Metrohm 946 Portable VA Analyzer Manual
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Metrohm 946 Portable VA Analyzer Manual

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946 Portable VA Analyzer
2.946.00x0
Manual
8.946.8003EN

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Summary of Contents for Metrohm 946 Portable VA Analyzer

  • Page 1 946 Portable VA Analyzer 2.946.00x0 Manual 8.946.8003EN...
  • Page 3 Metrohm AG CH-9100 Herisau Switzerland Phone +41 71 353 85 85 Fax +41 71 353 89 01 info@metrohm.com www.metrohm.com 946 Portable VA Analyzer 2.946.00x0 Manual 8.946.8003EN 2019-05-31 zu...
  • Page 4 Technical Communication Metrohm AG CH-9100 Herisau techcom@metrohm.com This documentation is protected by copyright. All rights reserved. This documentation has been prepared with great care. However, errors can never be entirely ruled out. Please send comments regarding possible errors to the address above.

  • Page 5: Table Of Contents

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ Table of contents Table of contents 1 Introduction Instrument description ............1 Intended use ................. 1 Safety instructions ..............2 1.3.1 General notes on safety ............2 1.3.2 Electrical safety ................ 2 1.3.3 Recycling and disposal ............. 3 Symbols and conventions ............ 3 2 Overview of the instrument Potentiostat ................
  • Page 6 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ Table of contents Carrying out the determination of As(total) according to Application Bulletin 416 ..........33 5.2.1 General operation ..............33 5.2.2 Initial electrode preparation ........... 35 5.2.3 Running the determination of As(total) ........36 5.2.4 Cleaning of the scTRACE Gold electrode ........ 38 6 Maintenance Removing the scTRACE Gold ..........
  • Page 7 Figure 3 946 Portable VA Analyzer - scTRACE Gold measuring stand over- view ....................6 Figure 4 946 Portable VA Analyzer - SPE measuring stand overview ....7 Figure 5 Details SPE holder ................8 Figure 6 Portable VA Analyzer software - overview (default workplace lay- out) ....................

  • Page 9: Introduction

    Gold electrode. The instrument is suitable for processing various chemicals. Therefore, the use of the 946 Portable VA Analyzer requires the user to have basic knowl- edge and experience in handling toxic and caustic substances.

  • Page 10: Safety Instructions

    Electrical safety The electrical safety when working with the instrument is ensured as part of the international standard IEC 61010. WARNING Only personnel qualified by Metrohm are authorized to carry out service work on electronic components. Supply voltage WARNING An incorrect supply voltage can damage the instrument.

  • Page 11: Recycling And Disposal

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 1 Introduction 1.3.3 Recycling and disposal This product is covered by European Directive 2012/19/EU, WEEE – Waste Electrical and Electronic Equipment. The correct disposal of your old instrument will help to prevent negative effects on the environment and public health. More details about the disposal of your old instrument can be obtained from your local authorities, from waste disposal companies or from your local dealer.
  • Page 12 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 1.4 Symbols and conventions Note This symbol marks additional information and tips. ￭￭￭￭￭￭￭￭...

  • Page 13: Overview Of The Instrument

    The following figures show details of the potentiostat and the measuring stand of the 946 Portable Analyzer. Potentiostat Figure 1 946 Portable VA Analyzer - potentiostat front view Status LEDs Electrode cable connector Connection socket for the cable connection Power on...

  • Page 14: Measuring Stand Sctrace Gold

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 2.2 Measuring stand scTRACE Gold Measuring stand scTRACE Gold Figure 3 946 Portable VA Analyzer - scTRACE Gold measuring stand overview Base plate (6.02708.020) O-ring (6.01408.000) Measuring vessel (6.01412.000) Transparent ring (6.02708.030) Pipetting opening Stirrer (6.01204.000) Measuring head scTRACE Gold Electrode cable connector (6.01256.010)

  • Page 15: Measuring Stand Spe

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 2 Overview of the instrument Measuring stand SPE Figure 4 946 Portable VA Analyzer - SPE measuring stand overview Base plate (6.02708.020) O-ring (6.01408.000) Measuring vessel (6.01412.000) Transparent ring (6.02708.030) Pipetting opening Stirrer (6.01204.000) Measuring head SPE (6.01256.020) Electrode cable connector...

  • Page 16: Figure 5 Details Spe Holder

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 2.3 Measuring stand SPE Figure 5 Details SPE holder Shaft SPE holder Electrical connector for SPE Connection socket for the screen-printed electrode Positioning support Silicone seal for SPE electrode shaft (6.1244.060) Supporting ring for SPE electrode shaft Nut for SPE electrode shaft (6.1241.210) (6.1241.200) ￭￭￭￭￭￭￭￭...

  • Page 17: Overview Of The Software

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 3 Overview of the software 3 Overview of the software The following gives an overview of the software windows and menu func- tions. NOTICE More details about the software and method parameters can be found in the Portable VA Analyzer software manual (8.0105.8002EN). Figure 6 Portable VA Analyzer software - overview (default workplace layout)
  • Page 18 Opens the dialog window to load an existing determination file. Load determination By default determinations are saved in the folder %USERPROFILE%\Docu- ments\Metrohm\Portable VA Analyzer\Determination. Example determinations can be found in the folder %USERPROFILE%\Docu- ments\Metrohm\Portable VA Analyzer\Examples\Determinations. Opens the dialog window to load an existing method file.
  • Page 19 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 3 Overview of the software Establish a connection between the software and the instrument via USB (see Connect chapter 4.4, page 22). Inactive when an instrument is connected. Disconnect the software from the instrument. Disconnect Inactive when no instrument is connected. Start the determination.
  • Page 20 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ The calibration curve of each substance defined in the method is shown in ￭ an individual subwindow with the name 'Substance name' calibration. Edit method parame- Open the dialog window to edit method or determination parameters. The ters parameters can be found on four tabs: General ￭...
  • Page 21 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 3 Overview of the software Display of time, potential and current related to the voltammetric measurement. Live curve (6-6) Live display of the currently measured voltammogram. Subwindow in the Default workplace and Mosaic workplace layout. In the Tabs workplace layout it is found in the Curves subwindow as separate tab.

  • Page 22: Installation

    4.1.3 Operation site The 946 Portable VA Analyzer has been designed for mobile application. CAUTION Influence of weather conditions The instrument can be damaged as a result of direct sunlight, direct exposure to water or operation at temperatures below the freezing point.

  • Page 23: Hardware Installation

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 4 Installation Hardware installation 4.2.1 Stirrer Figure 7 Assembly of stirrer This procedure equally applies for the scTRACE Gold measuring head (6.01256.010) and the SPE measuring head (6.01256.020). 1 Screw the stirrer tip (6.01204.000) onto the stirrer connector. Use the 4 mm metal wrench (6.02621.000) to keep the stirrer connector from turning.

  • Page 24: Screen-Printed Electrode (Spe)

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 4.2 Hardware installation 1 Align the arrow mark on the scTRACE Gold with the arrow mark on the measuring head. Slip the scTRACE Gold onto the electrode holder until the stop. CAUTION To avoid damage to the contact springs take care not to twist the scTRACE Gold while mounting it to the electrode holder.
  • Page 25 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 4 Installation a) Assembling the electrode holder CAUTION Before assembling the electrode holder make sure that all parts are completely dry. Check especially the connection socket for the SPE (5-2) ￭ the slot in the silicone seal (5-4) ￭ for solution.

  • Page 26: Assembling The Measuring Stand

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 4.2 Hardware installation 2 Slide the SPE straight into the slot of the silicone seal until the stop. NOTICE Tilting the electrode may damage the connection socket for the SPE behind the silicone seal. 3 Tighten the nut in a clockwise direction to fix the electrode and seal the inside of the holder against liquids.

  • Page 27: Connecting The Measuring Stand And The Potentiostat

    4.2.5 Connecting the measuring stand and the potentiostat Figure 11 946 Portable VA Analyzer - potentiostat connected to mea- suring stand Measuring stand Electrode cable (6.02135.000) Potentiostat Measuring stand and potentiostat are connected via the electrode cable (6.02135.000).

  • Page 28: Power Supply

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 4.3 Power supply Take care of the correct orientation of the plug and tighten the screw to secure the connection. 2 Plug in the female connector of the electrode cable into the connec- tion socket (3-8), (4-8) of the measuring head. Take care of the correct orientation of the plug and tighten the screw to secure the connection.

  • Page 29: Charging The Battery With Power Supply Unit

    For charging only use the supplied USB power supply unit (6.02117.000), which has been approved as accessory for use with this instrument. CAUTION The battery can only be replaced by an authorized Metrohm Service. Any attempt of unauthorized replacement will result in a loss of war- ranty. 4.3.1...

  • Page 30: Connecting The Software With The Instrument

    2 Start the Portable VA Analyzer software by double-clicking the desk- top icon or selecting the link Portable VA Analyzer under Windows start menu ▶ All programs ▶ Metrohm ▶ Port- able VA Analyzer 3 Press the ON/OFF button (2-3) on the rear side of the potentiostat to switch on the instrument.

  • Page 31: Operation

    If necessary, browse for the location of the method. Click on [Open] to load the method. The default directory for methods is %USERPROFILE%\Docu- ments\Metrohm\Portable VA Analyzer\Method . Example methods can be found in the folder %USERPROFILE% \Documents\Metrohm\Portable VA Analyzer\Examples \Methods.
  • Page 32 If necessary, browse for the location of the determination. Click on [Open] to load the determination. The default directory for determinations is %USERPROFILE% \Documents\Metrohm\Portable VA Analyzer\Determination. Example determinations can be found in the folder %USERPROFILE %\Documents\Metrohm\Portable VA Analyzer\Examples \Determinations.

  • Page 33: Running A Determination

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5 Operation NOTICE Some method parameters, e.g. voltammetric parameters, cannot be edited in a determination file. Nonetheless the reevaluation of peaks and recalculation of standard additions is still possible. For more information on the reevaluation of a determination see Chapter 5.1.4, page 28.
  • Page 34 Directories for automatic saving of determinations and reports are predefined and cannot be modified. Determination files are saved in the directory %USERPROFILE% \Documents\Metrohm\Portable VA Analyzer\Determina- tion . The file name is automatically generated from date and time of the determination start and the sample identifier and has the format YYYYMMDD-hhmmss 'Sample identifier'.det.

  • Page 35: Printing Of Result And Method

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5 Operation NOTICE Automatically saved determinations are read-only. If changes of a reevaluated determination should be saved, it has to be under a new name. 5.1.3 Printing of result and method Printing a determination result 1 Load the determination file for which the report should be printed, if not already loaded in the software.

  • Page 36: Reevaluating A Determination

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5.1 Basic software operation The PDF file with the selected report elements will be created and saved in the specified directory. Printing a method 1 Load the method file for which the parameters should be printed, if not already loaded in the software. 2 Click on or Menu bar ▶...
  • Page 37 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5 Operation NOTICE Some method parameters, e.g. voltammetric parameters, cannot be edited in a determination file. If the voltammetric parameters of the determination method should be adapted for future measurements, the parameters have to be saved first, using the function Save method as… (page 24). The new method, containing all parameters of the determination method, can then be loaded and edited.
  • Page 38 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5.1 Basic software operation NOTICE The Result unit depends on the unit of the standard solution. If the concentration of the standard solution is a mass concentra- tion, e.g. mg/L, also the result unit has to be a mass concentration, e.g.
  • Page 39 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5 Operation The determination will automatically be recalculated with the new settings. Adapting the base points for an individual curve 1 On the workplace, go to the subwindow Results and select the tab with the name of the substance for which the base point(s) should be adapted.
  • Page 40 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5.1 Basic software operation NOTICE A substance can only be contained in one standard solution. In case of multiple standards, the concentration in the other standard solution(s) has to be 0. NOTICE The Unit of the standard solution is linked to the Result unit of the final result of the substance.

  • Page 41: Carrying Out The Determination Of As(Total) According To Application Bulletin 416

    Gold, which is available for download from https://www.metrohm.com. On this website also other applications using the scTRACE Gold elec- trode and the 946 Portable VA Analyzer can be found. 5.2.1 General operation Prepare the reagents as described in Application Bulletin 416. The follow-...

  • Page 42: Figure 12 Operation Of Measuring Stand

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5.2 Carrying out the determination of As(total) according to Application Bulletin 416 NOTICE It is recommended to use only reagents of highest quality, e.g. Merck ® ® suprapur or Honeywell/Fluka TraceSelect . The water for preparation of reagents and for rinsing should have ultrapure quality (resistivity >18 MΩ·cm (25 °C), type I grade (ASTM D1193)).

  • Page 43: Initial Electrode Preparation

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5 Operation 5.2.2 Initial electrode preparation A new scTRACE Gold electrode needs to be initially activated and then cleaned before it can be used for a determination. NOTICE The procedure Activation of the scTRACE Gold should only be carried out once with a new electrode.

  • Page 44: Running The Determination Of As(Total)

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5.2 Carrying out the determination of As(total) according to Application Bulletin 416 Cleaning of the scTRACE Gold 1 Load the example method AB416 Cleaning scTRACE Gold.detp (see "Loading a method", page 23). 2 Fill 18 mL cleaning solution into the measuring vessel (3-3). Use the scaling on the vessel to measure the volume.
  • Page 45 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5 Operation NOTICE The addition of KMnO is only required if the sample contains As as well as As . If the sample only contains As , the determination can be carried out without the addition of KMnO solution. 5 Position the measuring vessel on the base plate (3-1) of the measur- ing stand.

  • Page 46: Cleaning Of The Sctrace Gold Electrode

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5.2 Carrying out the determination of As(total) according to Application Bulletin 416 NOTICE When the concentration in the sample is too high, less sample can be used for the determination. The remaining volume to the original 15 mL should be replaced by ultrapure water. Take care that the total volume at the beginning of the determination is minimum 16 mL and at the end of the determination not more than 23 mL.
  • Page 47 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 5 Operation NOTICE Extensive cleaning and multiple repetitions of the cleaning procedure can reduce the lifetime of the scTRACE Gold. CAUTION The printed parts of the scTRACE Gold are not resistant against organic solvents. Therefore, no organic solvents, not even ethanol, should be used for cleaning purposes.

  • Page 48: Maintenance

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 6.1 Removing the scTRACE Gold 6 Maintenance Removing the scTRACE Gold To prevent cross-contaminations between different applications or if the electrode performance is bad, the scTRACE Gold electrode can be replaced. NOTICE The scTRACE Gold electrode has a limited lifetime. If the performance of the electrode cannot be recovered by the cleaning procedure descri- bed in the respective application description or in Chapter 5.2.4 Clean- ing of the scTRACE Gold electrode (page 38), the electrode needs to be...

  • Page 49: Removing The Screen-Printed Electrode

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 6 Maintenance 2 If the scTRACE Gold should be used again later, put the protective cap back on the electrode to avoid damage to the gold micro-wire. 3 Hold the scTRACE Gold left and right on the splash protection as indi- cated with the green marks in Figure 13.

  • Page 50: Removing The Stirrer

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 6.3 Removing the stirrer 1 Remove the measuring head, with the transparent ring and the SPE assembled, from the measuring stand. 2 Unfasten the nut (5-6) in a counterclockwise direction (see Figure 14 a)) and remove it from the electrode holder. NOTICE The nut can be slippery when wet.

  • Page 51: Cleaning The Instrument

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 6 Maintenance Figure 15 Remove stirrer This procedure equally applies for the scTRACE Gold measuring head (6.01256.010) and the SPE measuring head (6.01256.020). 1 Remove the scTRACE Gold electrode (see chapter 6.1, page 40) or the screen-printed electrode (see chapter 6.2, page 41). 2 Remove the transparent ring (3-4), (4-4).
  • Page 52 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 6.4 Cleaning the instrument CAUTION The measuring stand is made of PETP (polyethylene terephthalate) and PMMA (polymethyl methacrylate). PETP is only conditionally and PMMA not resistant against organic solvents. Therefore, no organic solvents, such as methanol, ethanol or acetone, should be used for cleaning. Measuring head Clean the measuring head (3-7), (4-7) with a moist cloth.

  • Page 53: Troubleshooting

    ￭ The measuring solution must have a sufficient conductivity. Take care ￭ that the used electrolyte is sufficiently concentrated. Check Metrohm application documentation, e.g. Application Bulletins, for detailed information on the electrolyte. Some components of the electrolyte, e.g. organic buffers or complex- ￭...

  • Page 54: Quantification

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7.2 Hardware problems 7.1.3 Quantification The concentration of the analyte is determined by standard addition tech- nique. The following section lists some requirements for a successful stan- dard addition: The concentration of the analyte in the standard solution must be ￭...
  • Page 55 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7 Troubleshooting Problem Cause Remedy Technical failure. Disconnect the USB cable from the potentio- stat and try to switch it on again. If the green status LED indicates that the potentiostat is on, reconnect the USB cable. Potentiostat - the Battery level too low.

  • Page 56: Application Problems

    Stirrer motor jammed. Check whether it is possible to manually rotate the stirrer. If it does not rotate freely, contact your local Metrohm Service. scTRACE Gold - the Activation and/or cleaning Verify that it is necessary to clean the electrode...
  • Page 57 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7 Troubleshooting Problem Cause Remedy Exclude the outlier from the calibration ￭ curve (see "Excluding a curve from the evaluation", page 30). Random calibration points In this case, check the application: Does the peak for the analyte appear at the ￭...
  • Page 58 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7.3 Application problems Problem Cause Remedy The method parameters Check the voltammetric parameters, in particu- are not correct. lar the parameters for cyclovoltammetric and potentiostatic pretreatment. The electrode is not in a Clean the electrode as recommended in the good condition.
  • Page 59 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7 Troubleshooting Problem Cause Remedy Pipetting has not been car- The standard additions have to be carried ￭ ried out correctly. out by the same person using the same pipette. Read up on the correct pipetting in the ￭ manual of the pipette.
  • Page 60 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7.3 Application problems Problem Cause Remedy suring range the maximum current which is displayed correctly is ±4 µA. Please note that in square-wave and differential pulse measuring mode only potential differences are displayed, so the absolute measured current can be higher than what is displayed.
  • Page 61 Electrical contacts in the often, the electrical contacts in the connection SPE holder corroded. socket for the SPE can corrode. Contact your local Metrohm Service for the replacement of the SPE holder. Electromagnetic radiation Other electronic equipment in the vicinity of interferes.
  • Page 62 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7.3 Application problems Problem Cause Remedy Wrong pH. In some applications the pH of the measuring solution can be critical. Check the respective application documentation for the recommen- ded pH and measure the pH of the measuring solution. Wrong method or incorrect Check that the method and voltammetric method parameters.
  • Page 63 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7 Troubleshooting Problem Cause Remedy Electrode, electrode holder, Run the dummy cell test (see chapter 7.5, electrode cable or poten- page 66) to verify that potentiostat and elec- tiostat defective. trode cable are working correctly. Replace the electrode by a new one and repeat the determination.
  • Page 64 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7.3 Application problems Problem Cause Remedy sider the linear working range of the method (see chapter 7.4.1, page 60). The observed peak is not Adapt the evaluation so that the correct ￭ from the analyte. peak is evaluated (see Adapting the base- line parameters for all curves (page 30), Adapting the base points for an individual curve (page 31) or Excluding a curve from...
  • Page 65 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7 Troubleshooting Problem Cause Remedy The method parameters Identify the problem and adapt the voltam- are not suitable for the metric parameters and/or the electrolyte com- application problem. position. The stirrer does not work See Stirrer - the stirrer does not rotate. correctly.
  • Page 66 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7.3 Application problems Problem Cause Remedy The concentration of ana- Reduce the sample volume or use a more lyte is too high, the elec- diluted sample. Also consider the linear work- trode is overloaded. ing range of the method (see chapter 7.4.1, page 60).
  • Page 67 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7 Troubleshooting Problem Cause Remedy If a sample with low concentration is deter- ￭ mined after a sample with very high con- centrations, a cross-contamination can be expected. Run a blank determination in between the two samples to test the blank and clean the measuring cell.

  • Page 68: Some Voltammetric Troubles In Detail

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7.4 Some voltammetric troubles in detail Problem Cause Remedy Interfering substances A second peak of an interfering substance ￭ mask the analyte. overlaps with the analyte peak. It depends on the individual case whether the interfer- ence can be eliminated. More information may be available in the respective applica- tion documentation.

  • Page 69: Potential Range Of An Sctrace Gold Electrode

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7 Troubleshooting Figure 16 Good and bad standard addition curves Calibration function Peak height sample Good standard addition Bad standard addition Additions within linear working range Additions outside linear working range Standard addition calculation OK Standard addition calculation with error 7.4.2 Potential range of an scTRACE Gold electrode In this chapter the influence of chloride, oxygen and pH are described at...

  • Page 70: Figure 17 Influence Of Chloride Concentration On The Background Current Of The Sctrace Gold Electrode

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7.4 Some voltammetric troubles in detail current at positive potentials is due to the oxidation of the electrode mate- rial, in this case gold. Oxidation of the electrode material means dissolu- tion of the working electrode and as a consequence reduced lifetime of the electrode.
  • Page 71 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7 Troubleshooting NOTICE Similar effects can be observed with other anions forming complexes with the working electrode material, e.g. other halides, pseudo-halides, and hydroxides. Besides the influence on the working electrode the concentration of chlor- ide also affects the potential of the reference electrode. The following table shows the potential difference measured versus a classical Ag/AgCl reference electrode (6.0728.040;...

  • Page 72: Figure 18 Influence Of Oxygen On The Background Current Of The Sctrace Gold Electrode

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7.4 Some voltammetric troubles in detail Figure 18 Influence of oxygen on the background current of the scTRACE Gold electrode. (Measuring solution: c(H ) = 1 mmol/L, c(KCl) = 50 mmol/L) with oxygen after 5 min purging with nitrogen For a determination that means all substances which show a peak more positive than -0.2 V can be determined without purging the measuring solution.

  • Page 73: Figure 19 Influence Of Ph On The Background Current Of The Sctrace Gold Elec

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 7 Troubleshooting Figure 19 Influence of pH on the background current of the scTRACE Gold electrode. ~ pH 2 ~ pH 5 (c(KCl) = 50 mmol/L) (c(KCl) = 50 mmol/L, c(H ) = 10 mmol/L) ~ pH 12 (c(KCl) = 50 mmol/L, c(NaOH) = 10 mmol/L) For a determination that means that only substances which show a peak more positive than -0.5 V can be determined in an acid electrolyte.

  • Page 74: Dummy Cell Test

    The dummy cell (6.02813.000) is an electronic circuit simulating an elec- trochemical cell. It allows to test the potentiostat independent from elec- trodes and applications. Figure 20 946 Portable VA Analyzer - potentiostat connected to the dummy cell Dummy cell (6.02813.000) Potentiostat Electrode cable (6.02135.000)
  • Page 75 LSV_0001_sample_rep_01: (-1.0, -0.996). The first value in the brack- ets is the potential, the second value the current. NOTICE If one of these criteria is not fulfilled, contact the local Metrohm Ser- vice. ￭￭￭￭￭￭￭￭...

  • Page 76: Technical Specifications

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 8.1 Potentiostat 8 Technical specifications Potentiostat Power supply Li-ion battery (2300 mAh); USB; DC charger adapter compatible (5 V DC, 1 A) PC interface USB, RS232 Operating modes Potentiostat DC potential ± 4.096 V range Current ranges ± 1 nA to ± 10 mA (8 ranges) Maximum measur- 40 mA able current...

  • Page 77: Measuring Stand

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 8 Technical specifications Weight 480 g Housing material Corpus Aluminum alloy End cover Zinc alloy Impact protec- tion seal and decor strips Measuring stand Dimensions Length 116 mm Width 104 mm 148 mm Height Weight 464 g (scTRACE Gold) 478 g (SPE) Housing material Base plate and...

  • Page 78: I/O Connector

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 8.4 I/O connector I/O connector Table 2 I/O connector assignment Line Assignment Cable (6.02135.010) DIO 1 Blue 1 (Purge) DIO 2 Blue 2 (Digital output 2) Ground Green Safety specifications This instrument fulfills the following electrical safety requirements: CE marking in accordance with the EU directives: 2014/35/EC (Low Voltage Directive, LVD) ￭...

  • Page 79: Connection

    ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ 8 Technical specifications Connection Connection USB (version 1.1 or higher) ￭￭￭￭￭￭￭￭...

  • Page 80: Accessories

    Internet. You can download this information using the article number as follows: Downloading the accessories list 1 Enter https://www.metrohm.com/ into your Internet browser. 2 Enter the article number (e.g. 2.946.0010, 2.946.0020) into the search field.
  • Page 81 ￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭ Index Index Base plate ......6, 7 Measuring head ....... 34 Safety instructions ...... 2 Assembly ......19 Assembly ...... 15, 19 Sample size ......32 Screen-printed electrode → see SPE Cleaning ......43 Cleaning ......44 Base points ....... 31 Measuring head scTRACE Gold ...

This manual is also suitable for:

2.946.00202.946.0010

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