. V. Benedetti, M. Ionashiro

Abstract: Thermogravimetry (TG) and other analysis techniques (EDX, SEM, Mapping surface, X-ray diffraction, inductively coupled argon plasma emission spectroscopy and atomic spectrometry with cold vapor generation) were used to study the reaction of Hg with Rh. The results permitted the suggestion that, when subjected to heat, an electrodeposited Hg film reacts with Rh to form intermetallic products with different stabilities, as indicated by at least three mass loss steps. In the first step, between room temperature and 160°C, only the bulk Hg is removed. From this temperature up to about 175°C, the mass loss can be attributed to the desorption of a film of metallic Hg. The last step, from 175 to 240°C, can be ascribed to the removal of Hg from a thin dark film of RhHg2.
Mercury Spectrophotometry

"Simultaneous Kinetic Determination Of Cobalt, Nickel And Iron By Coupling Stopped-flow Techniques And Charge Coupled Device Detection"
Anal. Chim. Acta 2000 Volume 423, Issue 2 Pages 277-286
M. I. Karayannis and I. A. Pettas

Abstract: Two kinetic approaches were applied for the simultaneous determination of cobalt, nickel, and iron with multiple linear regression (MLR) method, using the entire kinetic curves or the initial rates of the reaction. The predictive ability of MLR method is based on the slight kinetic differences of these metals which occur at a great number of wavelengths when they react with xylenol orange as a common ligand. The reactions were monitored using a charge coupled device (CCD) UV-VIS spectrophotometer attached to a stopped-flow system. This instrumentation allowed to obtain kinetic data at a maximum of 2048 wavelengths simultaneously. The method was successfully applied to the simultaneous determination of these metals in alloys and the results obtained from the two kinetic approaches were compared.
Cobalt Nickel Iron Spectrophotometry Kinetic Method comparison Simultaneous analysis Stopped-flow Rate constants

"Application Of Artificial Neural Networks In Multifactor Optimization Of An On-line Microwave FIA System For Catalytic Kinetic Determination Of Ruthenium (III)"
Talanta 2001 Volume 54, Issue 4 Pages 603-609
Yi-Bo Zeng, Hong-Ping Xu, Hui-Tao Liu, Ke-Tai Wang, Xing-Guo Chen, Zhi-De Hu and Bo-tao Fan

Abstract: A methodology based on the coupling of experimental design and artificial neural networks (ANNs) is proposed in the optimization of a flow injection system for the spectrophotometric determination of Ru (III) with m-acetylchlorophosphonazo (CPA-mA), which has been for the first time used for the optimization of high-performance capillary zone electrophoresis (J. Chromatogr. A 793 (1998) 317). And since it has been applied in many other regions like micellar electrokinetic chromatography, ion-interaction chromatography, HPLC, etc. (J. Chromatogr. A 850 (1999) 345; J. Chromatogr. A 799 (1998) 35; J. Chromatogr. A 799 (1998) 47). An orthogonal design is utilized to design the experimental protocol, in which five variables are varied simultaneously (Anal. Chim. Acta 360 (1998) 227). Feedforward-type neural networks with extended δ-bar-δ (EDBD) algorithm are applied to model the system, and the optimization of the experimental conditions is carried out in the neural network with 5-5-1 structure, which have been confirmed to be able to provide the maximum performance. In contrast to traditional methods, the use of this methodology has advantages in terms of a reduction in analysis time and an improvement in the ability of optimization. Under the optimum experimental conditions, Ru (III) can be determined in the range 0.040 0.60 µg mL-1 with detection limit of 0.03 µg mL-1 and the sampling frequency of 34 h-1. The method has been applied to the determination of Ru (III) in refined ore as well as in secondary alloy and provided satisfactory results. (C) 2001 Elsevier Science B.V. All rights reserved.
Ruthenium(III) Spectrophotometry Neural network Optimization

"Flow Injection Systems With Inductively-coupled Argon Plasma Atomic Emission Spectrometry. 2. The Generalized Standard Addition Method"
Anal. Chim. Acta 1983 Volume 145, Issue 1 Pages 169-178
E. A. G. Zagatto, A. O. Jacintho, F. J. Krug and B. F. Reis

Abstract: In multicomponent analysis by inductively-coupled argon plasma emission spectrometry, the generalized standard addition method is useful in overcoming matrix and/or spectral interferences. As this method requires many standard additions, it becomes cumbersome when done manually if many elements are to be determined. By using a flow injection system, the standard addtion manipulations required can be significantly simplified and completed within a shorter period of time with much less sample material. A flow injection system with merging zones is used to demonstrate the method for analyzes of a Ni/Cu/Zn standard and of alloys. The reproducibility of measurements of the injected sample, with or without additions of standards is always better than 99%. The results obtained compare well with those obtained by the manual procedure and also with those obtained by atomic absorption spectrometry.
Copper Nickel Zinc Spectrophotometry Merging zones Standard additions calibration

"Simultaneous Flow Injection Determination Of Aluminum And Zinc Using LED Photometric Detection"
Anal. Chim. Acta 1990 Volume 230, Issue 1 Pages 125-130
Marek Trojanowicz and Joanna Szpunar-obiska

Abstract: The sample solution was injected into a carrier stream of 0.4 M acetate buffer (pH 4.5) that was then blended with aqueous 0.05% xylenol orange and passed through a reaction coil before detection in a 1.5-cm path-length flow cell by sequential operation of light-emitting diodes with emission max. at 563, 580 and 638 nm under computer control so that separate peak heights for the two analytes could be obtained by multiple linear regression with matrix inversion. Rectilinear calibration graphs were obtained for 0.2 to 25 µg mL-1 of Al and 0.2 to 30 µg mL-1 of Zn, and each could be determined in the presence of a 100-fold concentration. of the other. Several metals and anions interfered; interference from Fe(III) was minimized by reduction with ascorbic acid and masking with EDTA. The method was applied to alloys.
Aluminum Zinc Spectrophotometry Computer Buffer pH Flowcell Calibration Interferences Light emitting diode

"Flow Injection Extraction-spectrophotometric Method For The Determination Of Lead And Its Combination With Minicolumn Preconcentration"
Anal. Chim. Acta 1990 Volume 230, Issue 1 Pages 157-162
E. A. Novikov, L. K. Shpigun and Yu. A. Zolotov

Abstract: Two flow injection systems were devised, one without and one with ion-exchange pre-concentration. [2-mm-i.d. glass column of Chelex-100 resin (NH4+ form; 50 to 100 mesh)]. The Pb(II) was extracted from an aqueous HNO3 carrier stream into dicyclohexano-18-crown-6 solution in CHCl3 in a PTFE coil (2 m x 0.5 mm), and after phase separation in a membrane separator the CHCl3 layer was treated with 0.002% dithizone - 0.4% triethanolamine solution in CHCl3 (mixing ratio 3:2) in a 30-cm PTFE reaction coil for absorbance measurement at 512 nm. With ion-exchange pre-concentration. for 79 s, the calibration graph was rectilinear in the range 10 to 200 µg l-1, the detection limit was 5 µg L-1 and the coefficient of variation at 100 µg L-1 was 9% (n = 4). Test applications to analyzes of alloys, soil extracts and seawater are described briefly.
Lead Ion exchange Spectrophotometry Sample preparation Chelex Chelation Resin Crown ether Extraction Column Preconcentration Phase separator Membrane Calibration Detection limit Organic phase detection Dithizone

"Preconcentration Of Iron(III), Cobalt(II) And Copper(II) Nitroso-R Complexes On Tetradecyldimethylbenzylammonium Iodide-naphthalene Adsorbent"
Talanta 1995 Volume 42, Issue 3 Pages 337-344
Bal K. Puri and Sanjay Balani

Abstract: Iron, cobalt and copper form colored water soluble anionic complexes with disodium 1-nitroso-2-naphthol-3-6-disulphonate (nitroso R-salt). The anionic complex is retained quantitatively as a water insoluble neutral ion associated complex (M-nitroso R-TDBA) on tetradecyldimethylbenzylammonium iodide on naphthalene (TDBA+I--naphthalene) packed column in the pH range of: Fe(III): 3.1-6.5, Co: 3.4-8.5 and Cu 5.9-8.0 when their solutions are passed individually over this adsorbent at a flow rate of 0.5-5.0 ml/min. The solid mass consisting of an ion associated metal complex along with naphthalene is dissolved out of the column with 5 mL dimethylformamide/chloroform and metals are determined spectrophotometrically. The absorbance is measured at 710 nm for iron, 425 nm for cobalt and 480 nm for copper. Beers law is obeyed in the concentration range 9.2-82 µg of iron, 425 nm for cobalt cobalt and 3.0-62 µg of copper in 5 mL of final DMF/CHCl3 solution. The molar absorptivities are calculated to be Fe: 7.58 x 10^3, Co: 1.33 x 10^4 and Cu: 4.92 x 10^4 M 1 cm-1. Ten replicate determinations containing 25 µg of iron, 9.96 µg of cobalt and 3.17 µg of copper gave mean absorbances 0.677, 0.450 and 0.490 with relative standard deviations of 0.88, 0.98 and 0.92%, respectively. The interference of large number of metals and anions on the estimations of these metals has been studied. The optimized conditions so developed have been employed for the trace determination of these metals in standard alloys, waste water and fly ash samples.
Cobalt(II) Copper(II) Iron(III) Spectrophotometry Preconcentration

"Hydrogen Chromate PVC Matrix Membrane Sensor For Potentiometric Determination Of Chromium(III) And Chromium(VI) Ions"
Talanta 1996 Volume 43, Issue 5 Pages 797-804
Saad S. M. Hassana,*, M. N. Abbasb and G. A. E. Moustafab

Abstract: A novel potentiometric Cr6+ PVC matrix membrane sensor incorporating nickel tris(1,10-bathophenanthroline) hydrogen chromate as an electroactive material and 2-nitrophenyl phenyl ether as solvent mediator is described. In a phosphate buffer solution of pH 5, the sensor displays a rapid and linear response for Cr(VI) over the concentration range 2 x 10^-2 - 8 x 10^-6 M with an anionic slope of 55.5±0.2 mV decade-1 and a detection limit of the order of 0.4 µg mL-1. The sensor is used for sequential determination of Cr(VI) and Cr(III) by direct monitoring of Cr(VI) followed by oxidation of Cr(III) and measurement of the total chromium. The average recoveries of Cr(III) and Cr(VI) at concentration levels of 0.5-50 µg mL-1 are 99.1±0.4% and 99.1±0.4%, respectively. Redox and precipitation titrations involving Cr(VI) as titrant are monitored with the sensor. Cr(III) and/or Cr(VI) in wastewaters of some industries (e.g., leather tanning, electroplating, aluminum painting) and the chromium contents of some alloys and refractory bricks are assessed. The results agree fairly well with data obtained using the standard diphenylcarbazide spectrophotometric method.
Chromium(III) Chromium(VI) Potentiometry Electrode Electrode Sensor Speciation Redox Method comparison

"Catalytic Kinetic Simultaneous Determination Of Iron, Silver And Manganese With The Kalman Filter By Using Flow Injection Analysis Stopped-flow Spectrophotometry"
Talanta 1998 Volume 45, Issue 6 Pages 1123-1129
Ying-Zhi Ye*, Hong-Yan Mao and Ya-Hua Chen

Abstract: A catalytic differential kinetic method with Kalman filter for the simultaneous determination of multi-component is described. The oxidation of Rhodamine B (RB) by K periodate in a slightly acid solution is a slow reaction. But Fe(III), Ag(I) or Mn(II) has a differential catalytic effect on the oxidation reaction of RB in the presence of 1,10-phenanthroline as the activator. So Fe, Ag and Mn can be simultaneously determined by measuring the decreasing absorbance of the dye (RB) at 555 nm. A flow injection analysis stopped-flow spectrophotometric system with a microcomputer performs the determinations This method was applied to determining Fe, Ag and Mn in alloy samples with satisfactory results.
Iron(III) Silver(I) Manganese(II) Spectrophotometry Kalman filter Catalysis Kinetic Simultaneous analysis Stopped-flow Computer Indirect Multicomponent

"Determination Of Trace Amounts Of Aluminum By Ion Chromatography With Fluorescence Detection"
Analyst 1988 Volume 113, Issue 4 Pages 641-644
Phil Jones, Les Ebdon and Tim Williams

Abstract: A sample solution (adjusted to pH 4 with dilute HNO3) was injected via a 100 µL loop on to a cation-exchange guard column (5 cm) of Dionex CG2 at 50°C; the mobile phase was 0.10 M K2SO4 (adjusted to pH 3.0 with dilute HNO3). Post-column derivatization was performed with 2 mM 8-hydroxyquinoline-5-sulfonate (adjusted to pH 8.3 with dilute aqueous NH3), with fluorimetric detection at 512 nm (excitation at 360 nm). The calibration graph was rectilinear from 5 µg L-1 to 10 mg L-1 of Al, and the detection limit was 1 µg L-1 of Al. A typical coefficient of variation was 3.4% (n = 8) at 0.25 mg L-1 of Al. Other commonly occurring metals did not interfere. The method was used to determine Al in a reference alloy and in tap water.
Aluminum HPIC Fluorescence Interferences Post-column derivatization Reference material 8-hydroxyquinoline-5-sulfonic acid Heated reaction

"Spectrofluorimetric Flow-through Sensor For The Determination Of Beryllium In Alloys"
Analyst 1991 Volume 116, Issue 1 Pages 81-83
M. de la Torre, F. Fernández-Gámez, F. Lázaro, M. D. Luque de Castro and M. Valcárcel

Abstract: Samples were dissolved in HNO3 and diluted to give a concentration. of Be in the range 1 to 40 ppb, and EDTA was added to give a concentration. of 10 mM. A 1 mL portion of this solution was injected into a single channel flow injection manifold through which an eluent stream (consisting of a mixture of 20 mM HNO3, 20 mM NaNO3 and 20 ppb of morin) carried the sample plug to the flow cell (Hellma Model 176.052 QS). The resin exchanger (Dowex 1X4-100) was located in the flow cell, and the transient fluorescent signal was measured. The calibration graph was rectilinear and the coefficient of variation was 1.7% for 20 ppb (n = 11); the sampling frequency was 30 h-1.
Beryllium Fluorescence Sensor Resin

"Multicomponent Analysis By Flow Injection Using A Partial Least-squares Model. Determination Of Copper And Zinc In Serum And Metal Alloys"
Analyst 1996 Volume 121, Issue 2 Pages 169-172
Oscar Hernández, Francisco Jiménez, Ana Isabel Jiménez and Juan José Arias

Abstract: Sample (192 µL) was injected into a carrier stream (1.75 ml/min) which had been previously merged with a stream of 0.1 M borate buffer of pH 9 and also with a reagent stream of aqueous 10% methanolic 0.1 mM 4-(4'-methyl-2'-thiazolylazo)-2-methylresorcinol. The mixture was passed through a 80 cm reactor after which the absorption spectra were recorded from 520-620 nm at 1 s intervals for 40 s on a Hewlett-Packard 8452 A spectrophotometer, equipped with a diode-array detector, using an integration time of 0.4 s. A partial least-squares multivariate calibration method, employing the computer program Unscrambler, was used to process the data obtained (details given), thus enabling the simultaneous determination of Cu and Zn to be achieved. The results obtained agreed with those obtained by AAS.
Copper Zinc Spectrophotometry Partial least squares Method comparison Multivariate calibration

"Simultaneous Spectrofluorimetric Determination Of Selenium(IV) And (VI) By Flow Injection Analysis"
Analyst 1997 Volume 122, Issue 3 Pages 221-226
M. J. Ahmed, C. D. Stalikas, P. G. Veltsistas, S. M. Tzouwara-Karayanni and M. I. Karayannis

Abstract: A sample (100 µL) was injected into a carrier stream of 2 M H2SO4 at a flow rate of 0.1 ml/min and mixed with a reagent stream of 0.2 mM 2-(α-pyridyl)thioquinaldinamide in propan-2-ol at a flow rate of 0.3 ml/min. The fluorescence intensity due to Se(IV) was measured at 500 nm (excitation at 350 nm). A second portion (100 µL) was then injected into the carrier stream and passed through a coil (40 cm x 0.8 mm i.d.) where it was irradiated at 254 nm. The irradiated sample stream was then mixed with the reagent stream and the fluorescence intensity due to total Se was measured. Se(VI) was determined from the difference in the two fluorescence intensity values. The calibration graphs were linear from 0.01-2.2 and 0.1-2.4 µg/ml Se(IV) and Se(VI), respectively; corresponding detection limits were 1 and 10 ng/ml. RSD were 0.1-2% (n=5). The throughput was 25 samples/h. The method was applied to the analysis of alloys, hair, tap and lake water, sediments, soil, tea, flour and eggs. A simple, sensitive, highly selective, automatic spectrofluorimetric method for the simultaneous determination of selenium (IV) and (VI) as selenite-selenate by flow injection analysis (FIA) has been developed. The method is based on the selective oxidation of the non-fluorescent reagent 2-(α-pyridyl)thioquinaldinamide (PTQA) in acidic solution (1.5-3.0 M H2SO4) by Se(IV) to give an intensely fluorescent oxidation product (lambda ex =350 nm; lambda em = 500 nm). Selenium (VI) is reduced online to Se(IV), in a reduction coil installed in a photo- reactor, which is then treated with PTQA and the fluorescene due to the sum of Se(IV) and Se(VI) is measured; Se(Vi) is determined from the difference in fluorescence values. Various analytical parameters, such as effect of acidity, flow rate, sample size, dispersion coefficient, temperature, reagent concentration and interfering species were studied. The photo-reduction conditions were optimized, with an FIA procedure, for Se(VI) on the basis of its reduction efficiency. The calibration graphs were rectilinear for 0.1-2.4 µg mL-1 of Se(VI) and 10 ng mL-1 - 2.2 µg mL-1 of Se(IV), respectively. The method was applied to the determination of Se in several Standard Reference Materials (alloy, sediments and tea), as well as in some environmental waters (tap and surface water), food samples (flour and egg), a biological sample (human hair), soil sample and in synthetic mixtures. Up to 25 samples per hour can be analyzed with an RSD approximately 0.1-2%.
Selenium(IV) Selenium(VI) Fluorescence Speciation Photochemistry Selectivity Reference material Interferences

"Determination Of Arsenic In An Organic Phase By Coupling Continuous-flow Extraction - Hydride Generation With Inductively Coupled Plasma Atomic-emission Spectrometry"
J. Anal. At. Spectrom. 1989 Volume 4, Issue 7 Pages 581-585
Alberto Menéndez García, J. Enrique Sánchez Uría and Alfredo Sanz-Medel

Abstract: Arsenic is extracted (as AsI3) from sample solution into xylene in the presence of KI and HCl, and the extract is mixed with NaBH4 in DMF and acetic acid in a continuous-flow apparatus. The mixture is passed through a gas - liquid separator, and AsH3 is determined by ICP-AES at 228.81 nm. The calibration graph is rectilinear from 0.01 to 100 µg mL-1. The coefficient of variation is 2.0% at 0.1 µg mL-1 (n = 10). There is no interference by equal amounts of Pt, up to 17.5-fold amounts of Cu or up to 50-fold amounts of many metals, Se or Ge. The limit of detection is 0.7 ng mL-1. The method is applied to alloys and biological reference material.
Arsenic Spectrophotometry Sample preparation Extraction Phase separator Interferences Reference material

"Continuous Hydride-generation System For The Determination Of Trace Amounts Of Bismuth In Metallurgical Materials By Atomic Absorption Spectrometry Using An Online Stripping-type Generator/gas-liquid Separator"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 6 Pages 637-642

Abstract: Sample-solution (1 M HCl medium) preparation procedures are presented for Sn alloys, steel, bronze and brass. A diagram of the flow injection manifold is presented; the sample solution and 1% NaBH4 solution (both 50 µL) are injected simultaneously into streams (both 1.9 ml/min) of water and 1 M HCl, respectively, which subsequently merge (cf. Bergamin et al., Anal. Chim. Acta, 1978, 101, 17) before passage through a 15 cm reaction coil a nd then through a stripping-type gas-liquid reactor-separator (made of acrylic; diagram presented). The generated BiH3 is carried in a stream of N2 to a quartz atomization furnace maintained at 900°C for absorbance measurement at 223.1 nm. The calibration graph is linear up to 100 ng/ml of Bi, and the detection limit is 320 pg/ml. The RSD (n = 20) at 100 ng/ml was 1.9%, and the results for standard reference materials and other alloy samples agreed with the certified values and results obtained by ETAAS, respectively.
Bismuth Sample preparation Spectrophotometry Phase separator Method comparison Reference material Volatile generation Volatile generation

"Determination Of Palladium By Flow Injection Spectrophotometry In An Organic Solvent System Miscible With Water"
Fenxi Shiyanshi 1994 Volume 13, Issue 2 Pages 9-11
Dong, S.A.

Abstract: Sample (50 µL) in 3.6 M HCl solution was injected into the flow injection analyzer. and transferred by a carrier stream of aqueous 80% ethanol to the reaction coil (1.05 m x 0.8 mm i.d.) to mix with a reagent stream containing 0.05% dithio-oxamide in aqueous 80% ethanol (all streams at flow-rate of 2.8 ml/min) before detection at 420 nm. Determination range was 2-12 µg/ml of Pd. Sampling frequency was 240 samples/h. Interfering ions such as V(III), Fe(III), Ir(IV), Au(III) and Cu(II) could be masked. For 8 µg/ml of Pd, the recovery was 98-102% with RSD of 2.1%. The method was applied to the analysis of various catalysts, alloys and aqua-regia insoluble residues. The results compared well with those obtained by spectrophotometry and gravimetry.
Palladium Spectrophotometry Method comparison Interferences