Polar 3 For Windows:

Electrochemical simulation and data analysis

Dr. Weiguang HUANG
120/22-24 Wassell Street, Matraville, Sydney, NSW 2036, Australia

Phone: (61 2) 93113251

mailto:polarography@bigfoot.com
mailto:pshi@mail.usyd.edu.au

http://www.bigfoot.com/~polarography/
http://members.tripod.com/~showing/

Copyright @ 1990-1998, 1998 June 5

Contents

1. Introduction
2. Features and Prices
3. Menu
4. Input
5. Playing Around

5.1 Running Simulation
5.2 Comparing Curves
5.3 Analysing Data
5.4 Extracting Parameters by Curve Fitting
5.5 Stripping Voltammetry

6. Frequently Asked Questions
7. References

Chapter 1
Introduction

It analytically and digitally simulates voltammograms and stripping voltammograms with charge current, resistance and noise on about 20 mechanisms at 8 electrode geometries (planar, spherical, semi-spherical, cylindrical, semi-cylindrical, microdisc, thin film, and rotating electrodes) in over 5 techniques (linear sweep and CV, DC, normal pulse, differential pulse, and square wave voltammetries).

Its data analysis include detecting peak area, current and potential, semi-derivative, semi-integral, derivative, integral, curve fitting, extracting kinetic parameters from experimental data, separating overlapped peaks.

It shows tip when the user put mouse cursor over a label. The progrom can separate overlapped voltammograms into individuals, and extract real peak from voltammogram with noise and baseline. It outputs the theoretical peak values, the peak current and potential, and current-potential data, which can be imported into other program (e.g. Lotus 123). User can copy-and-paste the voltammogram into his document.

It has been successfully applied to fit experimental polarograms (voltammograms) of In(III), Cd(II), Pb(II), Tl(I), Cr(III), Zn(II), and binuclear copper complex in aqueous and non-aqueous media at mercury, solid metal and non-metal electrodes (specifically the dropping mercury, hanging mercury drop, gold, platinum and glassy carbon electrodes) by various electrochemical techniques (differential pulse, square wave, and pseudo-derivative normal pulse polargraphies) [1-5].

It runs on IBM PC under MS-DOS, Windows 3 and Windows 95, available from the author (public version is available free download from my Web page). If you have any question, please read FAQ in document.

 

Chapter 2
Features and Prices

  • Digital simulation

    • Flexible for various mechanisms.

  • Analytical simulation

    • No divergence problem in simulation. No overflow problem in simulation. Fast simulation.

  • Over 5 techniques

    • Linear sweep, CV, DC, normal pulse, differential pulse, square wave voltammetries. Multi-cyclic voltammetry, cyclic differential pulse voltammetry.

  • Theoretical peak

    • You can compare your data with theoretical peak values to see if your experimental conditions reach theoretical limit or not.

  • Preconcentration

    • You can change preconcentration conditions for stripping voltammetry.

  • Pre-equilibration

  • Curve fitting

    • It manually and auto fits the simulated voltammograms into experimental data, and extracts kinetic parameters from experimental data.

  • Separating overlapped peaks

    • It manually and auto separates overlapped peaks into individuals, and extract real peak from voltammogram with noise and baseline. So you can exactly determine peaks.

  • Import and export data

    • You can export simulated data into your favour program (e.g. Lotus 123). You can copy-n-paste the voltammogram into your document.

  • Derivative, integral, semi-derivative, semi-integral

    • Semi-derivative is useful for CV. It can change a shape of reversible CV into symmetric peak so easy to determine peak.

  • 8 electrode geometries

    • planar, spherical, semi-spherical, cylindrical, semi-cylindrical, microdisc, thin film, and rotating electrodes.

  • About 20 chemical mechanisms

  • Noise

  • Charge current

  • Resistance

  • Tip

    • It shows tip for help when you put mouse cursor over a label. 
    ------------------------------------------------------------------------------------------
version                 Public	        Standard       Professional	Full	competitor
price (US$)             $0              $99             $499		$699	>$2500

digital simulation	y		y		y		y	y
analytical simulation	y		y		y		y	n
theoretical peak 	y		y		y		y	n

techniques:
LSV, CV                	y               y               y		y	y
DC			y		y		y		y	n
normal pulse            y               y               y		y	n
differential pulse      y               y               y		y	n
square wave             y               y               y		y	n

preconcentration	y		y		y		y	n
pre-equilibration	y		y		y		y	y

manual fit     	        n               y               y		y	n
auto fit              	n		n               y		y	y
manual separate		n		n		n		y	n	
auto separate		n		n		n		y	n

import data             n               y               y		y	y
export data             n               y               y		y	n

copy-n-paste            y               y               y		y	n
derivative              y               y               y		y	n
integral               	y               y               y		y	n
semi-derivative         y               y               y		y	n
semi-integral           y               y               y		y	n

electrode:
planar                  y               y               y		y	y
(micro)spherical        y               y               y		y	y
(micro)hemispherical	y		y		y		y	y
(micro)cylindrical      y               y               y		y	y
(micro)hemicylindrical	y		y		y		y	y
microdisc		y		y		y		y	n
thin film		y		y		y		y	n
rotating disc		y		y		y		y	n

tip			y		y		y		y	n
chemical mechanisms     y               y               y		y	y
noise                   y               y               y		y	y
charge current          y               y               y		y	y
resistance		y		y		y		y	y
---------------------------------------------------------------------------------------
note: y = yes, n = no.
 price may be changed.

    Chapter 3
    Menu

    File menu

    Save submenu
    Import Data submenu
    Export Data submenu
    Copy To Clipboard
    Print
    Exit

    Input menu

    Technique submenu
    Mechanism submenu
    Experimental submenu

    Run menu

    Simulate submenu
    Manual Fit submenu
    Auto Fit submenu
    Manual Separate submenu
    Auto Separate submenu

    Display menu

    Option submenu
    Plot submneu
    Next submenu

    Analysis menu

    Find Peak submneu
    Find halfwave E submenu
    Semi-derivative submenu
    Semi-integral submenu
    Derivative submenu
    Integral submenu

    Help menu

    Upgrade submenu
    About submenu

    Some menus will be activated only after you click the Simulate submenu or load data because they require data.

     

    Chapter 4
    Input

    4.1 Techniques window:

    1) Linear sweep and cyclic voltammetry
    2) DC voltammetry
    3) Normal pulse voltammetry
    4) Differential pulse voltammetry
    5) Square wave voltammetry

    The shapes of DC and normal pulse polarogram are S-shape. The shapes of differential pulse and square wave voltammograms usually are peak-shape. But there is effect of the DC term on differential pulse voltammogram.

    4.2 Mechanism window:

    1) A + ne = B
    2) A + ne = B, B + ne = C
    3) A + ne = B, B + ne = C, C + ne = D
    4) A + ne = B, C + ne = D
    5) A = B, B + ne = C
    6) A = B, B + ne = C, C = D
    7) A + ne = B, B = C
    8) A+ ne =B, 2B = C
    9) A + ne = B, B = A
    10) A + ne = B, 2B =A
    11) A + ne = B, B = C, C + ne =D
    12) A + ne = B, B = D, C + ne = D
    13) A + ne = B, B = D, C + ne = D, C = A
    14) A + ne = B, B + ne = C, C = D
    15) A + ne = B, B + ne = C, B = D
    16) A + ne = B, B + C = A + D
    17) A = B + pD, B + ne = C

    4.3 Experimental Window

    Instrumental Parameters Section:

    E start: starting potential (V).
    E end:     ending potential (V).
    E step:     step potential (V).
    v:     scan rate (V/s).
    E pulse:     pulse potential (V).
    T:     temperature (     °C).
    t pulse    : pulse time or pulse width for pulse voltammetry (s).
    t drop:     mercury dropping time or pulse length for pulse voltammetry (s).
    Noise:     ratio of noise to maximum signal (%).
    C dl:     double layer capacitor for charge current (F).
    i 0:     current at first point, or offset current (A).

    Electrode Section:

    Planar: planar electrode.
    (Micro)Spherical: spherical electrode or micro spherical electrode.
    (Micro)Hemispherical: hemispherical electrode or micro hemispherical electrode.
    (Micro)Cylindric: cylindrical electrode or micro cylindrical electrode.
    Microdisc: microdisc electrode, radius < 1e-4 cm
    Thin film: thin film electrode
    Rotating disc: rotating disc electrode
    Area: electrode area (cm2).
    Radius:     electrode radius (cm).
    Length:     electrode length for cylindrical electrode or micro cylindrical electrode, or mercury film thickness for stripping voltammetry (cm).

    Scan Section:

    Single: single scan.
    Cycles: cyclic scan, e.g. cyclic voltammetry (CV).
    2 Cycles: 2-cycle scan.

    Preconcentration Section:

    E pre: preconcentration potential (V).
    R stir: stirring rate (rpm). Stirring solution
    t pre: preconcentration time (s).
    t pre const: preconcentration time constant (/s).
    P const: electrode constant. It only related to electrode.

    Species Section:

    D: diffusion coefficient (cm2/s).
    C anal: analytical concentration (M).
    C init: initial concentration for simulation (M).
    C fitted: fitted value of concentration (M).
    C min: mininum concentration for fitting (M).
    C max: maxinum concentration for fitting (M).

    Heterogeneous Reaction Section:

    ks: heterogeneous standard rate constant (cm/s).
    a    : electron transfer coefficient.
    n:     electron number.
    E    °: standard electrode potential (V).

    Homogeneous Reaction Section:

    kf: forward chemical reaction rate constant.
    kb: backward chemical reaction rate constant.
    Kq: chemical equilibrium constant, Kq = kf/kb.

     

    Chapter 5
    Playing Around

    5.1 Running Simulation

    A simplest way to play simulation is just to click the Simulate submenu under the Run menu. It uses the default values to simulate a linear sweep voltammogram.

    Notice that some menu (e.g. the Display menu and the Analysis menu) will be activated only after run simulation or load data because they require data.

    5.1.1 Effect of Electrode Size - Microelectrode

    Simulation technology for microelectrode is the same as for macro electrode, but the electrode size is very small, e.g. electrode radius is 1e-4 cm. A shape of voltammogram will be changed. Note that the planar electrode geometry is not available for microelectrode.

    5.2 Comparing Curves

    After run first simulation, click the Display menu, and click the Option submenu. Select the Overlap choice, then run second simulation.

    5.3 Analysing Data

    Semi-derivative is useful for CV. It can change a shape of CV into symmetric peak if CV is reversible.

    5.4 Extracting Parameters by Curve Fitting

    5.4.1 Fitting to Simulation Curve

    In order to extract kinetic parameters, you can fit a simulation curve to another simulated or experimental curve. You should manual fit before auto fit. The manual fit shows how well your inital guess values work. It can retrieve any of 20 parameters (concentration C, standard electrode potential E°, and the heterogeneous standard rate constant ks) from voltammogram by curve fitting. If it diverged, you should change their initial values, then try again.

    e.g. run simulation with all default values, then change the C value from 1e-3 to 2e-3 in the Species section, click the Auto Fit menu. You will see the fitted value of 0.001 in the C fitted field next to the C text field.

    5.4.2 Fitting to Experimental Curve

    It is similar to fit simulated curve. But you should input your experimental values of E start, E end, E step, etc. into the Experiemental section. Polar requres data are in SI unit and first peak is positive value. If your experimental data are not, please convert your experimental data.

    5.5 Stripping Voltammetry

    Select the Preconcentration in the Experiential Parameters window. Change the preconcentration potential value in the E pre text field, and preconcentration time in the t pre text field. The preconcentration potential value usually is -0.2/n V to specie’s standard electrode potential. The preconcentration time usually is a number of minutes. You should enter your electrode constant into the P cont text field, and your mercury film thickness into the Length field in the Electrode section of the Experimental window if you use a planar mercury film electrode.

    Chanper 6
    Frequently Asked Questions

    Q: Does it run in Windows 3.1 or 3.11 ?
    A: It may run in Windows 3.1 or 3.11 if you had 32bit win32.dll. It also need Microsoft Visual Basic runtime DLL file msvbvm50.dll. Copy msvbvm50.dll into your directory \windows\system, then run polar26a.exe.

    Q: When I installed to run setup.exe in polar26a.zip, an error occured:
    while registering the file
    >c:\windows\system\MSRD2x35.dll
    Shall I (Abort, Retry, Ignore) ?
    A: Ignore. Do not worry about MSRD2x35.dll. Running Polar did not use it, only setup.exe in polar26a.zip check it.

    Q: As I have above problem, I click the Ignore, but it crashes after starting polar26a.exe.
    A: I guess you are running it under non-Engilsh version of Windows. Please try it under English version of Windows. Some non-Engilsh version of Windows have problem to run English version program.

    Q: Still have install problem ?
    A: I suggest you close all programs (include Office, Mail) before install Polar. If you still have problem, try to register file msvbvm50.dll by double click or type following command in DOS:

    Cd \windows\system
    Regsvr32 msvbvm50.dll
    then start polar26a.exe.

    Q: Why are some menus grey ?
    A: Some menus will be activated only after you click the Simulate menu or load data because they need data.

    Q: I cannot see any chemical reaction in Public version. Is this part of the program not finished yet or is it only available in the registered version ?
    A: It is only available in the registered version. The registered versions include common mechanisms. Please read document for details. Mechanisms may be available in next Public version.

    Q: Does it include my mechanism ?
    A: If your mechanism is missing, please send your requirement into author. Author may add your mechanism into new version special for you.

    Q: Can it fit data by curve fitting ?
    A: Yes. As easy as just point and click.

    Q: Can I change graph into other program Lotus 123 or Excel ?
    A: Yes. You export data in text file, then read data into Lotus 123 or Excel.

    Q: Some submenus semi-derivative, semi-integral, derivative, integral, seem to not work sometime. How can I do ?
    A: You should first click the Next submenu under the Plot menu, then try semi-derivative submenu.

    Q: How much does registration cost ?
    A: Less than US$100.

    Q: How can I get registered version ?
    A: You will receive it if you send author register fee by check or money order.

    Q: What are difference among Public, Standard and Professional, and Full version ?
    A: The Public version is free for teaching. The Standard version is for average users, the Professional version is for professionals.

    Q: How does it compare to other competitor ?
    A: See the table in Chapter 2 Features and Prices. You try it before you buy. You do not pay more than $2500 for some program that simulate a single technique CV only. You do not worry about if you lose Dongle. Polar does not need the Dongle to run. Some program are copy-protected, but Polar is not.

     

    Chapter 7
    References

    [1] W. Huang, T. Henderson, A.M. Bond and K.B. Oldham, Curve fitting to resolve overlapping voltammetric peaks: model and examples, Anal. Chim. Acta, 1995, 304, 1-15.

    [2] A. Bond, W. Huang and K. Oldham, Studies of overlapping peaks in pulse polarography: resolution on reversible electrode processes, Proc. of 7th Australian Electrochem. Conf., Uni. of New South Wales, Sydney, Australia, 1988, p 383.

    [3] A. Bond, W. Huang, T. Henderson and K. Oldham, Classification of Methods for Resolving Overlapping Signals, Proc. of Chinese Chemistry Symposium, La Trobe Uni., Melbourne, Australia, 1990, p 8-9.

    [4] W. Huang, B. Hibbert and A. Bond, Evaluation of resolution of polarographic peaks, Proc. of 9th Australian Electrochem. Conf., Uni. of Wollongong, Wollongong, Australia, 1994, p 75.1-75.3.

    [5] W. Huang and B. Hibbert, Computers & Chem., 1995.