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: Geological -> ore -> refined

Citations 3

"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

"Application Of Three Chromogenic Reagents To The Determination Of Palladium Using A Laboratory-made Optical-fibre Detector For Flow Injection Analysis"
Anal. Chim. Acta 1992 Volume 262, Issue 1 Pages 97-102
Yanjun Xu, Xingguo Chen, Mancang Liu and Zhide Hu

Abstract: The design and operation of an optical-fiber detector are presented. Palladium in refined ores was determined with 3-(4-chloro-2-phosphonophenylazo)-6-(6,8-disulfo-2-naphthylazo)chromotropic acid (I), 3-(4-chloro-2-phosphonophenylazo)-6-(4-sulfamoylphenylazo)chromotropic acid (II) or N-~4-[7-(4-chloro-2-phosphonophenylazo)-1,8-dihydroxy-3,6-disulfo-2-naphthylazo]benzoyl~glycine (III) as chromogenic reagent. All measurements were made at 90°C and in acidic (H2SO4) medium. The system was optimized in respect of concentration. of the chromogenic reagent, acidity and temperature Results were obtained from calibration graphs, which obeyed Beer's law in the ranges 1 to 3, 1 to 4 and 1 to 5 µg mL-1 for I, II and III, respectively; the corresponding ε values were 4.3 x 10^4 (650 nm), 3.0 x 10^4 (640 nm) and 3.4 x 10^4 (630 nm). In each instance the limit of detection was 0.5 µg mL-1. Recoveries were >90% and there was no interference from co-existing noble-metal ions. Results were compared with those obtained with a spectrophotometric detector. Palladium in ores was determined by a method in which an optical fiber detector is connected to a flow injection analysis system and using three chromogenic reagents, i.e., 1,8-dihydroxy-2-(4-chloro-2-phosphonophenylazo)-7-(6,8- disulfonaphthylazo)naphthalene (I), 1,8-dihydroxy-2-(4-chloro-2- phosphonophenylazo)-7-(4-sulfonamidophenylazo)-3,6- disulfonaphthalene (II) and 1,8-dihydroxy-2-(4-chloro-2- phosphonophenylazo)-7-(p-hippuric acid azo)-3,6-disulfonaphthalene (III). The methods are simple, rapid and selective. In the Pd-I system, the molar absorptivity is 4.3 x 10^4 L mol-1 cm-1 at 650 nm and Beer's law is obeyed in the range 1-3 µg Pd mL-1. In the Pd-II system, the molar absorptivity is 3.0 x 10^4 L mol-1 cm-1 at 640 nm and Beer's law is obeyed in the range 1-4 µg Pd mL-1. In the Pd-III system, the molar absorptivity is 3.4 x 10^4 L mol-1 cm-1 at 630 nm and Beer's law is obeyed in the range 1-5 µg Pd mL-1. Coexisting noble metal ions do not interfere. An optical fiber detection cell for flow injection analysis and an optical fiber-spectrophotometer were designed and constructed in house.
Palladium Spectrophotometry Optical fiber Apparatus Detector Interferences Chromogenic reagent

"Determination Of Osmium(VIII) By Flow Injection Kinetic Methods Using Bromopyrogallol Red And Hydrogen Peroxide"
Microchem. J. 1995 Volume 52, Issue 3 Pages 364-369
Chen X. G., Gong H. P., Zhang Q. and Hu Z.

Abstract: The method was applied to refined ores and chlorination residues. Sample (1 g) was mixed with 3 g Na2CO3 and 1 g MgO, heated at 550°C for 15 min, then fused with 7 g Na2O2 at 700°C for 30 min. The melt was treated with 9 M H2SO4, 30% H2O2 and water and the Os was distilled as OsO4 into dilute NaOH. The distillate was treated with H2SO4, diluted with water and portions (100 µL) were injected into a carrier stream (0.6 ml/min) of sodium acetate/acetic acid buffer of pH 5.7. After reaction with streams (0.6 ml/min) of 0.6 mM bromopyrogallol red and 1.2% H2O2 using a 12 cm mixing coil and 100 cm reaction coil (80°C) of 0.5 mm i.d., the decrease in absorbance was measured at 559 nm. The calibration graph was linear for 4-100 ng/ml Os(VIII) and the detection limit was 3 ng/ml. The RSD were 1.8% and 0.76% for ore and chlorination residues, respectively, and the corresponding recoveries were 97.5-101.3% and 96-101.3%. The sample throughput was 47/h. Interference from Ru(III), Rh(III), Ir(IV), Mn(II) and Cr(III) was eliminated by the distillation step.
Osmium(VIII) Spectrophotometry Heated reaction Interferences Kinetic