Polar For Windows: Electrochemical simulation
Polar 3.2 For Windows:
Electrochemical simulation and data analysis
W.S. Ping Company
124 Eastern Avenue, Kingsford, Sydney, NSW 2032, Australia
Phone: (61 2) 9662 0516
mailto:polarography@bigfoot.com
mailto:showing@fcmail.com
http://www.bigfoot.com/~polarography/
http://www.bigfoot.com/~showing/
Copyright @ 1990-1999
1999 Feb. 1
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), and outputs current, resitance,
conductivity and surface concentration.
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].
Its 32-bit version Polar32 runs on IBM PC under Windows 3.11/95/98/NT
while its 16-bit version Polar32b runs under Windows 3/3.1/3.11/95/98/NT.
They are available from the author or download from my Web site.
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.
- 4 Outputs
It outputs current, resitance, conductivity and surface concentration. I vs. E, R vs. E,
Cond vs., C vs. E
- 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. MS Excel). 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.
Table 2 Features
-------------------------------------------------------------------------------------
version Public Standard Professional Full competitor
price (US$) $1 $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
cyclic DPV y y y y n
square wave y y y y n
Output:
outputs current y y y y y
resitance y y y y n
conductivity y y y y n
surface concentration y y y y y
preconcentration y y y y n
pre-equilibration y y y y y
manual fit n y y y y
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 y
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 y
rotating disc y y y y y
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
electrolyte y y y y n
-------------------------------------------------------------------------------
note: y = yes, n = no.
price may be changed.
Chapter 3
Menu
File menu
- Save submenu
It saves experimental parameters.
- Import Data submenu
It imports data file into Polar.
- Export Data submenu
It export data to other program as data file. e.g. if you export data as the .csv
file, you open it into MS Excel by double-clicking it.
- Copy To Clipboard
It copy graph into clipboard, so you can paste graph into your document.
- Print
It prints graph.
- Exit
Input menu
- Technique submenu
- Mechanism submenu
- Experimental submenu
Run menu
- Simulate submenu
It runs simulation.
- Manual Fit submenu
It fit simulated curve into experimental curve as you manually change parameter value.
- Auto Fit submenu
It auto fit simulated curve into experiemental curve.
- Manual Separate submenu
It auto separate overlapped peaks into indiviuals as you manually change parameter value.
- Auto Separate submenu
It auto separate overlapped peaks into indiviuals.
Display menu
- Option submenu
It is to change plot options.
- Plot submneu
It plots curve without run simulation.
- Next submenu
It plots next curve.
Analysis menu
- Find Peak submneu
- Find halfwave E submenu
- Semi-derivative submenu
- Semi-integral submenu
- Derivative submenu
- Integral submenu
Help menu
- Logon submenu
You logon to activate menus by input of password.
- About submenu
It displays info about author.
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). For square wave voltammetry, v=E step/t pulse.
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).
R:resistance (Ohm).
Scan:
Single: single scan.
Cycles: cyclic scan, e.g. cyclic voltammetry (CV).
2 Cycles: 2-cycle scan.
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).
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: On which platforms can I run Polar?
A: Its 32-bit version Polar32 runs on IBM PC under Windows 3.11/95/98/NT
while its 16-bit version Polar32b runs under Windows 3/3.1/3.11/95/98/NT.
The 32-bit version needs Microsoft Visual Basic 6 runtime DLL file msvbvm60.dll in the same
directory as Polar or in the directory \windows\system for Windows 3.11 or 95, or in the
directory \winnt\system32 for Windows NT.
The 16-bit version needs Microsoft Visual Basic 4 runtime DLL files vb40016.dll and oc25.dll in the same
directory as Polar or in the directory \windows\system for Windows 3.1, or in the
directory \winnt\system for Windows NT.
Q: When I installed to run setup.exe, 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,
setup.exe check it only.
Q: As I have above problem, I click the Ignore,
but it crashes after starting Polar.
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 msvbvm60.dll
then start Polar.
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 versions ?
A: The Public version is for teaching, the Standard version is for average users, the
Professional version is for professionals, and the Full version is for special users.
Q: When I run the SWV with default conditions as
a digital simulation, it does not appear to give the correct curve. Why ?
Because default conditions are for linear sweep and CV only. For SWV, DC,
NPV and DPV, you should change scan rate v to 0.01. For SWV you should calculate correct
scan rate by v=E step/t pulse before run digital simulation.
Q: How does it compare to other competitor ?
A: Polar has more features and is cheaper, see details on 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] W. Huang and B. Hibbert, Computers & Chem., 1995, 19(4), 433.
[3] W. Huang and B. Hibbert, Computers & Chem., 1995, 19(4), 435.
[4] W. Huang and B. Hibbert, Polar 2.0 for Windows: simulator of voltammogram, Chem. in
Aus., 1996, 131.
[5] J. Mo, P. Cai, W. Huang and F. Yun, Theory and application on multiple
semidifferential electrochemical stripping analysis with thin mercury film formed in situ,
Acta Chimica Sinica, 1984, 42(6), 556-561, CA 101: 162712.
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