University of North Florida
Browse the Citations

Contact Info

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

View Stuart Chalk's profile on LinkedIn


Classification: Industrial -> catalyst

Citations 8

"Determination Of Pd(II) By Application Of An On-line Microwave Oven And Artificial Neural Networks In Flow Injection Analysis"
Anal. Chim. Acta 2000 Volume 420, Issue 1 Pages 123-131
Sun Gang, Chen Xingguo, Zhao Yunkun, Liu Mancang and Hu Zhide

Abstract: A new methodology based on the coupling of an on-line microwave oven, employed to accelerate low-rate reactions, and artificial neural networks (ANNs), applied to the modeling and optimization of a new flow injection system, is proposed. In comparison with traditional heating, a microwave can accelerate low-rate reactions more remarkably and consume less energy. ANNs with a faster back-propagation (BP) algorithm are applied to model the system. Optimum experimental conditions are generated automatically by using jointly ANNs and optimization algorithms in terms of sensitivity, sampling rate and the energy consumed by a microwave oven. The methodology is tested on a new flow injection system for the spectrophotometric determination of Pd(II) with chlorophosphonazo-p-Cl (CPA-pC) in H2SO4 media, which has first been used as chromogenic reagent in the quantitative analysis of palladium. It is shown that the methodology can improve the ability of optimization, reduce analytical time, enhance sensitivity and consume less energy in comparison with traditional methods.
Palladium(II) Spectrophotometry Neural network Optimization Microwave Heated reaction Interferences Reference material

"Selective Stopped-flow Injection Spectrophotometric Determination Of Palladium(II) In Hydrogenation And Automobile Exhaust Gas Converter Catalysts"
Anal. Chim. Acta 2000 Volume 412, Issue 1-2 Pages 161-167
Aristidis N. Anthemidis, Demetrius G. Themelis and John A. Stratis

Abstract: A stopped-flow injection spectrophotometric method is reported for the determination of palladium(II), using 2,2-dipyridy-2-pyridylhydrazone (DPPH) as a color forming reagent. The absorbance of the Pd(II)-DPPH complex was monitored at 540 nm, at pH approximate to 0.3. The various chemical and physical parameters were optimized and a study of interfering ions was also carried out. The calibration graph has two linear parts, first in the range 0-25 mg L-1 (s(r)=0.44%, r=0.9999) with a detection limit of c(L)=0.084 mg L-1 and the second in the range 25-60 mg L-1 (s(r)=1.6%, r=0.9996). In both cases the sampling rate was 30 injections per hour. The method is very selective because the strongly acidic medium used prevented the formation of complexes of the reagent with other ions. The method was successfully applied to the determination of palladium in hydrogenation and automobile exhaust gas converters catalysts. The relative standard deviation of the mean values and the recovery ranged between 0.6 and 1.6% and 97.0-102.6%, respectively.
Palladium(II) Spectrophotometry Stopped-flow Optimization Interferences

"Flow Injection Spectrophotometric Determination Of Palladium In Catalysts And Dental Alloys With 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)aniline"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 271-277
Tadao Sakai and Norko Ohno

Abstract: Sample solution (100 µL, containing 10 µg L-1 of Pd) was injected into the carrier stream (0.1 M HCl; 0.85 mL min-1) which was then mixed with 0.15 mM 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)aniline in acetate buffer (pH 3.7; 0.85 mL min-1) in a 2-m reaction coil. The absorbance was measured at 612 nm (e = 98,400). The calibration graph was rectilinear for 10 to 100 µg L-1 of Pd and the detection limit was 2 µg l-1. The coefficient of variation (n = 10) for 100 µg L-1 of Pd was 0.6%. The sample throughput was 50 h-1. Interference from Cu could be masked by adding 1 mM EDTA solution to the carrier stream. The method was applied in the determination of Pd in catalysts and dental alloys and results agreed well with those obtained by ICP-AES.
Palladium Spectrophotometry Interferences Method comparison

"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

"Study On A Chemiluminescence System Of Luminol - Sodium Perchlorate - Potassium Iodide - Hydroxide Ions For Determination Of Platinum"
Huaxue Shiji 1991 Volume 13, Issue 1 Pages 50-52
Li Qingyi,and Liu Yingjin

Abstract: Platinum was determined by flow injection chemiluminescence with use of a reagent solution (comprising 8 mL of 1 M luminol solution in 0.1 M KOH, 20 mL of 1 mM KOH and water to 100 ml) and a test solution (containing 5 mL of KH phthalate - KOH buffer solution of pH 5.5, 2.5 mL of 0.2 M NaClO4, 1 mL of 50 mM KI, Pt(IV) solution and water to 25 ml). Under optimum conditions, the calibration graph was rectilinear from 0.04 to 2.4 and from 0.8 to 8.0 µg of Pt. The detection limit was 27 ng and the coefficient of variation (n = 9) was 1.9%. The effects of 28 common ions on the determination of Pt were investigated. The method was used to determine trace Pt(IV) in catalysts; recoveries were 99.2 to 100.6%.
Platinum Chemiluminescence Buffer Catalysis pH

"Resolution Of Binary Mixtures Of Metal Ions By Flow Injection Analysis"
J. Flow Injection Anal. 1993 Volume 10, Issue 1 Pages 56-65
F. Sanchez Rojas, E. Cristofol Alcaraz and J. M. Cano Pavon

Abstract: Sample (260 µL) containing Co, Ni or Cd ions was injected into a stream of water (1.6 ml/min) and carried to a reaction coil (116 cm x 0.5 mm i.d.) where it was mixed a stream of 0.1% 4-phenylthiosemicarbazone in DMF (0.7 ml/min). After passing through a second reaction coil (150 cm x 0.5 mm i.d.) where mixing with streams (1.1 ml/min) of either 3 M HClO4 or acetate buffer of pH 5.2 occurred, the absorbance was measured at 430 and 440 nm. A diagram of the system is given. The calibration graphs were linear from 0.4-30 µg/ml of Co and Ni ions (using HClO4 and buffer, respectively) and from 0.5-50 µg/ml of Cd ions (using buffer); corresponding RSD (at 5 µg/ml) were 0.39-0.68%, 1% and 2.5-4.9%. Ni and Cd were successfully determined in Co/Ni mixtures from 1:1-30:1 and in Co/Cd mixtures from 8:1-1:7, by subtracting the absorbance measured using HClO4 (due to Co) from that measured using buffer (due to Co, Ni and Cd). Interferences from foreign ions are tabulated. The method was applied to the determination of Co and Ni in catalysts.
Metals Cobalt Nickel Spectrophotometry Interferences Buffer Dual detection Simultaneous analysis

"Analyses Of Some Practical Samples By FI-MPT-AES"
Jilin Daxue Ziran Kexue Xuebao 1998 Volume 36, Issue 1 Pages 91-93
Zou Mingqiang; Wang Daning; Zhao Xiaojun; Liang Feng; Yuan Mao; Zhang Hanqi; Jin Qinhan

Abstract: The analyzes of some practical samples by FI-MPT-AES (flow injection-microwave plasma torch-at. emission spectrometry) were carried out for samples including Al alloy, alloy steel, catalyst, and biological samples. The method established is acceptable for analyzing the practical samples.

"Graphite Furnace Atomic Absorption Spectrometric Determination Of Rhodium After Online Ion-Exchange Preconcentration"
Anal. Lett. 2004 Volume 37, Issue 13 Pages 2685-2700
Fuensanta Sánchez Rojas, Catalina Bosch Ojeda, José M. Cano Pavón

Abstract: A method for the determination of rhodium in different samples at trace levels is presented. The investigated metal is pre-concentrated on a chelating resin microcolumn [1,5-Bis(2-pyridyl)-3-sulphophenyl methylene thiocarbonohydarzide (PSTH) immobilized on an anion-exchange resin (Dowex 1x 8-200)] placed in the autosampler arm. The modification of the autosampler in the tubing line and circuit allowed either the flow of the sample through the column or the operation of the autosampler in the normal mode, where microlitres of 4 M HNO 3, which acts as the elution agent, pass through the microcolumn eluting Rh(III), which is directly deposited in the graphite tube as a drop of a precisely defined volume. The detection limit is 0.3 ng mL -;1. Linearity is maintained in the concentration range 0-50 ng mL -;1 for rhodium, with correlation factor of 0.999 and relative standard deviation of 1.8% for 10 ng mL -;1 of Rh. The effects of various parameters such as pH, concentration and volume of eluent, sample loading time, sample flow rate, and interference of a large number of metal ions and anions on the determination of this metal was studied in detail to optimize the conditions for their determination in various samples. The method is found to be highly selective, fairly sensitive, simple, rapid and economical, and may be safely applied to their determination in different complex materials, such as environmental samples and catalysts.
Rhodium Spectrophotometry Preconcentration Column Dowex Optimization Interferences