Related Manuals for eDAQ Potentiostat
Summary of Contents for eDAQ Potentiostat
- Page 1 Potentiostats, User Manual Potentiostat, Picostat & QuadStat Overload Overload Potentiostat Picostat Channel 1 Channel 2 Channel 3 Channel 4 QuadStat ® e-corder eDAQ www. .com...
- Page 2 QuadStat are trademarks of eDAQ Pty Ltd. Chart email: info@eDAQ.com and Scope are trademarks of ADInstruments Pty Ltd and are used under license by eDAQ. EChem is a All rights reserved. No part of this document may be trademark of eDAQ Pty Ltd.
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Page 3: Table Of Contents
The Overload Indicators 43 C Connectors 10 The Back Panel 45 Grounding Connector 10 E Out, I Out and E In Connectors 45 Connecting the Potentiostat 11 C Connectors 46 First Use 13 Grounding Connector 46 Potentiostat Control Window 14... - Page 4 5 Techniques A Technical Aspects Introduction 62 Potentiostat 89 Linear Scan Techniques 63 Picostat 91 Fast Cyclic Voltammetry 63 QuadStat 92 Chronoamperometry with Chart 65 On Windows computers 66 B Troubleshooting On Macintosh 68 Analysis of Chronoamperometry 70 Chronoamperometry with Scope 74...
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Page 5: Overview
• QuadStat (EA164), Chapter 4. Four channel, three electrode potentiostat with gain ranges of 2 nA to 1 mA with current signal offset. They are a part of the family of fully–software controlled modular preamplifiers (eDAQ Amps) which are designed for use with the e-corder ®... -
Page 6: How To Use This Manual
How to Use this Manual This manual describes how to set up and begin using your Potentiostat (Chapter 2), Picostat (Chapter 3), or QuadStat (Chapter 4). Their use with Chart and Scope software is also described (Chapter The appendices provide technical and troubleshooting information. -
Page 7: Checking The Unit
Checking the unit Before you begin working with the Potentiostat, Picostat, or QuadStat please check that: • all items described in the packing list are included; and that • there are no signs of damage that may have occurred during transit. - Page 8 Potentiostats...
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Page 9: The Potentiostat
IMPORTANT: Always make sure that the e-corder is turned off before you connect or disconnect the Potentiostat. Failure to do this may result in damage to the e-corder and/or the Potentiostat. NEW FEATURES: If you have used the older EA160 Potentiostat before, then you will notice that the EA161 has new front and back panels, and incorporates several new features: iR compensation;... -
Page 10: The Front Panel
Figure 2–1. The Electrode Connector The electrode connector of the Potentiostat provides connection pins for the Working, Auxiliary and Reference electrode lead wires. The connector also provides connections for the lead shields which protect the signals in the cable wiring from electrical interference (noise pickup). -
Page 11: Electrode Cable
Electrode Cable The Potentiostat is supplied with an electrode cable comprising three To ensure good grip, the leads, with each lead terminated by an alligator clip. The Reference electrode cable alligator... -
Page 12: The Online Indicator
2–1. When lit, it indicates that the software (such as EChem, Chart or Scope) has located and initialised the Potentiostat. If the light does not go on when the software is run, check that the Potentiostat is properly connected. If there is still a problem, please refer to... -
Page 13: The Back Panel
The Potentiostat back panel has three BNC connectors labelled E Out, I Out, and E In. The E In is connected to the Output of the e-corder , usually Output + is used.Reverse the polarity of the Potentiostat by using e-corder Output –. -
Page 14: C Connectors
‘ground loop’ and increased signal interference! You can try grounding the Faraday cage via its own connection to earth, or via the Potentiostat ground cable — but not by both methods simultaneously. -
Page 15: Connecting The Potentiostat
I C Input connector on the back panel of the Potentiostat. Use the three BNC cables to connect the back panel of the Potentiostat to the front panel of the e-corder as shown in Table 2–2. - Page 16 Check that all connectors are firmly attached. Loose connectors can cause erratic behaviour, or may cause the Potentiostat to fail to work. eDAQ Potentiostats...
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Page 17: First Use
Input Channel 1 and the potential signal to e-corder Input Channel 2. (It is possible when using Chart or Scope software to connect the Potentiostat to other e-corder input channels, in which case the description that follows would change accordingly). -
Page 18: Potentiostat Control Window
To connect to the Potentiostat lead wires you must select Real mode. When you click Cancel or OK the Potentiostat will revert to Standby mode until recording is started. Now select Dummy mode operation. You will need to adjust the gain range to 20 µA to accommodate your signal amplitude. - Page 19 With Scope software, the corresponding controls are shown in Figure 2–9. Modes of Operation The EA161 Potentiostat can be operated in several different modes by selecting the appropriate radio button: • Potentiostat (Chart, Scope or EChem software), described below. For three–electrode use connect the working (green), reference and...
- Page 20 ‘counter electrode’. • Galvanostat (Chart and Scope software), page 77 – 82. Connect the electrodes as described for potentiostat operation, above. Note especially that the potential signal is provided at I Out, Figure 2–3.
- Page 21 Setting the Range Use the Range pop-up menu to select the input current range (channel sensitivity). The Potentiostat has ranges of 100 mA to 2 nA, while resolution within each range is 16 bits or 0.0015%. You should set the range so that it is larger than the biggest current that you expect to encounter during your experiment.
- Page 22 — it does not reverse the direction of actual current flow at the electrodes! Cell Control The Potentiostat can be in one of three cell modes, controlled by the Cell radio buttons: • Standby: If Standby mode is selected the electrode lead wires are disconnected, and the internal dummy cell is connected.
- Page 23 (for example where large surface area electrodes are being used in highly resistive solutions). Do NOT use High Stability, when in Potentiostat mode, unless you first encounter stability problems. High Stability decreases the bandwidth of the of the Potentiostat control loop.
- Page 24 When in Potentiostat mode clicking the Calibrate button will zero the current signal, using the Dummy cell, including any signal due to any small offset from the e-corder Output at E In. Thus it should be considered a ‘relative zero’.
- Page 25 To avoid this happening it is usual to always slightly undercompensate, that is, to find the point of ideal compensation and then to reduce the setting slightly.
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Page 26: Maintenance
1 µA with 2 V, etcetera. Try several different potentials and make sure an appropriate current signal is observed in each case. If this test produces the expected results then your Potentiostat is likely to be functioning correctly. Next use the Potentiostat in Real Cell mode to... - Page 27 (reference electrodes, in particular, tend to become clogged or dry out with age), and the design and condition of the reaction vessel, and any salt bridges that you are using. Chapter 2 — The Potentiostat...
- Page 28 Potentiostats...
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Page 29: The Picostat
You can do this (after first connecting the Picostat and e-corder) by touching the outer casing of the e-corder or Picostat. This will connect you to earth (via the electrical grounding of the instrument) and any static charge you have collected will be dissipated. eDAQ Potentiostats... -
Page 30: The Front Panel
Overload indicator light Picostat Online indicator light Alignment dot Auxiliary Electrode Working Electrode Figure 3–2 The Picostat Electrode connector as seen when looking at the front Working Electrode Shield Not connected panel. Reference Electrode Reference Electrode Shield eDAQ Potentiostats... -
Page 31: Electrode Cable
Color Electrode Table 3–1 Yellow Reference Color-coding on the leads of the electrode Green Working cable. Auxiliary Electrode Cable The Picostat is supplied with a three lead electrode cable, with each lead terminated by an alligator clip. The Reference and Working electrode leads are shielded to protect the signals from external interference. -
Page 32: The Overload Indicator
NOTE: A potential overload is quite different from a current overload condition. A current overload is caused when the current signal exceeds the full scale limits of the sensitivity setting of the current channel. This is, in turn, due to a low resistance between the electrodes. eDAQ Potentiostats... -
Page 33: The Back Panel
BNC output BNC input connectors connector Figure 3–3 The Picostat back panel. E Out I Out E In 4 mm socket, ground connection Input Output DB-9 pin, I C connectors The Back Panel The back panel of the Picostat is shown in Figure 3–3. -
Page 34: Grounding Connector
A cable is provided with the Picostat for this purpose. The pin assignments are shown in Figure 3–4. The Output connector can be used for the attachment of other eDAQ Amps. More information about the I C connector can be found in your e-corder Manual. -
Page 35: Connecting The Picostat
via the three pin mains power connector. It is of course important that the power socket that you are using is well earthed. The purpose of this ground cable to the Faraday cage is to provide an easy means of grounding the cage — please note that it is not for grounding the Picostat. - Page 36 Check that all connectors are firmly attached. Loose connectors can cause erratic behaviour, or may cause the Picostat to fail to work. eDAQ Potentiostats...
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Page 37: First Use
Input Amplifier dialog box, described in the Chart and Scope Software Manuals which are installed as pdf files in the eDAQ Documentation folder on your computer hard disk. First Use After you have installed the software, connected the e-corder and... - Page 38 Select input labels to adjust axis range Select low- pass filter Select Real or Standby mode Current signal display area Enter Applied Potential Slider bar for setting applied potential Axis expansion/ Set mains filter Invert signal Pause/Resume contraction scrolling eDAQ Potentiostats...
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Page 39: Picostat Control Window
not recognised the Picostat. Exit the software, check all your connections and try again). By default, the control window opens with the Picostat in Standby mode, that is with the reference and working electrodes isolated so that no current will flow through your electrodes. To connect to the Picostat lead wires you must select Real mode. - Page 40 The Picostat has ranges of 10 pA to 100 nA (if you require a system to monitor larger currents, the Potentiostat has ranges of 20 nA to 100 mA). You should set the range so that it is larger than the biggest current that you expect to encounter during your experiment.
- Page 41 Filtering The Picostat has an internal 10 Hz low-pass filter for removal of high frequency signals (‘noise’). The Off setting gives the full bandwidth of the Picostat which can be up to 16 kHz (but which may also be limited by the characteristics of your electrodes and sample solution).
- Page 42 When using Chart software on a Windows computer you can select the checkbox labelled ‘Set applied potential as baseline…’ This causes the potential set with the slider bar or text entry to be transferred to the Stimulator baseline control when the window is closed. eDAQ Potentiostats...
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Page 43: Maintenance
If the current signal is drifting significantly, or is greater than ±5 pA, then contact your eDAQ representative — it is possible that stray static discharge may have damaged the Picostat’s electrometer chip. - Page 44 Potentiostats...
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Page 45: The Quadstat
You can do this (after first connecting the QuadStat and e-corder) by touching the outer casing of the e-corder or QuadStat. This will connect you to earth (via the electrical grounding of the instrument) and any static charge you have collected will be dissipated. eDAQ Potentiostats... -
Page 46: The Front Panel
WE leads are shielded to protect the signals from external interference. The shields are driven to the same potential as the electrode to minimize lead capacitance. If two-electrode operation is required the auxiliary and reference electrode leads (red and yellow) can be attached to the single ‘counter electrode’. eDAQ Potentiostats... -
Page 47: The Online Indicators
Color Electrode Table 4–1 Yellow Reference Color-coding on the leads of the electrode Green Working cables. Auxiliary The Online Indicators Along the lower edge of the QuadStat front panel are a series Online indicators, Figure 4–1. When lit, they indicate that the software (such as EChem, Chart or Scope) has located and initialised that QuadStat channel. - Page 48 4 mm socket, ground connection Figure 4–2 The QuadStat back panel. Made in Australia by eDAQ Pty Ltd. No user serviceable parts inside. Refer servicing to qualified service personnel. Channel 4 Channel 3 Channel 2 Channel 1...
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Page 49: The Back Panel
Figure 4–4 The I C connectors. ▲ WARNING! The I C connectors are for the power and control of eDAQ Amps, page 2, and should not be used for connection to any other device. Input Output Chapter 4 — The QuadStat... -
Page 50: C Connectors
QuadStat for this purpose. The pin assignments are shown in Figure 4–4. The Output connector can be used for the attachment of another QuadStat, or other eDAQ Amp. More information about the I C connector can be found in your e-corder Manual. Grounding Connector... - Page 51 provide a second pathway to earth which could result in a ‘ground loop’ which can actually increase signal interference! The grounding connector is equivalent to the COM pins of the 20 pin terminal socket, Figure 4–2. Channel 4 Channel 4 Channel 3 Channel 3 Channel 2...
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Page 52: Connecting The Quadstat
* It is not always necessary to monitor E Out depending on your experimental requirements. † Connections to E In are only required if using an external waveform to control the applied potential. ‡ Use Output + to send a signal of reverse polarity to the QuadStat. eDAQ Potentiostats... - Page 53 Channel 1 Channel 2 Channel 3 Channel 4 QuadStat QuadStat Figure 4–7 The QuadStat shown connected to an e-corder, front view, Input 1 Input 2 Input 3 Input 4 Input 5 Input 6 using the connections described in Table 4–2. Power Trigger Output...
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Page 54: Using A Common Reference And Auxiliary
WE electrode. The auxiliary and reference leads of channel 2 are joined together. Channel 1 auxiliary, Channel 2 auxiliary and reference and working leads reference leads connected to be connected to AE, RE, together and first WE eDAQ Potentiostats... -
Page 55: Using Multiple References And Auxiliaries
In this case you should use a set of three electrodes (working, reference, auxiliary) in each reaction vessel. Each QuadStat channel behaves as a separate potentiostat. Independent signals can be applied at each QuadStat channel E in connector, if desired, so that different experiments can be run in each reaction vessel. -
Page 56: First Use
The resulting current signal should obey Ohm’s law: I = E/R so that with a 1 MΩ test resistance, R, an applied potential, E, of 1 V should produce a current, I, of 1µA, while other potential settings eDAQ Potentiostats... - Page 57 Drag ticks and labels Figure 4–9 Start/stop scrolling to adjust axis scaling Accessing the QuadStat controls with Chart Select input range software (Windows). Select low- pass filter Select QuadStat from the Channel Set mains Function pop-up Current signal filter menu display area Invert signal Select cell...
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Page 58: Quadstat Control Window
Windows computer, and Figure 4–10 on a Macintosh computer. These windows control the various current ranges and filtering options for the QuadStat. With Scope software, the corresponding controls are shown in Figure 4–11. eDAQ Potentiostats... - Page 59 Signal Display The current signal is previewed scrolling across the display area. Note that the signal is not being recorded to hard disk at this stage, and that when the window is closed the signal trace is lost. You can stop/start the signal scrolling by clicking the Pause/Resume button You can shift or stretch the vertical Amplitude axis to make the best use of the available display area.
- Page 60 Potential slider control can be used to adjust the potential. When you close the control dialog (using EChem software) the QuadStat will revert to Standby mode until the Start button is clicked to begin a scan. If you are using Chart or Scope software, the QuadStat will eDAQ Potentiostats...
- Page 61 remain in Real mode when the dialog is closed — this allows you to start and stop recording data while the electrodes remain active, which allows periodic recording of the signal from amperometric biosensors or in vivo electrodes without disturbing the environment around the electrodes.
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Page 62: Quadstat Potential Window
Applied Potential controls, page 57, in the QuadStat Control Window, Figure 4–9 on page except that adjustments can be made while recording is in progress. Figure 4–12 The QuadStat Applied Potential controls with Chart software. eDAQ Potentiostats... -
Page 63: Maintenance
Macro feature of Chart so that the working electrode potentials can be altered at predetermined times. Please consult the Chart Software Manual, installed in the eDAQ Documentation folder on your hard disk, for more information about the use of Macros. - Page 64 Potentiostats...
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Page 65: Techniques
Chart Software Manual and Scope Software Manual (which are installed as pdf files in the eDAQ Documentation folder on your computer hard disk. Also discussed is the use of the Potentiostat when configured as a galvanostat. Additional experiments such as current–sampled staircase linear sweep,... -
Page 66: Introduction
NOTE This potential difference is determined by a ‘command voltage’ which is The QuadStat also has sent from the e-corder output to the ‘E In’ connector of the Potentiostat, internal potential Picostat, Figure 3–3, on page 29, Potentiostat, Figure 2–4, on page 9... -
Page 67: Linear Scan Techniques
Linear Scan Techniques Linear sweep or cyclic voltammetry are usually best performed with EChem software. However, Scope also incorporates Stimulator… and Output Voltage… commands which can be used to control the analog output of the e-corder to create a waveform suitable for these techniques (albeit less conveniently than with the EChem software). - Page 68 Stimulator (applied potential waveform) controls Figure 5–1 Scope Setup menu. Use the Output Voltage… command to set the baseline potential Figure 5–2 Using the Scope Stimulator Up and Down command. Figure 5–3 Using the Scope Stimulator Triangle command. eDAQ Potentiostats...
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Page 69: Chronoamperometry With Chart
For experiments involving sudden changes in potential you should use the full bandwidth of the Potentiostat or Picostat, or QuadStat (that is, if possible, do not use the low-pass filters) or the response of the current signal may be modified by the low-pass filter time response characteristics. -
Page 70: On Windows Computers
Chart software can be used to set a constant voltage of up to ±10 V (which is known as the command voltage) from the e-corder Output. This is sent to the Picostat or Potentiostat, or QuadStat, via the ‘E In’ input cable, which then applies this potential across the reference and working electrodes. - Page 71 Figure 5–4 Chart Setup menu (Windows). Use the Stimulator command to access the Stimulator (applied potential waveform) controls, Figure 5–5 & Figure 5–6 Select stimulator mode Figure 5–5 Chart Stimulator (waveform output) controls (Windows). Select output range Enter exact values as text. Use zero amplitude for constant output Baseline control can...
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Page 72: On Macintosh
±2.5 V, or pulsed waveforms, then you can use the Chart Stimulator controls as described below. Chart software can be used to output a constant potential (up to ±10 V) which the Potentiostat, Picostat, or QuadStat will apply at the working electrode. These controls are accessed through the Setup menu, Figure 5–7. - Page 73 The Chart software Stimulator command (in the Setup menu) can also be used to set up pulses, stepped pulses, and staircase ramp waveforms for the Potentiostat or Picostat. See the Chart Software Manual for more details. You can also use the Timed Events feature (Setup menu) to adjust the current at predetermined time intervals after the start of recording.
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Page 74: Analysis Of Chronoamperometry
Cottrell equation, (see Appendix D for definition of terms) nFAC D ----------------------- - 1000 πt It is usually easier to first simplify the Cottrell equation thus: ---- - where a is treated as an empirical constant to be determined. eDAQ Potentiostats... - Page 75 Figure 5–11 Typical chronoamperometric data, analyzed using the Arithmetic channel calculation and the X–Y window. Typical experiment with 1/√t data calculated on Channel 3 using the Arithmetic channel Region of ideal linear response Cottrell graph of current versus 1/√t prepared in the XY Window.
- Page 76 This allows for the errors in the estimation of time zero, and the fact that the Potentiostat has a finite bandwidth (and so the current signal will take a small amount of time to register a true value after a sudden change in potential).
- Page 77 Figure 5–12 Fitting a Cottrell equation to data with the Curve Fit extension. At the time of writing the Define the Cottrell Curve Fit extension is relationship as a new only available for Chart equation for Macintosh. First lock in a value for c, then try guesses for a and b until an approximate fit is obtained Usually use ‘t=0...
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Page 78: Chronoamperometry With Scope
Curve Fit extension are installed. Remember to operate the Potentiostat or Picostat at full bandwidth (that is do not use the low-pass filters if possible) or else your results may be dominated by the low-pass filter response! Chronoamperometry with Scope... -
Page 79: Chronocoulometry
current signal may be dominated by the low-pass filter time response characteristics. The base potential is adjusted with the Output Voltage… command (Setup menu) shown in Figure 5–13. A potential that will cause the reaction to proceed (and the period for which it will be applied) is set using the Stimulator command. - Page 80 Chart Computed Input integration (Windows). Figure 5–15 Online integration of the current signal using Chart Computed Input integration (Macintosh). Figure 5–16 Integration of the current signal using Scope Computed Functions. Select Integrate in the Function menu eDAQ Potentiostats...
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Page 81: Chronopotentiometry
For this type of experiment it will be necessary to run the Potentiostat in Galvanostat mode with Chart or Scope software. For correct operation make sure that the ‘CH 1 (I)’... - Page 82 (error) in the system. If you are trying to measure the potential of a system under zero current conditions then it would generally be more accurate to use a zero current potentiometer (or pH meter) than a galvanostat, or use the Potentiostat in High Z mode, page...
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Page 83: Chart Software On Windows Computers
5–19. Always select an appropriate current range for your system. While it is possible to set an applied current of up to 100 mA, the Potentiostat/ Galvanostat cannot supply a potential much greater than ±10 V. Even relatively small applied currents, with a highly resistive load, may require potentials in excess of this. -
Page 84: Chart Software On Macintosh
25 nA use the 100 nA range setting for best results. Chart software on Macintosh Galvanostat mode of operation is accessed by choosing the Potentiostat command in the Channel Function pop-up menu to open the control window. Turn on the Galvanostat and Dummy radio buttons, Figure 5–20. - Page 85 It is likely that there will be a small residual offset at this setting which will cause the Potentiostat/ Galvanostat to go off scale (over 10 V) in Standby mode (as it is connected to the relatively low resistance 10 Ω...
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Page 86: Scope Software
Consult the Chart Software Manual for more details of the Output Voltage, Stimulator, and Timed Events features. Scope software Operation of the Potentiostat as a Galvanostat with Scope software is similar to using Chart software (Macintosh version), see page However, a wider variety of applied waveforms can be generated with the Scope Stimulator command. -
Page 87: Controlled Current Electrolysis
Controlled Current Electrolysis These techniques are essentially the same as Chronopotentiometry, page 77, and require the use of a galvanostat. The Potentiostat, when Chapter 5 — Techniques... -
Page 88: Amperometric Sensors
Your will also need to determine whether the sensor is of a two or three electrode configuration. The Potentiostat (up to 100 nA), Picostat (up to 100 nA), and QuadStat (up to 1 mA) can be used in three electrode... -
Page 89: Biosensors
Biosensors Biosensors are often amperometric sensors and so can be used with the Picostat, QuadStat, or Potentiostat which can then be referred to as ‘biosensor meters’. The first step is to establish the polarising voltage and current measurement requirements of your sensor. -
Page 90: Microdialysis Sensor
However, depending on the current requirements of your oxygen sensor, the Potentiostat, QuadStat, or Picostat may be a suitable alternative to a standard meter as they have adjustable sensitivity and can be matched to a wide range of current signal requirements. In addition you can use them to alter the polarising voltage to ‘fine tune’... -
Page 91: Nitric Oxide (No) Sensors
Most oxygen sensors exhibit a slow response time and will take at least several seconds to stabilise. Thus you would normally employ a 1 – 10 Hz filter setting on the Potentiostat, QuadStat, or Picostat in order to minimise any electrical noise. The Mains Filter setting can also be employed to further reduce mains hum. - Page 92 Use the Chart software Multiple Point Calibration extension which can be downloaded from the eDAQ web site at www.edaq.com. The QuadStat also has the ability to zero (or offset) a background current signal which can be of use when trying to amplify small peaks...
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Page 93: A Technical Aspects
This appendix describes various technical aspects of potentiostat construction — however, you do not need to understand this material to use the Potentiostat, Picostat or QuadStat. Please note that this information is not intended as a service manual and that user modification of the equipment voids your rights under warranty. - Page 94 Interface C Output Online The Potentiostat is fitted with an internal 1 MΩ dummy cell for use in potentiostat or galvanostat mode. The dummy cell is physically connected whenever the ‘Real cell’ mode is not being used. The Potentiostat has gain ranges at decade intervals from 1 nA/V to 10 mA/V, provided by an I to V convertor and PGA.
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Page 95: Picostat
Picostat The Picostat is designed to function in potentiostatic mode only, that is it cannot be used as a galvanostat. A block diagram of its construction is shown in Figure A–2. The Picostat is powered by regulated +17 V, –17 V and +8 V DC lines from the e-corder, see Figure 3–3 on page 29. -
Page 96: Quadstat
QuadStat The QuadStat is comprised of four subunits which function in potentiostat mode only — that is the QuadStat cannot be used as a galvanostat. A block diagram of the QuadStat construction is shown in Figure A–3. - Page 97 Back Panel Front Panel Overload Detector Figure A–3 Overload Block diagram of the Power Amp Subtractor E In QuadStat, Channel 1. (Command Auxiliary Gain voltage) – E Out Ref Amp Shield Error Voltage ∑ (Reference – Hi Z voltage) Reference I to V Low–pass Filter I Out...
- Page 98 DC power allows its use inside Faraday cages. Multiple–electrode potentiostat designs, for sensor work, have been reported in “Development of a computer controlled multichannel potentiostat for applications with flowing solution analysis”, Tang Fang, Michael McGrath, Dermot Diamond, and Malcolm R. Smyth, Analytica Chimica Acta, 305, 347-358, 1995.
- Page 99 • If possible, change cables and try again. If a second cable works and you find that the first cable is faulty, you should contact eDAQ for a replacement. • If you are using EChem software, check that the ‘E In’ cable is connected to the e-corder output and the ‘I Out’...
- Page 100 (if available). If the Online indicator fails to light on the second e-corder, the Potentiostat, Picostat, or Quadstat, may be faulty — contact eDAQ. If it works correctly on a second e-corder then the first e-corder may be faulty — contact eDAQ.
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Page 101: B Troubleshooting
(i.e. a peak may be occurring at 0.5 V when it should be at –0.5 V). • Check that you are connected to the correct Output (+ or –) of the e-corder. See Connecting the Potentiostat, page 11, or Connecting... - Page 102 Particularly check the electrode cables: cables age, especially at the alligator clips where they are subject to mechanical wear. Use a multimeter to ensure that the clips are still in good electrical contact with the correct pins in eDAQ Potentiostats...
- Page 103 Ideally the reaction vessel (and even the Potentiostat or Picostat) should be enclosed by a Faraday cage. A Faraday cage (or other electrical shielding) is almost always required when measure small currents (which is usual with the Picostat).
- Page 104 Potentiostats...
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Page 105: C Specifications
A P P E N D I X Specifications Potentiostat Power Amp Compliance voltage: > 10 V Output current: ±100 mA maximum Current limit: ±200 mA Slew rate: 3 V/µs Electrometer Input resistance: Ω Input bias current: < 1 pA @ 25˚C Input voltage: ±10 V maximum... - Page 106 Current Measurement and Control Current Range Setting Potentiostat gain (µA/V) ±100, 50, 20 mA 10 000 ±10, 5, 2 mA 1 000 ±1 mA, 500, 200 µA ±100, 50, 20 µA ±10, 5, 2 µA ±1 µA, 500, 200 nA ±100, 50, 20 nA...
- Page 107 50 × 76 × 260 mm 1.96 × 3.0 × 10.2 inches Weight: 0.8 kg (1.8 lb) Operating conditions: 0 – 35˚C 0 – 90% humidity (non-condensing) eDAQ reserves the right to alter these specifications at any time. Appendix C — Specifications...
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Page 108: Picostat
< 20 µV/˚C Control Port C input and output: Male and female DB-9 pin connectors. Provides control and power to the Picostat. Power requirements: ±17 V DC, ~ 20 mA +8 V DC, ~ 20 mA ~ 1 W quiescent eDAQ Potentiostats... - Page 109 50 × 76 × 260 mm 1.96 × 3.0 × 10.2 inches Weight: 0.8 kg (1.8 lb) Operating conditions: 0 – 35˚C 0 – 90% humidity (non-condensing) eDAQ reserves the right to alter these specifications at any time. Appendix C — Specifications...
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Page 110: Quadstat
Drift with temperature: < 10 µV/˚C Control Port C input and output: Male and female DB-9 pin connectors. Provides control and power. Power requirements: ±17 V DC, ~ 20 mA +8 V DC, ~ 20 mA ~ 0.6 W quiescent eDAQ Potentiostats... - Page 111 60 × 150 × 200 mm 2.4 × 5.9 × 7.9 inches Weight: 1.5 kg (3.3 lb) Operating conditions: 0 – 35˚C 0 – 90% humidity (non-condensing) eDAQ reserves the right to alter these specifications at any time. Appendix C — Specifications...
- Page 112 Potentiostats...
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Page 113: D Electrochemical Equations
= potential at current peak for cathodic scan (V) = half potential as determined by cyclic voltammetry (V) 1 2 ⁄ n = the number of electrons transferred to (or from) the substrate molecule A = area of the exposed surface of the electrode (cm eDAQ Potentiostats... - Page 114 Nonetheless there may still be an appreciable uncompensated resistance which will cause to become larger – than predicted, the peaks to be broader, and the peak currents to be smaller. eDAQ Potentiostats...
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Page 115: Chronoamperometry
Chronoamperometry The Cottrell Equation When chronoamperometry is performed on an unstirred solution at a planar electrode the faradaic current response is described by the Cottrell equation 1 2 ⁄ nFAD ---------------------------------- - 1 2 ⁄ 1 2 ⁄ 1000π where n = the number of electrons transferred to (or from) the substrate molecule F = Faraday's constant, 96485 C/mol... -
Page 116: Chronocoulometry
Thus a plot of Q versus t should produce a straight line with an intercept of k, which in turn can be defined as: k = nFA Γ where Γ = surface concentration of adsorbed substrate (mol/cm = double layer charging. eDAQ Potentiostats... -
Page 117: Index
Bridge Amp 2 differential pulse voltammetry 61 dissolved oxygen sensor 86 Dummy cell calibration Potentiostat 18 multiple point 85 QuadStat 56 non–linear 85 potentiostat current signal 19 two point linear 85 ZRA current signal 19 checking procedure 3 eDAQ Potentiostats... - Page 118 Potentiostat 2 galvanostat 62 QuadStat 2 setting current values 77 eDAQ potentiostats 1 galvanostat mode 77 electrochemical equations 109 Potentiostat 16 Potentiostat, electrode connection 7 electrode cable Picostat 27 GP Amp 2 Potentiostat 7 ground loop 10 QuadStat 42 grounding connector...
- Page 119 C connector Picostat 29 pH Amp 2 Potentiostat 10 QuadStat 46 Picostat 2 input amplifier 13 polarity Picostat 32 integrated Cottrell equation 112 Potentiostat 12 iR Compensation 103 QuadStat 49 Potentiostat 20 polyaniline 83 polypyrrole 83 potential overload 84 lead wire capacitance 26...
- Page 120 Standby cell Potentiostat 18 QuadStat 56 static discharge 25 Timed Events 69 two-electrode operation Picostat 27 Potentiostat 15 Potentiostat, electrode connection 7 QuadStat 42 voltammetry cyclic 61 differential pulse 61 fast cyclic 63 fast linear sweep 63 linear sweep 61...
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Page 121: License & Warranty
You have the non-exclusive right to use the supplied eDAQ software (Chart, Scope etc). Your employees eDAQ Pty Ltd warrants the Potentiostat or Picostat, to or students, for example, are entitled to use it, be free of defects in material and workmanship for provided they adhere to this agreement. - Page 122 Jurisdiction eDAQ Pty Ltd is bound by the laws of New South Wales in Australia, and any proceedings shall be heard by the Supreme Court of New South Wales in Australia.
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