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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Simulation

Classification: Theory -> Simulation

Citations 19

"Modelling Dynamics Of Amperometric Biosensors In Batch And Flow Injection Analysis"
J. Math. Chem. 2002 Volume 32, Issue 2 Pages 225-237
R. Baronas, F. Ivanauskas, J. Kulys

Abstract: A mathematical model of amperometric biosensors has been developed. The model is based on non-stationary diffusion equations containing a non-linear term related to Michaelis-Menten kinetic of the enzymatic reaction. Using digital simulation, the influence of the substrate concentration as well as maximal enzymatic rate on the biosensor response was investigated. The digital simulation was carried out using the finite difference technique. The model describes the biosensor action in batch and flow injection regimes.

"Application Of Artificial Neural Networks Coupled With An Orthogonal Design And Optimization Algorithms To Multifactor Optimization Of A New FIA System For The Determination Of Uranium(VI) In Ore Samples"
Analyst 2000 Volume 125, Issue 5 Pages 921-925
Sun Gang, Zhou Yongyao, Wang Huaiwen, Chen Hongli, Chen Xingguo and Hu Zhide

Abstract: A sensitive and selective spectrophotometric flow injection method has been developed for the determination of uranium(VI) in ore samples, based on the reaction of uranium(VI) with p-acetylchlorophosphonazo (CPA-pA) in a HNO3 medium. Most of the interfering ions were effectively eliminated by the masking reagent, diethyleneaminepentaacetic acid (DTPA). Artificial neural networks coupled with an orthogonal design and penalty algorithm were applied to the modeling of the proposed flow injection system and optimization of the experimental conditions. An orthogonal design was utilized to design the experimental protocol, in which three variables were varied simultaneously. ANNs with a faster back propagation (BP) algorithm were used to model the system. Optimum experimental conditions were generated automatically by using jointly ANNs and optimization algorithms in terms of sensitivity and sampling rate. In the U(VI)-CPA-pA system, Beers law was obeyed in the range 1.0-23.0 µg mL-1, the detection limit for uranium(VI) was 0.3 µg mL-1 and the sampling rate was 100 h-1. The method was applied to the determination of uranium(VI) in ore samples with satisfactory results. It was shown that this method had advantages over traditional methods in respect of improvement in the ability of optimization and reduction in analysis time.

"Graph Methodology And Principles Of Linear Nonequilibrium Thermodynamics In The Theory Of Flow Injection Analysis"
J. Anal. Chem. 2002 Volume 57, Issue 5 Pages 388-398
V. V. Kuznetsov

Abstract: It is shown that chemical, configurational, and informational properties of flow injection systems can be interrelated with the use of the methodology of the graph theory. The main equation of the theory is derived using a mathematical expression of the transition paths from the analyte to the detection of a product of the analytical reaction. Examples of specific developments are discussed for redox reactions, ligand exchange reactions, and heterogeneous exchange reactions, with due regard to, the hidden peculiarities of their chemical mechanisms that are essential for flow analysis and also for on-line pre-concentration by coprecipitation. It is also shown that the conditions obtained in a flow system correspond to the basic postulates of linear nonequilibrium thermodynamics, which provides a basis for a new approach to the theory of flow analysis. An example of a complexation reaction was used for discussing the possibility that a linear interrelation exists between flows and forces in a flow system, which corresponds to the Onsager reciprocal rotation.

"Integrated Conductimetric Detection: Mass Distribution In A Dynamic Sample Zone Inside A Flow Injection Manifold"
Anal. Chim. Acta 1999 Volume 379, Issue 1-2 Pages 99-106
Francisco J. Andrade, Fernando A. Iñon, Mabel B. Tudino and Osvaldo E. Troccoli

Abstract: The insights provided by integrated detection (conductimetric) as a novel approach to follow physical dispersion in continuous-flow manifolds are presented. This approach replaces the conventional instantaneous detection and permits to follow the dispersion phenomena, including details of the radial component as the sample plug travels the manifold. Integrated detection permits to look at the radial dispersion in a detailed manner inaccessible to instantaneous detection. The effect of different experimental parameters affecting mass distribution was studied (e.g., flow rate, tube length and diameter, injected sample volume, and reactor type) and their effects on integrated response curves are discussed. A single channel manifold employing aqueous nitric acid as the conducting carrier, and water injected as sample plug, and playing the role of an insulator, provided the physicochemical model for the reported studies.
Conductometry

"Model For Numerical Simulation Of Peaks In A Flow Injection Analysis System"
Rev. Chim. 2000 Volume 51, Issue 11 Pages 885-888
Vaireanu, D.I.

Abstract: The use of statistics and simulation of the flow injection analysis (FIA) is recommended for determination of the essential characteristics of the peaks with any shape or configuration, with provisions for availability of initial experimental data in the system or information about the FIA components (microwave, flux and injection vol, etc.). The dispersion coefficient was determined with reasonable error margins as well as the image of the of the peaks. The experimental data are related to KCl as flux carrier and K4Fe(CN)6 as electrochemically active specimen. (SFS)
Ferrocyanide Spectrophotometry

"A Random Walk Simulation Of Flow Injection Analysis"
Anal. Chim. Acta 1984 Volume 165, Issue 1 Pages 227-236
D. Betteridge, C. Z. Marczewski and A. P. Wade

Abstract: Dispersion and chemical reaction in a single-channel flow-injection system are modelled by a random walk (stochastic, Markovian chain) method using a microcomputer. The effects of various simulated physical variables are investigated. The model provides valuable insight into the mixing process in flow injection analysis.

"Sample Dispersion With Chemical Reaction In A Flow Injection System"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 181-188
H. Wada, S. Hiraoka, A. Yuchi and G. Nakagawa

Abstract: Computer simulations of signals based on a dispersion equation involving diffusion, convection and chemical reaction terms are reported for systems with and without chemical reaction. 2-(2-Thiazolylazo)-4-methyl-5-(sulfomethylamino)benzoic acid (TAMSMB) is used as the reagent because it reacts very quickly with copper(II) and much more slowly with nickel(II). Comparison of experimental signal profiles with the simulated ones enables sample dispersion from the reaction rates to be elucidated. Concentration profiles of the reaction product in a straight, narrow tube were also stimulated; they explain satisfactorily the signal profiles obtained experimentally.

"A Random Walk Simulation Of Flow Injection Systems With Merging Zones"
Anal. Chim. Acta 1987 Volume 194, Issue 1 Pages 49-60
C. D. Crowe and H. W. Levin, D. Betteridge and A. P. Wade

Abstract: A flow-injection system with merging zones is simulated by using a random-walk stochastic (Markovian chain) model. Variables studied include reagent plug size and offset, reagent concentration and flow rate, injection delay time, reaction stoichiometry, rate constant, diffusion constants, viscosity, and temperature. The reaction of Ca(II) with o-cresolphthalein complexone was used to compare simulated and experimental results. In general, there was good agreement among computed and measured results.
Calcium Spectrophotometry

"Influence Of The Main Parameters Of Single-line Flow Injection Systems Without Chemical Reaction On The Output Signal. 1. Dispersion Characteristics Of The Main Sections Of The Flow System"
Anal. Chim. Acta 1988 Volume 208, Issue 1 Pages 117-132
Spas D. Kolev and Ernö Pungor

Abstract: Single-line flow-injection systems with valve, hydrodynamic, syringe or δ-function injection of the analyte are considered. Appropriate equations for calculating the Peclet numbers of their main sections (i.e., the fore-section, the injection section, the reactor, the measurement cell, and the after-section) are described. Two types of reactor with different dispersion characteristics (i.e., straight tube and coiled tube reactors) are considered. The detector is assumed to measure one of three concentrations: (1) the mean concentration in the cross-section of the flow situated in the middle of the measurement cell; (2) the average integral concentration in the whole volume of the measurement cell; or (3) the average integral surface concentration at the inner walls of the measurement cell. Equations for calculating the Laplace transform of the surface and the integral surface concentration, and for the mean and the variance of the corresponding concentration curves are derived. The conclusions made can be used to investigate the influence of the main parameters of single-line flow-injection systems on sample throughput by simulation of the mathematical models.

"Influence Of The Main Parameters Of Single-line Flow Injection Systems Without Chemical Reaction On The Output Signal. 2. Simulation Of The Mathematical Models"
Anal. Chim. Acta 1988 Volume 208, Issue 1 Pages 133-149
Spas D. Kolev and Ernö Pungor

Abstract: Simulations based on the mathematical models outlined in Part 1 are used to study the dependence of peak broadening on design and performance parameters as well as on the diffusion coefficient of the analyte particles (e.g., ions, molecules), the viscosity of the carrier solution and the temperature of the flow. The Peclet numbers of the various sections of the flow system are calculated by the equations discussed in Part 1. The predictions from the simulations agree fairly well with earlier experimental data. On the basis of the results obtained, various possibilities for increasing the sample frequency of single-line flow-injection systems are outlined.

"Evidence Of Axial Diffusion Accompanied By Axial Dispersion With Zone Circulating Flow Injection And Analysis Data"
Anal. Chim. Acta 1995 Volume 309, Issue 1-3 Pages 227-239
Yoshio Narusawa* and Yuichi Miyamae

Abstract: The inter-relationships of axial and radial dispersion with FIA operating parameters are critically examined and discussed. Using a computer-simulation, the relationship between axial dispersion and analyte residence times is clarified, and a model of axial dispersion free from contributing diffusional effects is presented.

"Simultaneous Dermination Of Iron (II) And Iron(III) By Flow Injection Analysis. A Mathematical Simulation Of The Detector Response"
Anal. Chim. Acta 1997 Volume 348, Issue 1-3 Pages 101-112
Milko Novi, Marjana Novi*, Jure Zupan, Nadja Zafran and Boris Pihlar

Abstract: A mathematical model for the description of the detector signal obtained in flow injection asynchronous merging zone technique (FIA-AMZ) is proposed. FIA-AMZ is based on the separate injection of a sample and an appropriate reagent in such a way that both injected solutions are covered only partly. The resulted detector signal consists of two consecutive peaks whose heights are proportional to the concentration of the detectable component present in the sample and another component which becomes detectable after the reagent has been added. The detector signals (the concentration profiles of the analytes) are described by a modified Gauss curve, which proved to be better than a combination of Gauss-Lorentz curves. The conversion of undetectable to detectable form of the analyte is described by a sigmoidal function the slope of which corresponds to the frontal dispersion of the added reagent and to the reaction kinetics. The model is tested on the system for the simultaneous spectrophotometric determination Fe2+ and Fe3+. It is shown that fitting of the experimental curves with a model function enables the optimization of the experimental conditions at applied FIA manifold, and consequently the simultaneous determination of concentrations of Fe2+ and Fe3+ ions in a single measurement.
Iron(2+) Iron(III)

"Improvement Of Accuracy For The Determination Of Transient Signals Using The Kalman Filter. 1. Simulations"
Analyst 1992 Volume 117, Issue 12 Pages 1925-1928
Ian D. Brindle and Shaoguang Zheng

Abstract: Results of computer simulations are presented to show that the Kalman filter is very efficient for removing white noise in transient signals from one-component systems. Even at a signal to noise ratio of 1:1 the simulated response was recovered with negligible error. The method does not involve initial guesses of variance and estimated value and works best when several hundred data points are available for processing. It should improve detection limits in e.g. flow injection systems and batch hydride generators for analysis of hydride-forming elements and Hg.
Spectrophotometry

"Integrated Fluid Handling System For Biomolecular Interaction Analysis"
Anal. Chem. 1991 Volume 63, Issue 20 Pages 2338-2345
Stefan Sjoelander and Csaba Urbaniczky

Abstract: An integrated fluid-handling system for multi-channel biomolecular-interaction analysis is described. Reactions between biomolecules are monitored in real time by using surface plasmon resonance (SPR) detection. A low channel height (50 m) in the flow cell results in ≈3% adsorption efficiency of the analyte on the biospecific active surface. Sensitivity is good when a large part of the total biospecific active surface for SPR probing (≈0.15 mm2) is used. Samples of 1 to 50 µL can be injected. Dead volume in the system is low (≈0.4 l). Experimental results obtained with an anti-theophylline monoclonal antibody as analyte are compared with a theoretical model. With a 50 µL sample of 250 pM analyte, assay time is 10 min and the standard deviation for the repeatability is ≈5%. The detection limit is ≈10 pg.
LC Electrochemical analysis Electrode

"Digital Simulation Via The Hopscotch Algorithm Of A Microelectrode-based Channel Flow-through Amperometric Detector"
J. Electroanal. Chem. 1991 Volume 301, Issue 1-2 Pages 1-13
P. Pastore and F. Magno, I. Lavagnini, C. Amatore

Abstract: The current flowing at a band ultramicroelectrode in a rectangular channel under mass transfer-limited conditions is computed numerically. The procedure is based on the 'hopscotch' algorithm and on an appropriate space transformation, δ = tanh(x/α). The edge effect is found to influence the response depending on the flow rate. The polarization times necessary to reach the steady-state current are also computed under different operating conditions.
Amperometry Electrode Voltammetry

"Simulation And Modeling In Chemical Analysis"
Anal. Proc. 1984 Volume 21, Issue 4 Pages 139-140
D. Betteridge

Abstract: A short review, with 4 references, is presented of computer simulation and modeling in the optimization of an auto-analyzer., in the application of queuing theory to the analysis of sample throughput and in simulation of flow injection analysis.

"Evaluation Of Artificial Neural Networks For Modelling Enzymatic Glucose Determination By Flow Injection Analysis"
Analusis 1992 Volume 20, Issue 3 Pages 127-133
Campmajo C.; Poch M.; Robuste J.; Valero F.; Lafuente J.

Abstract: Artificial neural networks, which are mathematical algorithms from artificial intelligence techniques that try to model the human brain, are described in detail. The application of these networks to the analysis of complex FIA systems is evaluated with use of an enzymatic glucose analyzer. manifold as a case study. The abilities of the networks to predict the effects of flow rates, injection volume and coil lengths on the response of the FIA system are presented. The networks do not require any prior knowledge of the structure of the relationships that exist between important variables; it is sufficient to supply the networks with pertinent information so that they can learn to relate input and output. Results show that the networks are able to simulate FIA peaks but at present the computer time required for the learning process is very long. Although deterministic models have produced some promising results in the description of FIA single channel manifolds, modeling of more complex systems presents further difficulties to be solved. It is therefore interesting to study the application of new modeling techniques to this problem. The object of this paper is to study the use of neural networks in FIA systems modeling. As a case study, an enzymatic glucose analyzer manifold has been chosen. The abilities of neural networks to predict the effects of flow rates, injection volume and coil lengths on the response of the FIA system are presented. The distinctive advantage of neural networks over some other modeling methods is that they do not require any prior knowledge of the structure of the relationships that exist between important variables. All that is needed is to feed the neural network with sufficient pertinent information so that it can learn to relate input and output. The results obtained show that this methodology is able to simulate FIA peaks, but in the present state of knowledge it has drawbacks related to computer time required for the neural network learning process.
Glucose

"A Computational Technique For Simulating The Dynamic Response Of A Flow Injection Analysis System"
Chem. Eng. Sci. 1992 Volume 47, Issue 7 Pages 1591-1600
Steven H. Isaacs and Henrik Soeberg, Lars H. Christensen and John Villadsen

Abstract: A computational technique is presented for obtaining the dynamic response to a gas diffusion module as part of a flow injection analysis (FIA) system. Based on orthogonal collocation, Laplace transformation, and Fourier series, the method provides a relatively quick way to account for dispersive effects occurring via longitudinal convection and lateral diffusion. Simulation examples, including a comparison with a dynamic signal obtained with an actual FIA system, are provided.

"Simulation Of Flow Injection Analysis Peak Without Molecular Diffusion In Laminar Capillary Flow Injection"
J. Flow Injection Anal. 1986 Volume 3, Issue 2 Pages 91-102
Takashi KORENAGA, Hirofumi YOSHIDA, Yo YOKOTA, Satoru KASENO and Teruo TAKAHASHI

Abstract: The transport phenomena of the injected samples in flowing carrier stream are analyzed elementally. The FIA peak in laminar capillary flow is simulated without considering molecular diffusion by computer. The results obtained by simulation are compared with those obtained by microscopic and photometric detection methods in order to attain higher sampling rate and peak height in FIA. It was found that FIA peak should closely be simulated with the finite element method (FEM) in consideration with molecular diffusion coefficients of the samples.