Palm Sens User Guide Chapter 3

Chapter 6 - PalmTime program The PalmTime program provides the possibility to measure current as a function of time. The applicable methods are: - Amperometric detection - Pulsed amperometric detection - Fast amperometry AD PAD FAM The sequence of a measurement is: - Apply Econd the conditioning potential, if t cond is not zero. - Apply Edep the deposition potential, if t dep is not zero. - Apply E or Eeq and wait t eq seconds - Start the measurement. The measured points are displayed on-line. - If the cell must remain switched on, E st.by is applied, otherwise the cell is switched off. After the measurement the measured curve is smoothed (see ‘Instrument’ → ‘Settings’) and either peaks or stationary current levels are detected using the parameters specified in ‘Instrument’ → ‘Settings’. Ch. 6.1 Menus File menu Fig. 6.1 – File menu 1. 2. 3. 4. 5. 6. Load method allows loading a predefined set of parameters for the measurement and analysis. Save method allows saving a defined set of parameters for the measurement and analysis. Load curve gives the possibility to load a measured curve. Save curve gives the possibility to save the curve measured with the sample. Load calib. curve Save calib. curve 7. 8. 9. Add to recordfile writes the results of the determination to the file called RecordFile. This text file can easily be imported in Pocket Word and synchronized with the PC. Delete allows removing files from the Pocket PC. Exit ends the program. When a filename has to be specified the soft keyboard has to be used. Where relevant the ‘Sample name’ as well as the ‘Sensor name’ is shown. Edit Fig. 6.2 – Edit menu 1. Method is used to specify the electrochemical parameters for all measurements. The parameters are described in the next paragraph. Two textboxes are available which are normally used to specify the ‘Sample name’ as well as the ‘Sensor name’. Values of parameters are changed by using the horizontal scrollbar in three different ways. The scrollbar can be moved. The arrows are used to change the value by the smallest possible step. The space between the scrollbar and the arrows is used to change the value by large steps. The measurement technique is chosen from the list shown after tapping the down-arrow. After modification of parameters the Validate button has to be tapped. Fig. 6.3 – Window with parameters for the determination. 2. Standards is used to specify the required parameters for the determination. a) Analyte is used to give any name. b) Unit of concentration: any text can be specified. It is not used for the calculations but only to report the results. c) Standards specify the concentration of the analyte. d) Signal. If dc-current is specified the program searches for stationary dc-levels. Specify ‘Peak’ when the current versus time plots will show peaks. e) Reaction determines whether peaks or current levels or positive (Oxidation) or negative (Reduction). Plot Fig. 6.4 – Plot menu 1. 2. 3. 4. 5. 6. 7. 8. Plot shows the plot window on the display Automatic scaling is used to change the scaling of the y-axis automatically using all displayed curves. Manual scaling allows manual specification of y-top and y-bottom. Mark new scaling allows rescaling the plot with the stylus. Tap the stylus on lower left point and move it to the upper right point for the new graph. Cal. curve is selected when dc-current levels or peak heights are determined. A plot is made of current levels or peak heights versus a concentration calculated from the specified values in the window ‘Edit’→ ‘Standards’. Plot Q vs t Redraw makes a new plot with the recent curves measured for the sample and if present also the multiplexer curves and detects the peaks or current levels in the curves again. This option is also useful when new peak detection parameters have been specified in the window ‘Instrument’→ ‘Settings’. Save picture is used to save the plot as a bitmap file. This file can be transferred to a PC and the picture can be imported in a document. Measure Fig. 6.5 – Measure menu 1. 2. 3. 4. 5. 6. 7. 8. Start is tapped for a new measurement. Start (new plot) is used when a new measurement is made in a new plot. Clears any existing plots. Calibrate is tapped when a measurement of a calibration curve is started. Null is used to set the offset of the current or potential measurement. Displayed points are corrected for this offset. No offset will set the offset current to 0 A respectively. Hold/Continue is tapped when the measurement is halted or continued. Abort is used to stop the measurement. Delete all curves removes all measured curves from the memory. Instrument Fig. 6.6 – Instrument menu The PalmTime and PalmScan ‘Instrument’ menu are identical. See for description pages 24-28. Ch. 6.2 Method parameters The amperometric or potentiometric are specified in the window ‘Method’. Fig. 6.9 – The method parameters Left window with potentials: E Potential during measurement (in AD) or applied before pulse is given (in PAD). The applicable range of the potential is –2 V to +2 V. E eq Equilibration potential which is applied before the measurements starts (FA only) E pulse Potential in pulse. Note that this value is not relative to E, given above. In FA the current is continuously sampled during this stage. E cond Potential applied before the deposition stage is started. Is only relevant when t cond > 0 s. E dep Potential applied during the deposition stage. Is only relevant when t dep > 0 s. E st.by Potential applied after a measurement, if the cell is not switched off (see ‘Instrument’ → ‘Settings’). Right window with time related parameters: Interval Time between two measurements t pulse The pulse time in PAD and FA t run Total time of measurement. Measure 1: i(dc) measurement is performed at potential E 2: i(pulse) measurement is performed at potential E pulse 3: i(dif) measurement is i(dc) – i(pulse) t cond Conditioning time. t dep Deposition time t eq Equilibration time. During this stage Eeq or E is applied. Ch. 6.3 Multiplexer If the use of the CH8 multiplexer is enabled in PSConfig program, the menu’s in PalmTime are extended with several extra options: File menu: 1. Load curves (CH8); load up to 8 measured curves 2. Save curves (CH8); save up to 8 measured curves Method menu: 1. Multiplexer; specify which channels are measured and whether they should be measured successively or scanned at each time. These parameters are also stored in the method file. If the multiplexer method ‘Scan channels at each time’ is selected, only the technique amperometric detection can be used. Fig. 6.10 – Multiplexer window Plot menu: 1. Show curves; determine which measured channels are shown in the plot window. The options to calculate, save and load calibration curves are disabled when using the multiplexer. Chapter 7 - Specifications PalmSens Instrumental specifications Controlled potential mode (potentiostat) - dc-potential range ±2V - compliance voltage ±7V - dc-potential resolution 1 mV - dc-offset error 2 mV - accuracy ≤ 0.2 % - ac-potential amplitude 1 mV to 250 mV - current ranges 1 nA to 1 mA (7 ranges) - maximum current ± 10 mA ± 2 mA measured - current resolution 0.1 % of current range 1 pA on lowest current range - accuracy ≤ 0.3 % of current range at 100 nA to 1 mA ≤ 0.5 % at 10 nA and ≤ 1 % at 1 nA all with additional 0.2 % offset error Controlled current mode (galvanostat) - current ranges 1 µA to 1 mA -2 to + 2 times selected current range - dc-current range - dc-current resolution 0.1 % of selected current range - dc-offset error ≤ 0.2 % ≤ 0.4 % - current accuracy - maximum output voltage ± 7V General: - electrometer amplifier input - rise time Keypad Display Dimensions Temperature range Weight Power Interfacing Default serial mode: > 100 Gohm // 4 pF approx. 50 µs ▲►▼◄ ENTER ESC and Power (7 keys) 4 lines of 16 characters with backlight 155 mm x 85 mm x 35 mm 0º C to + 40º C 0.43 kg 2 AA cells NiMH 1800 mAh or 2100 mAh for 6-8 hours operation. battery charger included (6 V- 1500 mA) Serial: RS232 to Pocket PC (preferably Compaq or HP iPAQ) or Bluetooth 57600 baud, 8 bits data, no parity, 1 stopbit. A Bluetooth module is available as an option. External I/O Miniature DIN connector: 1 analog output and 1 analog input channel (0 V 4.096 V) 3 digital output lines 1 digital input line Maximum rating: -0.3 V to 5.3 V Optional expansion: CH8 multiplexer for multisensor applications up to 8 channels All electrodes are either at same potential or all not-selected electrodes are at open-circuit potential. In specific cases the instrument can be expanded with customer specified module. Contact Palm Instruments. Ch. 7.1 Sensor and miniDIN connectors Pinout of miniature DIN connector: Front view of male plug: Solder side of male plug 7● ● ●9 3● ● ● ●6 1● ● 2 9● ● ●7 6● ● ● ●3 2● ● 1 pin 1 Vadapter (6 V- 1.5 A) pin 2 analog ground pin 3 d0 digital output (maximum current 5 mA source or sink) pin 4 d1 digital output (maximum current 5 mA source or sink) pin 5 d2 digital output (maximum current 5 mA source or sink) pin 6 d0 digital input pin 7 auxiliary analog input pin 8 auxiliary analog output (advised resistive load > 10 kohm) pin 9 5 V digital power line (maximum current 100 mA) shield digital ground Maximum ratings: Digital input and output lines: Analog input and output lines: -0.3 V to 5.3 V -0.3 V to 5.3 V Pinout of sensor connector: Front view of male plug: Solder side of male plug: υ 5● ● 1 4● ● 2 3● 1. 2. 3. 4. 5. υ 1● ● 5 2● ● 4 3● WE: red connector is working electrode AGND: green connector is ground RE shield: (not connected in default plug) CE: black connector or counter electrode RE: blue connector or reference electrode IMPORTANT: The shield of the cable must make contact with the metal case of the sensors connector. Appendix 1 Pocket PC files All files are ASCII and can easily be transferred from the Pocket PC to the PC and vice versa by using Windows Explorer. The files are stored in the directory: My Pocket PC\My Documents\PS Data The programs and default method files are stored in: My Pocket PC\Program Files\PalmSens File extensions Method files: Sample curve: PalmScan program .pms .pss Analysis: RecordFile .pds .psw PalmTime program .pmt .pst .mux (for CH8 files) .pdt .psw The method file contains all specified parameters given in the windows available under the menu ‘Method’ as well as shown in ‘Settings’ from the ‘Instrument’ menu. The ‘sample curve’ (as well the ‘analysis’) files contain measured data of potential and current or time and current. After transferring them to the PC, these files can easily be imported in Excel or other graphical programs for further data analysis. The ‘Sample curve’ file is also compatible with Autolab software. The file extension has to be changed to .oew and the file with the procedure parameters has to be created by the Autolab program. Appendix 2 Default methods The default methods for the PalmScan and PalmTime programs are stored in the files called PalmScan.pms and PalmTime.pmt. Each time a program is ended, this file is overwritten. The software is installed with some default methods. The next files are described in Ch. 4. PSNoiseTest Method to check the noise level using the testsensor. PSDiffPulse Method to measure a peak using the testsensor. PSSimulation Method which is used without PalmSens. The curves are not measured but simulated. The parameters can be used as an example for the determination of heavy metals using anodic stripping square wave voltammetry. PSTime Method to measure current versus time using the testsensor. It can also be used to check the noise level. Other methods with typical voltammetric parameters are: PSCV PSSWV PSSCP PSacV Method for cyclic voltammetry Method for square wave voltammetry Method for potentiometric stripping analysis Method for ac voltammetry Appendix 3 Battery maintenance In case the battery capacity decreases it is advised to switch on PalmSens and wait until it switches off automatically. After charging the batteries, their capacity might be restored again. Warning: Do not charge the batteries when the ambient temperature is below 0ºC or above 40ºC. Charging is done most efficiently in the range of 10ºC to 30ºC. Do not store the instrument with batteries in places where the ambient temperature is below 0ºC or above 40ºC. Do not connect the charger with reversed polarity. In case the batteries have to be exchanged follow the next steps. Switch off PalmSens and remove all cables. Remove the screws at the right-hand side of PalmSens using a proper screwdriver. Gently take out the batteries, unplug the connector. Connect the new batterypack and place the pack back in the instrument and tighten the screws again. Do not use any force. Note: the batterypack must be obtained from Palm Instruments. Ordering code: PART-BATT1. Appendix 4 Updating PalmSens firmware IMPORTANT: It is essential that PalmSens is not switched off during the process of updating the firmware. Be sure that the batteries are full or that PalmSens is connected to the ac-adapter. Updating from Pocket PC The firmware of PalmSens can be upgraded by the Pocket PC with installed PalmSens software. Connect PalmSens to the Pocket PC by means of the serial cable. IMPORTANT: The firmware update is not possible using the Bluetooth dongle. Tap ‘Start’ and select ‘Programs’. Tap the program ‘PSConfig’ and tap the button ‘Update firmware of the PalmSens instrument’. Pocket PC display when PalmSens is not properly connected. As soon as PalmSens is recognized, the display shows a green sign with the message ‘PalmSens is connected’. Tap the ‘Download’ button to update the firmware. Updating from PC or laptop The requirements are: - PalmSens CD-ROM or downloaded files from www.palmsens.com. - Serial download cable (standard null modem cable, female-female) or USB cable (delivered with the PalmSens PC software) to connect PalmSens to the Laptop or PC. Plug the serial/USB cable in the connector of the PC as well as PalmSens. Switch on PalmSens and wait until the display shows ‘PalmSens Vs#.##’. If you have the PSDownload program already installed, you can skip the next paragraph. Installing PSDownload The PSDownload setup program is located on the PalmSens CD-ROM in ‘\PSDownload\Setup.exe‘. You can also run the PSDownload setup using the auto run menu which appears when you insert the CD-ROM. Downloading new firmware to PalmSens Run the program PSDownload from the installed location, the default location is: ‘c:\Program Files\PSDownload\’. You can browse to this location using ‘Run’ from the ‘Start menu’ and click ‘Browse’ or using ‘Windows Explorer’. You can also run PSDownload from the ‘Start’ menu. When you run the program and PalmSens is properly connected you should see the following window: Screenshot of PSDownload running in Windows XP. The program leads you through the downloading procedure. If you want to download a different version to PalmSens (a PS.HEX file), you should overwrite the existing PS.HEX in the directory where PSDownload is installed. The default installation folder is ‘C:\Program Files\PSDownload\’ After the firmware has been updated PalmSens is re-calibrated automatically.