780 pH Meter / 781 pH/Ion Meter Manual 8.781.
Metrohm AG CH-9100 Herisau Switzerland Phone +41 71 353 85 85 Fax +41 71 353 89 01 info@metrohm.com www.metrohm.com 780 pH Meter / 781 pH/Ion Meter Program Version 5.780.0020 und 5.781.0020 Manual 8.781.
Teachware Metrohm AG CH-9100 Herisau teachware@metrohm.com This documentation is protected by copyright. All rights reserved. Although all the information given in this documentation has been checked with great care, errors cannot be entirely excluded. Should you notice any mistakes please send us your comments using the address given above. Documentation in additional languages can be found on http://documents.metrohm.com.
Contents Table of contents 1 Introduction.......................................................... 1 1.1 Instrument description ................................................................................. 1 1.2 Parts and controls ........................................................................................ 3 1.3 Information about this Manual ..................................................................... 5 1.3.1 Notation and pictograms ...........................................
Contents 5 Configuration ..................................................... 41 5.1 Report ......................................................................................................... 42 5.2 Printing out measured values .................................................................... 44 5.3 Storing measured values ........................................................................... 47 5.4 Auxiliaries ..........................................................................
Contents 7.2.1 7.2.2 7.2.3 7.2.4 7.2.5 7.2.6 7.2.7 7.2.8 7.2.9 Arrangement of a report .........................................................................98 Report identification ...............................................................................99 Measuring point report ...........................................................................99 Calibration report ..................................................................................
Contents 9.2.1 9.2.2 9.2.3 pH calibration ....................................................................................... 138 Calibration for ion measurements ........................................................ 142 Addition method ................................................................................... 143 9.3 Menu structures ....................................................................................... 144 9.3.1 Instrument configuration ..................................
Contents List of illustrations Fig. 1: 781 pH/Ion Meter connected to 801Magnetic Stirrer .................................................... 1 Fig. 2: Front view of the 780 pH Meter or 781 pH/Ion Meter .................................................... 3 Fig. 3: Rear view of the 780 pH Meter or 781 pH/Ion Meter ..................................................... 4 Fig. 4: Possible arrangements for mounting the base plate .................................................... 8 Fig.
1 Introduction 1 Introduction This Manual provides you with a comprehensive overview of the installation, working principles and operation of the 780 pH Meter and 781 pH/Ion Meter. As these two instruments are identical as far as the three measuring modes of the 780 pH Meter are concerned (pH, temperature and potential) and their operation in these modes is also identical, the Manuals for both have been incorporated in a single document.
1.1 Instrument description tomatic pH electrode test. Up to 100 values can be stored in the memory together with the most important additional data; these can be viewed and outputted as a report. All the parameter settings for a measuring mode can be permanently stored as a method. All stored information (measured values, configuration, parameters, etc.) can be transmitted via the RS 232 interface to a printer or computer for output as a report.
1 Introduction 1.2 Parts and controls Fig.
1.2 Parts and controls Fig.
1 Introduction 1.3 Information about this Manual Please study this Manual carefully before you start to use the instrument. The Manual contains information and warnings that must be observed by the user in order to guarantee the safe use of the instrument. 1.3.
1.4 Safety information 1.4 Safety information Warning! This instrument should only be used in accordance with the information given in this Manual. 1.4.1 Electrical safety Please observe the following guidelines: • • Only qualified Metrohm technicians should carry out service work on electronic components. Do not open the pH/Ion Meter housing. This could destroy the pH/Ion Meter. Inside the housing there are no components that the user can service or exchange.
2 Installation 2 Installation 2.1 2.1.1 Instrument setup Packaging The 780/781 pH/Ion Meter and its specially packed accessories are supplied in very protective special packaging made of shock absorbing polypropylene foam. Please store this packaging in a safe place; it is the only way in which the safe transport of the instrument can be guaranteed. Should you wish to dispose of it please consider suitable disposal or recycling processes. 2.1.
2.2 Connecting the accessories 2.2 Connecting the accessories Both the stand for attaching the stirrer, clamping ring and electrode holder as well as the pH/Ion Meter itself can be mounted on the supplied stand base. You can chose between the arrangements shown in Fig. 4 to suit your own particular working preference. Fig.
2 Installation 2.3 Connecting optional devices Devices which are to be remotely controlled from the pH/Ion Meter (e.g. Metrohm stirrers or Dosimat Plus devices) are connected to MSB connection 9. This can be carried out either directly (801 Magnetic Stirrer or 802 Rod Stirrer with 804 Ti-Stand) or via the optionally available 6.2148.010 Remote Box (e.g. Dosimat Plus). 2.3.1 Connecting the 801 Magnetic Stirrer Mount the magnetic stirrer on the support rod before attaching the clamping ring (6.2013.
2.3 Connecting optional devices 2.3.2 Connecting the 802 Rod Stirrer The 802 Rod Stirrer, in combination with the 804 Ti Stand, can also be connected directly to the pH/Ion Meter. This is done by plugging the MSB connection cable of the 804 Ti Stand into MSB connection 9 of the pH/Ion Meter: Fig.
2 Installation 2.3.3 Connecting a Dosimat Plus (only 781) Controlled addition of standard or sample solutions For automatic calibration as well as for the addition of standard or samples in the Conc mode with the 781 pH/Ion Meter the Metrohm 865 and 876 Dosimat Plus devices can be connected via the separately available 6.2148.010 Remote Box. Control is carried out via the 6.2141.350 cable: Fig. 9: 781 pH/Ion Meter – Dosimat Plus If a Dosimat Plus is used then a stirrer is normally also required.
2.3 Connecting optional devices 2.3.4 Connecting a sample changer For simple automated measurement of several samples and standards with the pH/Ion Meter the Metrohm Compact Sample Changer 869 can be connected. Communication takes place via the 6.2148.010 Remote Box, i.e. the measurements are triggered by the sample changer and their completion is also transmitted by the pH/Ion Meter via the remote connection.
2 Installation 2.3.5 Connecting a printer A printer with a serial or parallel interface can be connected to the RS232 interface for printing out reports. The connection of the 40-character Custom DP40-S4N printer (Metrohm ordering number: 2.140.0200) with the serial 6.2134.110 Cable is described as an example: Fig. 11: 780 pH Meter / 781 pH/Ion Meter – Printer The transmission parameters for the pH/Ion Meter and the printer must be the same.
2.3 Connecting optional devices Printer Custom DP40-S4N Seiko DPU-414 Citizen iDP562 RS Epson LX300+ HP Desk Jet with serial interface HP Desk Jet with parallel interface 14 Cable 780/781 settings 6.2134.110 Character Set: Baud Rate: Data Bit: Stop Bit: Parity: Handshake: 6.2134.110 Character Set: Baud Rate: Data Bit: Stop Bit: Parity: Handshake: 6.2134.050 Character Set: Baud Rate: Data Bit: Stop Bit: Parity: Handshake: 6.2134.050 As above, but Character Set: 6.2134.
2 Installation 2.3.6 Connecting a computer The report output via the RS232 interface can be made to either a printer or a PC. With the program Metrodata Vesuv 3.0 for Windows it is possible to implement automatic data acquisition and evaluation. This is done by connecting RS232 interface 10 of the pH/Ion Meter using the optionally available 6.2134.040 Cable (9-pin/9-pin) with a free serial COM port on the PC. If only a 25-pin COM port is available then the optionally available 6.2125.
2.4 Connecting the electrodes and sensors 2.4 Connecting the electrodes and sensors On its rear panel the 780/781 pH/Ion Meter has connections for a potentiometric electrode 5, a separate reference electrode 6 and a temperature sensor 8. Connect your electrodes and sensors according to the following diagram to the switched off pH/Ion Meter: Fig.
2 Installation 2.5 Mains connection The pH/Ion Meter has an external power supply (6.2153.000) providing 12V (DC). This is connected to 12V mains connection 12. Mains cable One of the following cables is supplied with the instrument • • • • 6.2154.000 Mains cable 2 Pol (C7) – EU (XVI) 6.2154.010 Mains cable 2 Pol (C7) – US (N1/15) 6.2154.020 Mains cable 2 Pol (C7) – GB (BS89/3) 6.2154.030 Mains cable 2 Pol (C7) – AUS (SAA/2) and is connected to the external power supply.
2.7 Initial configuration 2.7 Initial configuration The pH/Ion Meter is delivered with standard settings for the configuration and method parameters. Many of these can be reset at any time by pressing the key during input (see also Section 4.3). If it should ever be necessary to reset the configuration of the instrument to its original condition then this can be carried out by a re-initialization of the instrument memory (see Section 8.5).
3 Short operating tutorial 3 Short operating tutorial In this section the necessary steps for carrying out a simple pH and ion measurement with calibration are described. The instructions are limited to those steps that are absolutely necessary and will enable you to carry out your first measurements with the pH/Ion Meter directly. The operating principles are described in Section 4.4. 3.1 3.1.
3.1 pH measurement ON/OFF 2 CONFIG 3.1.3 Section 5.4 Section 5.4 Section 5.4 Section 5.
3 Short operating tutorial 4 Poor calibration data • If the calibration data are outside the calibration parameters defined as the limits (see Section 6.2.2) then a corresponding message will be shown: ENTER MODE CAL.DATA 7 • You can still accept the calibration data with , or reject it with . 4 Show calibration data • You can now display the calibration data with .
3.1 pH measurement 3.1.4 pH measurement 1 CONFIG Select printout criterion • If the obtained measured value is to be printed out directly as a measuring point report or transferred to a PC then the required printout criterion must be set (see Section 5.2): CONFIG/print meas.value/print crit.: drift STIRRER 2 2 Start measurement • Immerse the pH electrode in the sample. • Switch on stirrer with .
3 Short operating tutorial 3.2 3.2.1 Determination of an ion concentration (only 781: Conc mode) Requirements Carrying out a calibration followed by the direct potentiometric determination of fluoride is described as an example. As this tutorial is only intended to provide a first introduction to ISE measurement with the 781 pH/Ion Meter, the automatic addition of the standard solutions is omitted in order to limit the number of accessories required.
3.2 Determination of an ion concentration (only 781: Conc mode) 1 2 ON/OFF CONFIG 3.2.3 pH/Ion Meter installation • Set up instrument Section 2.1 • Connect stirrer Section 2.3.1 • Connect electrodes Section 2.4 • Mains connection Section 2.5 Initial configuration • Switch on pH/Ion Meter Section 5.4 • Set dialog language Section 5.4 • Set date/time Section 5.4 • Set temperature sensor Section 5.
3 Short operating tutorial 2 CAL Start calibration with first standard • Immerse electrodes in the standard with the lowest F- concentration • Start calibration with • If no temperature sensor is connected: enter the temperature and exit with • Confirm standard concentration with or – if necessary– correct it • Wait for measurement of the potential 3 ENTER Continue calibration with increasing standard concentrations • When the request 'Change std.
3.2 Determination of an ion concentration (only 781: Conc mode) 5 ENTER MODE CAL.DATA 7 Poor calibration data • If the calibration data lies outside certain limits (slope ≤ 80% or ≥ 105% of the theoretical slope of 59.16 mV (25°C) per ionic charge) or the sign of the slope does not agree with the selected ion type a corresponding message will be shown: • You can still accept the calibration data with , or reject it with .
3 Short operating tutorial 'fc 781 pH/Ion Meter 01104 5.781.0010 date 2004-05-13 09:20:50 Conc ******** run number 1 electr.Id conc.calibration ion type F(-1) temperature 22.7 °C temp.sensor Pt1000 c.dat. 2004-05-12 09:32 std. std. std. std. std. 1 2 3 4 5 variance slope E(0) c(blank) 780/781 pH/Ion Meter, Manual conc/ppm 5.00E-01 2.50E+00 5.00E+00 2.50E+01 5.00E+01 U/mV 139.9 97.0 78.8 37.1 19.2 dconc/% 0.2 0.1 -0.6 -0.2 0.4 0.014 -59.9 mV 120.8 mV 0.
3.2 Determination of an ion concentration (only 781: Conc mode) 3.2.4 Direct measurement of fluoride 10 mL of the sample solution (e.g. 10 g table salt in 100 mL dist. water) is also treated with 10 mL TISAB solution. This should first be diluted 1:1 with dist. water. This produces the calculation parameters which are to be defined (see Section 6.5.4).
3 Short operating tutorial MEAS/ PRINT 3 Print out measured value • With you can start the measuring sequence (controlled stirring) and the output of a measuring point report on a printer or PC. The recording of the measurement and its output depend on the printout criterion 'Drift' and take place only when the current drift condition is fulfilled (see Section 6.2.1): 'mp 781 pH/Ion Meter 01104 5.781.0010 date 2004-05-13 09:45:24 Conc ******** run number 12 electr.id smpl.size 10.
3.
4 Operation 4 Operation 4.1 The keypad • Universal functions • Input of numbers and text • Navigation • Special functions The keys beneath the display can be triggered from the measured value display irrespective of the mode. Most of the keys on the right-hand side have two functions: The numbers to be entered and the navigation functions are shown in the center of the keys; the additional functions at their upper margin.
4.2 Operating concept 4.2 Operating concept The pH/Ion Meter provides two types of display: 1. The measured value display. This is the normal instrument display. 2. The menu display This is used for editing various settings. In the directly measuring working modes the current measured value is shown together with the date and time in the measured value display. In the Conc mode the method name and the type of ion selected are also shown.
4 Operation 4.3 All key functions at a glance The functions of all the keys are described below both for the measured value display and the menu display: Key ON/OFF Measured value display (normal operation) Menu display (editing) On/Off switch On/Off switch • The key switches the instrument on and off • The key switches the instrument off at any time. • This applies even if the lamp of the LCD display is switched off! (see Section 5.
4.3 All key functions at a glance Key Measured value display (normal operation) Menu display (editing) Section 5.2), the key prints out the measured value as a measuring point report. MODE QUIT CAL.DATA 7 Operating mode selection Cancels sequence • In the pH, T and U modes (780 pH Meter) and the pH, T, U and Conc modes (781 pH/Ion Meter) the key changes the mode. • With the key working sequences are terminated without direct transfer of the data.
4 Operation Key Measured value display (normal operation) Menu display (editing) • Direct selection of the short result report after . STORE 5 Stores measured value Enters the number '5' • In the pH, T, U and Conc(direct) modes the key triggers a measuring sequence and stores the measured values in the memory in a similar manner to . • The storage criterion must have been previously defined under CONFIG /Store meas. value.
4.3 All key functions at a glance Key ABC . Measured value display (normal operation) Menu display (editing) Enters a decimal point '.' • The <.> key enters a decimal point in the input field. Exception: open text editor • If the key is first pressed in an input field where text input is possible then a text input box for editing the text will be opened. -/exp Enters a minus sign '-' • If you start a numerical input with then the numerical value to be entered will receive a minus sign.
4 Operation CONTRAST+ and CONTRAST - Alters display contrast Controls the menu bar • The contrast of the LCD display can be altered with the and keys during the measured values display. • In each menu display the <> and <> keys can be used to move the selection bar up and down by one line. • This setting is retained after the instrument has been switched off and on. The default value is only reset after the memory has been initialized.
4.4 Operating principles 4.4 4.4.1 Operating principles Configuration and method parameters Instrument configuration and method parameters are each contained in menus with a tree structure. These menu structures are shown in the Annex in Section 9.3. The instrument configuration of the pH/Ion Meter is described in the CONFIG menu. This contains the basic settings that apply for all the selected working modes and methods. The method parameters are stored under PARAMETERS.
4 Operation Values outside the valid range of limits for the particular entry will not be accepted by the instrument. This is indicated by the invalid entry blinking. You can now either enter a new value or retain the original value by exiting with . Special entries exist for some numerical entries; these cannot be seen directly and cannot be edited (e.g. 'OFF' for the measuring parameter Drift). These can be shown with and confirmed with . Text entries 4.4.
4.
5 Configuration 5 Configuration CONFIG With the key you can access the configuration menu. This contains all the instrument settings for the pH/Ion Meter. These are independent of both the mode and the method. This means that they cannot be stored separately like the method parameters (see Section 6). They continue to exist until they are edited or the permanent memory containing the instrument configuration is re-initialized (see Section 8.5).
5.1 Report 5.1 Report REPORT 9 CONFIG ├ report │ ├ id1 : ├ id2 ├ report id ├ instrument id ├ date & time ├ method ├ electrode id ├ signature └ line feed In the configuration menu report you can define the output format of the report header. This describes the first lines of a measuring point report (see also Section 7.2.3) and can be either placed in front of each measured value to be printed out or before a series of measured values (see following section).
5 Configuration An additional way of assigning report printouts to a particular instrument is by using an individual instrument name under CONFIG/auxiliaries/device label (see Section 5.4). This will then be printed out automatically in a separate line in the report header after the instrument Id. date & time: ON, OFF This setting defines whether the date and time of the report printout are to be printed.
5.2 Printing out measured values 5.2 Printing out measured values CONFIG MEAS/ PRINT : ├ print meas.value : └ print crit ┬ │ │ ├ │ │ │ │ ├ │ │ ├ │ │ │ └ immediate time drift plot OFF ┬ ├ └ ┬ ├ ├ ├ └ ┬ ├ └ ┬ ├ ├ └ date & time report header calibration report date & time report header calibration report time interval stop time date & time report header calibration report time interval time scale time scale label stop time In the configuration menu print meas.
5 Configuration Normally each measured value is accompanied by the report header for documentation purposes. The exact contents of the report header are defined under CONFIG/Report (see above). With a larger series of manually triggered measurements it may be advisable to print out the report header only once with the first measured value. In this case all the measurements should be made under the same conditions.
5.2 Printing out measured values print crit.: drift If this print criterion is used then a measured value will only be documented when the drift condition defined under PARAMETERS/measuring parameters/drift has been fulfilled. date & time: report header: calibration report: ON, OFF once, always, OFF ON, OFF These settings correspond to those of the print criterion 'immediate' (see above). print crit.: plot The directly recorded values can be outputted graphically as a measured value/ time plot.
5 Configuration 5.3 Storing measured values STORE 5 CONFIG : ├ store meas. value : └ store crit ┬ immediate, drift, OFF └ time ┬ time interval └ stop time In the direct measuring modes pH, T, U and Conc(direct) you can use to store up to 100 measured values with additional information in the instrument memory (see Section 7.3). The functions of the settings to be defined under CONFIG/store meas. value correspond to those made under CONFIG/print meas.
5.4 Auxiliaries 5.4 Auxiliaries CONFIG : ├ auxiliaries : ├ run number ├ last digit ├ dialog ├ display ├ LCD off after ├ date ├ time ├ time zone ├ temp.sensor ├ temp.unit ├ device label ├ beep └ program Various basic settings for the configuration of the pH/Ion Meter are made in this submenu. run number 0,1,2,3...999, OFF The run number is included in the report. It is increased by one after each measuring process.
5 Configuration LCD off after 1,2...999 min, OFF The display of the pH/Ion Meter has an illuminated background. In order to increase the working life of the lamp you can switch off the display automatically when the instrument has not been used for a certain time. Please note that, if the lamp is switched off and on too frequently then its working life will also be reduced. This means that times of about 30 min can be recommended.
5.4 Auxiliaries temp.unit: C, F The pH/Ion Meter can work with temperature information in both °C and °F units. Please note that, when changing this setting, the default value of the measuring parameter drift in the T mode has the unit °C and, if necessary, must be converted as follows: TF = 32 + 1.8 ·TC or TC = (TF – 32)/1.
5 Configuration 5.5 Monitoring CONFIG : ├ monitoring : ├ validation ├ service └ system test report The 780/781 pH/Ion Meter can inform you automatically about reoccurring quality monitoring tasks. validation: ON, OFF time interval time counter 1...365...9999 d 0 d If this option is active then you can enter a time interval in days and, when it has elapsed, the instrument will request you to carry out a validation process.
5.6 Peripheral units system test report: ON, OFF When it is switched on the 780/781 pH/Ion Meter automatically carries out a system diagnosis. The result can be outputted as a system test report (see Section 8.4.1). 5.6 Peripheral units CONFIG : ├ peripheral units : ├ character set ├ Dosimat ├ stirrer ├ keyboard └ barcode Various peripheral units can be connected to the 780/781 pH/Ion Meter. The corresponding configurations must be carried out here.
5 Configuration strument is switched on. In such a case remove the connected keyboard and switch on the instrument again.
5.7 RS232 settings barcode: input, id1, id2 For data input you can also use a barcode reader which provides a PS/2 connection. Older barcode reader may possibly have a too-high power consumption, which could result in the cancellation of the system test when the instrument is switched on. In such a case remove the connected keyboard and switch on the instrument again. 5.
6 Methods / Parameters 6 Methods / Parameters The exact measuring method of the pH/Ion Meter is described by method parameters which, like the instrument configuration, are arranged in a tree structure in the menu display. The complete tree is shown in the Annex (see Section 9.3) to provide a better overview. The parameters are set in a similar way to the instrument configuration. In contrast, however, the administration of the method parameters is mode-specific.
6.2 pH measurement (pH mode) 6.2 6.2.1 pH measurement (pH mode) Measuring parameters PARAMETER pH ├ measuring parameters : ├ electr.id ├ drift pH ├ temperature* ├ method ├ delta measurement └ stirrer (* only appears if no temperature sensor is connected) The measuring parameters describe the settings which are of direct importance for the measurement. electr.id: 12 ASCII characters You can assign any name you like to the connected pH electrode.
6 Methods / Parameters Please note that the drift condition defined here and the temperature parameter described below do not apply to the calibration and, if necessary, must be set separately under the calibration parameters. temperature -999.9...25.0...999.9 °C This menu item only appears when no temperature sensor is connected. In this case you can enter the temperature of the sample solution here.
6.2 pH measurement (pH mode) The prestir and poststir pauses represent waiting periods in which stirring does not take place. The measurement itself only starts when the complete stirring sequence has ended. Please note that this parameter is binding for the report output and for storing a measured value. Therefore when you start a measurement with the stirrer will be switched on and off accordingly. This is why you should preferably carry out drift-controlled measurements (see Section 5.
6 Methods / Parameters report: OFF, short, full After the calibration it is possible to output the calibration data automatically in the form of a report. You should chose between the 'short' version which contains all the relevant data and the 'full' version which additionally shows the calibration curves in the form of a graph (see Section 7.2.4). Such a report can also be exported at a later date with the calibration data of each stored electrode Id. cal. interval OFF, 1...
6.2 pH measurement (pH mode) Metrohm buffers T [°C] pH 4.00 pH 7.00 pH 9.00 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 3.99 3.99 3.99 3.99 3.99 4.00 4.00 4.01 4.02 4.03 4.04 4.06 4.07 4.09 4.11 4.13 4.15 4.18 4.20 4.23 7.11 7.08 7.06 7.04 7.02 7.00 6.99 6.98 6.98 6.97 6.97 6.97 6.97 6.98 6.98 6.99 7.00 7.00 7.01 7.02 9.27 9.18 9.13 9.08 9.04 9.00 8.96 8.93 8.90 8.87 8.84 8.81 8.79 8.76 8.74 8.73 8.71 8.70 8.68 8.67 The other stored buffer tables are described in Section 9.4.
6 Methods / Parameters buffer type: mixed A further way of using the stored buffer table is to combine a maximum of five different buffer types to form a new series. You can make your selection from all the stored buffers described in Section 9.4. A general rule is that you can only calibrate in defined temperature ranges, as otherwise the error message: buffer not defined appears.
6.2 pH measurement (pH mode) 6.2.3 Limits pH PARAMETER pH : ├ limits pH : └ state In the direct measuring modes the pH/Ion Meter has a limits function which allows the control of the parameter to be monitored. The control signals are transmitted via the MSB connection to the optional remote interface (6.2148.010) (see Section 9.5). Out of limits conditions are also shown on the display and documented in the report. state: u.limit u.hyst. l.limit l.hyst. pH pH pH pH ON, OFF -19.999...14.000...19.
6 Methods / Parameters 6.2.5 Plot parameters PARAMETER pH : ├ plot parameters : ├ left mar. pH ├ right mar. pH ├ left marg.T └ right marg.T The two directly recorded measuring quantities pH and temperature can be printed out as a function of time in a plot. Under CONFIG/print meas. value the print criterion 'plot' must be selected (see Section 5.2). The scales of the measured values axes are determined by the following limits. left mar. pH right mar. pH left marg.T right marg.T TIP ! 6.2.6 -19.9...0.
6.2 pH measurement (pH mode) 6.2.7 Electrode test PARAMETER pH : └ electrode test ├ electrode type ├ temperature └ report The pH/Ion Meter can carry out a pH electrode test, which permits the quality of the electrode used to be evaluated. A detailed description of the electrode test is given in Section 8.6. electrode type: standard, gel, non-aq., own Various types of pH electrodes have different evaluation criteria.
6 Methods / Parameters 6.3 6.3.1 Temperature measurement (T mode) Measuring parameters PARAMETER T ├ measuring parameters : ├ electr.id ├ drift ├ method ├ delta measurement └ stirrer The measuring parameters describe the settings of direct importance for the measurement. electr.id 12 ASCII characters You can assign any name you want to the connected temperature sensor. This sensor Id is then contained in the report header for measured values. drift 0.5...1.0...999.
6.3 Temperature measurement (T mode) This reference value is subtracted from the measured value itself. The modified measured value is shown together with this value and is taken into consideration, for example, in checking the limit values (see PARAMETER T/limits T). The reference value is not included in the report. However, should you still want to document it then you should also produce a parameter report (see Section 7.2.7).
6 Methods / Parameters The exact way in which the limits function works is described in Section 7.4 independent of the mode. You should only activate this limits function for the temperature if a temperature sensor is connected, as otherwise the following message will appear limit error 6.3.3 Plot parameters PARAMETER T : ├ plot parameters : ├ left mar. └ right mar. The measured temperature can be printed out as a function of time in a plot. Under CONFIG/print meas.
6.4 Potential measurement (U mode) 6.4 6.4.1 Potential measurement (U mode) Measuring parameters PARAMETER U ├ measuring parameters : ├ electr.id ├ drift ├ method ├ delta measurement └ stirrer The measuring parameters describe the settings which are of direct importance for the measurement. electr.id 12 ASCII characters You can assign any name you like to the connected pH electrode. The electrode Id will then be included in the report header for the output of measured values. drift 0.1...1.0...999.
6 Methods / Parameters delta measurement: ON, OFF The delta measurement permits the display of the measured value relative to a freely selectable constant reference value: reference -2200.0...0.0... 2200.0 mV This reference value is subtracted from the measured value itself. The modified measured value is shown together with this value and is taken into consideration, for example, in checking the limit values (see PARAMETER U/limits U). The reference value is not included in the report.
6.4 Potential measurement (U mode) state: u.limit u.hyst. l.limit l.hyst. ON, OFF -2200.0...1000.0...2200.0 mV -2200.0...2.0...2200.0 mV -2200.0...-1000.0...2200.0 mV -2200.0...2.0...2200.0 mV The exact way in which the limits function works is described in Section 7.4 independent of the mode. 6.4.3 Plot parameters PARAMETER U : ├ plot parameters : ├ left mar. └ right mar. The measured potential can be printed out as a function of time in a plot. Under CONFIG/print meas.
6 Methods / Parameters 6.5 6.5.1 Direct ion measurement (781 only: Conc mode) Type of measurement PARAMETER Conc ├ meas.type : The type of measurement describes the analytical principle of ion measurement. meas.type: direct, std.add, smpl.add In general a differentiation is made between direct measurement and the standard or sample addition methods. The selection of the method parameters depends on the measurement type which has been chosen.
6.5 Direct ion measurement (781 only: Conc mode) conc.unit: mol/L, %, ppm, g/L, mg/L, µg/L, mEq/L, own The analyte concentration unit is defined here. It is used in both the calibration and the measurement itself. Under 'own' you can also define your own unit with 5 ASCII characters: unit 5 ASCII characters Please note that this unit does not form part of the measured value itself but is only a supplement.
6 Methods / Parameters measured value is to be stored or documented by printing a report (see print criterion and storage criterion in Section 5.2 and Section 5.3). Please note that for a drift-controlled measured value recording this drift parameter must not be set to 'OFF', as otherwise no result will be exported. If this drift condition is not fulfilled then this is indicated by two constantly blinking triangles in the display.
6.5 Direct ion measurement (781 only: Conc mode) rer has been connected and the settings made under CONFIG/peripheral units then the stirring rate can also be selected: stirring rate 1...5...15 If you want your measurement to be made without stirring but still want to stir the solution before the measurement then you should select the control setting. In this way you can trigger a stirring sequence before the start of each measurement with : prestir pause stir time poststir pause 0...
6 Methods / Parameters Measured value(new ) = factor ⋅ V total ⋅ Measured value(old) smpl.size Please note that the unit of the measured value is not altered in this calculation. The Meas. value(new) will therefore always have the same unit as Meas. value (old), i.e. the unit which has been set under PARAMETER CONC/ion parameters and with which the calibration has been carried out. For example, if you use the smpl.size unit: mL, then the quotient Vtotal/smpl.
6.5 Direct ion measurement (781 only: Conc mode) drift: 0.1...0.5...9.9 mV/min Just like the ion measurement, the calibration is also drift-controlled. However, this drift-control cannot be switched off. report: OFF, short, full After the calibration you can automatically output the result in the form of report. You can choose between the 'short' version containing all the relevant data and the 'full' version, which also shows the measuring curves as a graph (see Section 7.2.4).
6 Methods / Parameters configuration see Section 2.3.3, pH/Ion Meter configuration see Section 5.6). min.conc 1.0E-30...0.1...1.0E+30 max.conc. 1.0E-30...1.0...1.0E+30 The standard concentrations to be calculated lie within the range of these minimum and maximum concentrations. Depending on the required number of standards (see above), the pH/Ion Meter will calculate the other concentrations. The expected resulting potential difference between all the standards remains constant. V init 0.001...100.0...
6.5 Direct ion measurement (781 only: Conc mode) interface (6.2148.010) (see Section 9.5). Out of limits conditions are also shown on the display and documented in the report. state: u.limit u.hyst. l.limit l.hyst. ON, OFF -1.00E+30...1.00E+30 -1.00E+30...2.00...1.00E+30 -1.00E+30...0.00...1.00E+30 -1.00E+30...2.00...1.00E+30 The exact way in which the limits function works is described in Section 7.4 independent of the mode. 6.5.
6 Methods / Parameters left mar. right mar. left marg.T right marg.T TIP ! 6.5.9 -1.0E+30...0.0...1.00E+30 -1.0E+30...1.00E+30 -999...20...999 °C -999...30...999 °C The value for the right-hand limit of a plot must not necessarily be the larger one. By exchanging the limits the plot of the particular quantity can be mirrored. Preselections (applies only to measurement type: direct) PARAMETER Conc : └ preselections ├ req.ident └ req.smpl.size req.ident.
6.6 Standard and sample addition (781 only: Conc mode) 6.6 Standard and sample addition (781 only: Conc mode) In the ion measurement Conc mode a differentiation is made between direct measurement and the standard or sample addition and subtraction methods. All the method parameters for direct concentration determination are described in Section 6.5.
6 Methods / Parameters type: add, sub In general – and also in this Manual – when dealing with standard and sample addition techniques it is addition which is described. It is also possible to carry out a standard or sample subtraction, for example by precipitation reactions. The appropriate type is set here. conc.std. 1.0E-30...1.0...1.
6.6 Standard and sample addition (781 only: Conc mode) TIP ! It is possible to alter this parameter during an addition run. For example, before confirming the volume increment you can add the solution during the run until a certain potential difference is shown on the display. Then confirm the volume to be added; the corresponding potential will be measured after each addition. This can be a great help, for example when checking the suitability of a standard for this method. stop V 0...99.99...9999.
6 Methods / Parameters auto dos increment 1...n 1.0E-30...0.1...999.9 mL The particular volume increment must be entered for each addition of the standard or sample solution. auto delta U 1...10...999 mV Under auto the required potential difference must be entered. Please note that the Dosimat Plus must be properly prepared before the start of an addition run (cylinder freshly filled, air bubbles removed, etc.).
6.
7 Various functions 7 Various functions This section describes various functions of the pH/Ion Meter which cannot be assigned to individual modes. 7.1 Calibration and addition/subtraction data The current pH calibration data can be called up at any time with the key. For the 781 pH/Ion Meter the same applies to the concentration calibration () and the addition or subtraction data () in the Conc mode.
7.1 Calibration and addition/subtraction data method The calibration parameters set under PARAMETER pH/calibration parameters form part of the method parameters. The corresponding method name will be shown here if the calibration data has been obtained with this method and the resulting quantities slope and pH(0) have not been altered since. If no method name has been issued before the calibration (see Section 6.1) then '********' will appear here.
7 Various functions variance If at least 3 calibration buffers have been used then the calibration function will be calculated as a compensation curve according to the principle of the smallest mean-square error (linear regression). The resulting variance will be given here. A more detailed explanation of these calculations is given in Section 9.2.1. Each subsequent manual alteration of the calibration data pH(0) and slope will be documented by the entry 'manual' against these parameters.
7.1 Calibration and addition/subtraction data reset cal With this option you can reject all the calibration data of an electrode Id. They are then in the same state as before the first calibration (slope = 100%, pH(0) = 7). Although the electrode Id is retained, it cannot be selected under pH/measuring parameters/electr.id until it has been calibrated again. PARAMETER b1, b2...bn For each calibration buffer the pH value used and the measured potential are given.
7 Various functions 7.1.2 Conc calibration data (781 pH/Ion Meter only) CAL.DATA 7 CAL.DATA ├ ion type ├ electr.Id ├ method ├ slope ├ E(0) ├ c(blank) ├ temperature ├ temp.sensor ├ c.dat. ├ cal.interval ├ variance ├ no.of standards ├ cal.table ├ st1 ├ st2 : ├ stn └ curve ion type The analyte ion which has been defined during the calibration under PARAMETER Conc/ion parameters is shown here. As with the following electrode Id, the current calibration data changes as the ion parameter changes. electr.
7.1 Calibration and addition/subtraction data and from the calibration data report. The calibration date and time will be updated and the temperature information and the calibration table (see below) will be removed. In addition this action will be documented by the entry 'manual' under CAL.DATA/variance. E(0) This is the second characteristic quantity of the calibration function. E(0) is the potential at log(c) = 0, i.e. the U-axis intercept of the calibration function in the U/log c plot.
7 Various functions variance If at least 4 standards have been measured then the calibration function will be calculated iteratively according to the principle of the smallest mean-square error. The resulting variance will be given here. However, if the value calculated for c(blank) is sufficiently small then the variance will be given after only three standards have been measured. A more detailed explanation of these calculations is given in Section 9.2.2.
7.1 Calibration and addition/subtraction data Although the electrode Id is retained, it cannot be selected under PARAMETER Conc/measuring parameters/electr.id until it has been calibrated again. st1, st2...stn For each calibration standard the concentration and the measured potential are shown. A standard which has been deleted by cal.table: delete n is shown here by 'deleted'. curve < –> > If at least 2 calibration standards have been used then the calibration curve will be shown as a graph here.
7 Various functions 7.1.3 Addition/Subtraction data (781 pH/Ion Meter only) ADD.DATA 4 ADD.DATA ├ ion type ├ meas.type ├ electr.id ├ variance ├ slope ├ E(0) ├ c Ion ├ date ├ method ├ temperature ├ temp.sensor ├ V total ├ conc.std ├ initial voltage ├ factor ├ smpl.size ├ add1 ├ add2 : ├ addn └ curve The data of the last standard or sample addition and subtraction to have been carried out can be called up with provided that the measurement type has been set to 'std.add' or 'smpl.
7.1 Calibration and addition/subtraction data variance With at least 3 additions the compensation curve for U/log(c) will be calculated according the principle of the smallest mean-square error. The resulting variance will be given here. A more detailed explanation of these calculations is given in Section 9.2.2 and Section 9.2.3. slope The slope of the calibration function obtained during the addition will be shown here in mV.
7 Various functions V total This is the initial volume of the solution as defined under PARAMETER Conc/calculation parameters (see Section 6.5.4). conc.std The concentration of the standard used is shown here as defined under PARAMETER Conc/standard addition. initial voltage The initial potential measured in the solution is shown here. factor smpl.size These are further calculation parameters defined under PARAMETER Conc/calculation parameters and used to calculate the final result (see Section 6.5.4).
7.2 Reports 7.2 Reports A pH/Ion Meter report is produced by transmitting data to a printer or PC via the RS232 interface. In this way you can document e.g. measuring results, calibration data, method parameters or the configuration of the instrument in written form. A requirement for a properly functioning report output is the input of the receiving instrument (see Section 5.6) and the correct setting of the RS232 transmission parameters (see Section 5.7).
7 Various functions The following table shows the availability of all reports in the various modes together with the direct selection keys. pH T U Conc Direct key user memory - calib short - - calib full - - - config param result short - - - result full - - - - el.test - - -
7.2 Reports 7.2.1 Arrangement of a report The first lines of a report provide a general description. This report header is configured under CONFIG/Report (see Section 5.1): Report Id: 'mp Instrument Id: 781 pH/Ion Meter 01104 Date, Time: date 2004-05-28 17:00:56 5.781.0020 ...
7 Various functions 7.2.2 Report identification The report identification, known here as Report Id, is an abbreviation describing the type of report and is primarily important for the remote control of the pH/Ion Meter via the RS232 interface. Computer programs such as Metrohm Vesuv© 3.0 for WindowsTM can identify the produced report by this identification and use it for further evaluation. The following report Ids exist for the 780 pH Meter and 781 pH/Ion Meter: Report Id 7.2.
7.2 Reports If a whole series of measured values is to be documented then this is done by selecting under CONFIG/Print meas. values the option Report header: once. In this way the report header will be printed out once with the first measured value. Each further time that the key is pressed a further measured value will be printed out: #2 #3 #4 #5 pH = 8.185 2004-05-28 pH = 8.187 2004-05-28 pH = 8.188 2004-05-28 pH = 8.189 2004-05-28 21.2 °C 17:01:56 21.2 °C 17:02:56 21.2 °C 17:03:56 21.
7 Various functions 7.2.4 Calibration report REPORT 9 CAL.DATA + 7 In the pH and Conc(direct) modes a calibration report can be produced after a calibration has been carried out. Under PARAMETER/calibration parameters/report you can define whether this report is to be produced automatically after the measurement. You can also choose between a short version containing all the important data and a long version which additionally contains a plot of the calibration function.
7.2 Reports 7.2.5 Result report (781 pH/Ion Meter only) REPORT 9 ADD.DATA + 4 In the Conc mode for standard or sample addition the results can be produced as a result report. Under PARAMETER Conc/Standard addition/Report you can define whether this result is to be produced automatically after the end of the measurement.
7 Various functions 7.2.6 Configuration report A configuration report (CONFIG) could look like this: REPORT 9 + CONFIG 780/781 pH/Ion Meter, Manual 'co 781 pH/Ion Meter 01104 5.781.0020 date 2004-06-03 10:03:55 CONFIG >report id1 id2 report id: ON instrument id: ON date & time: ON method: ON electrode id: ON signature: OFF line feed 3 >print meas.value print crit: immediate date & time: OFF report header: always calibration report: OFF >store meas.
7.2 Reports The settings shown for the instrument configuration correspond to the standard settings in the normal operating condition of the pH/Ion Meter after the configuration memory has been initialized (see Section 8.5) followed by conversion to English as the dialog language. 7.2.
7 Various functions 7.2.8 Measured values memory report REPORT 9 RECALL + 6 In the direct types of measurement you can store up to 100 measured values with (see Section 7.3). If you want to print out all the stored data then you can produce a measured values stored report: 'mw 781 pH/Ion Meter date 2004-06-03 01104 13:55:20 5.781.0020 #1 pH 7.254 temp. (Pt1000) 20.1 °C id1 smpl. 1-1 date 2004-06-03 13:54:10 method pH Demo #2 pH 6.923 temp. (Pt1000) 20.1 °C id1 smpl.
7.2 Reports 7.2.9 User method report METHODS REPORT 9 + 3 Method and calibration data occupy memory space in the pH/Ion Meter. The user method report gives an overview of the memory occupancy: 'um 781 pH/Ion Meter 01104 date 2004-06-03 13:58:49 user memory >methods pH pH-Demo Conc F(-1) F-Determ >caldata pH pH 1.1 Conc F(-1) F-Sens remaining bytes -------------- 5.781.0020 82 64 130 146 4578 The mode, method name and the occupied memory is given in bytes for each of the methods.
7 Various functions 7.3 Measured values memory In the direct measuring modes pH, T, U, and Conc(direct) the pH/Ion Meter can store up to 100 measured values with additional information. Depending on the storage criterion you can store the measured values immediately, at fixed time intervals or drift-controlled. The appropriate instrument settings are made under CONFIG/Store meas. value and their functions correspond to the settings for printing the measured values.
7.3 Measured values memory 7.3.3 Show measured values RECALL 6 With the menu for displaying or deleting stored measured values is called up: measured value memory >show measured values del mv store: no Select the item Show measured values in order to access the corresponding display. The last measured value to have been stored with the highest number will always be shown first: Measured value no. No.
7 Various functions 7.4 Limit monitoring In all the direct measuring modes pH, T, U, Conc(direct) it is possible to monitor the current measured value with respect to certain upper and lower limits. In the modes pH and Conc(direct) the temperature can also be monitored. Under PARAMETERS/limits you can activate limits monitoring. Depending on the measuring mode you may be able to monitor the limits of a secondary measured value in addition to the primary measured value.
7.4 Limit monitoring 7.4.2 How it functions The exact way in which limit monitoring functions and the effect on the remote outputs are shown in the following diagram. measured value u. limit u. hysteresis l. hysteresis l. limit signal output time aktive u. limit inaktive aktive l. limit inaktive Fig. 13: Remote outputs in limit monitoring The lower and upper limits and the associated hysteresis are the characteristic quantities for limit monitoring.
7 Various functions 7.5 Setup Certain settings of the pH/Ion Meter can be found in the Setup menu. This menu cannot be accessed from the normal instrument display, as alterations to these settings have a great influence on the functions of the pH/Ion Meter. The Setup menu is called up immediately after the instrument has been switched on by pressing down and holding down the key. setup ├ lock ├ input assign ├ graphics └ instr.
7.5 Setup 7.5.2 Input assignment setup : ├ input assign : ├ Mode pH 1 ├ Mode T 2 ├ Mode U 3 ├ Start pH cal. 5 ├ Start el.test 6 ├ Mode conc. 8 ├ Start conc.cal. 9 └ 15 The pH/Ion Meter can communicate with other Metrohm instruments via the optionally available Remote box (see Section 9.5). In special cases it may be a good idea to alter the assignments of the actions to be triggered to the signal impulses on input lines Input 1 to Input 4 (see Section 9.5.2).
8 Troubleshooting – Messages – Maintenance 8 Troubleshooting – Messages – Maintenance 8.1 Troubleshooting If problems occur during pH or ISE measurement then these can have various causes: 1. Application Difficult sample matrices or interferences can prevent reliable measurements (e.g. insufficient ionic strength, presence of interfering ions in ISE measurements, etc.).
8.
8 Troubleshooting – Messages – Maintenance Problem Possible cause Remedy With standard addition 'auto' the potential step 'delta U' is not reached Streaming potential of the measuring or reference electrode causes potential difference between addition in stirred and measurement in unstirred solution • • • • System test message: system error #X Instrument fault • Note error number and inform Metrohm Service 8.
8.2 Messages Message Situation Cause Remedy XXX bytes missing Method storing XXX bytes are missing for saving a method Press to delete old methods V add too large Conc calibration, Standard volume to be standard addition added is larger than buret volume • Use larger buret • Reduce start volume • Increase standard concentration V add too small Conc calibration, Standard volume to be standard addition added is too small • Check parameters (see Section 6.5.5 or 6.6.
8 Troubleshooting – Messages – Maintenance Message limit error Situation Cause Direct measurement, all modes Set limit for primary or sec- see Section 7.4 ondary measured value exceeded cal. interval pH and Conc expired modes cal.data out of pH calibration limits Conc calibration Set calibration interval has expired Recalibrate electrode (see Section 6.2.2 and 6.5.
8.2 Messages Message Situation Cause Remedy buffers unsuitable Electrode test Electrode test has been started with a set of buffers that does not contain all the necessary buffers • Change buffers • Check selected buffer type in the calibration parameters (see Section 8.6.1) change buffer pH calibration Instrument is waiting for new buffer buffer alloc. impossible? pH calibration 1. Change buffer 2. Press • Buffer not recognized or 1. Replace buffer not defined (buffer type 2.
8 Troubleshooting – Messages – Maintenance Message Situation Cause Remedy RS error 45 Report output RS transmitter error: The receiver buffer of the pH Meter contains an incomplete character string (line feed missing); this has blocked pH Meter transmission • Press • Send line feed stirrer not found Various situations An attempt has been made 1. Press to control an 8xx series 2. Switch off instrument stirrer which is not con3.
8.3 QM support 8.3 QM support Metrohm AG can support you in your quality management (QM) measures: Literature Brochures in the series "Quality management with Metrohm" provide an overview of the topics of quality assurance and validation, help with the documentation of your validation activities and explain the quality management system at Metrohm AG, Herisau. You can request them under www.metrohm.com or from your local Metrohm agency.
8 Troubleshooting – Messages – Maintenance Service contract Under a separate service contract you can receive particular service performances within the framework of preventative maintenance. The documented specifications of the instrument will be checking by the service technician responsible at regular intervals; the technician will document the results and suggest any measures which may be necessary.
8.4 Validation 8.4 Validation The checking and maintenance of the pH/Ion Meter can be carried out in 3 steps. This list can be extended by the measures described in Section 8.3. 1. Checking the electronic components when the instrument is switched on. 2. Validation of the whole analytical system by wet chemistry. 3. pH/Ion Meter maintenance by Metrohm Service. 8.4.1 Electronic tests After the pH/Ion Meter has been switched on an electronic system test is carried out automatically.
8 Troubleshooting – Messages – Maintenance 8.4.2 Wet tests Quality assurance standards such as GLP (Good Laboratory Practice) require the regular validation of the analytical instruments. The reproducibility and accuracy of the instruments are checked. Repeating the test at yearly intervals is normally adequate. However, depending upon the requirements, it may be necessary to carry out the test more frequently, e.g. every 3 months or every 6 months.
8.5 Diagnosis 8.5 Diagnosis The pH/Ion Meter is equipped with a diagnosis program. This allows selective checks of the functions of individual assemblies. The diagnosis can be carried out directly after the instrument has been switched on by pressing and holding down the <9> key. Only those tests that you can carry out yourself are described below; the other functions are reserved for Metrohm Service personnel.
8 Troubleshooting – Messages – Maintenance RAM Test This test checks the condition of the instrument memory without altering its contents. A successful test is concluded with the message 'ram test ok'. AD-Converter Test The electronic components of the analog-digital converter are checked. At the end the two messages 'ADC EEPROM Test ok' and 'ADC Int. ok x mS' should appear. Instead of 'x' the message should contain a number between 15.0 and 25.0.
8.6 pH electrode test 8.6 pH electrode test EL.TEST 1 With the pH/Ion Meter you can carry out an automatic pH electrode test which allows the quality of the electrode used to be evaluated. As the result you will obtain various information about the characteristic measuring properties of your pH electrode (slope, response time, drift, streaming potential). The concluding evaluation of the electrode is carried out by checking the results obtained against preset tolerances.
8 Troubleshooting – Messages – Maintenance With a 801 Magnetic Stirrer the test is fully automated. You just have to change the buffers. Set the stirring rate at PARAMETER pH/measuring parameters/stirrer: stirring rate The stirring rate should be set so that the stirring action is powerful but without the formation of air bubbles (avoidance of absorbing CO2).
8.6 pH electrode test EL.TEST 1 1 Start pH electrode test • The electrode test is started from the pH measured value display with . 2 (Enter temperature) • If no temperature sensor is connected then the measuring temperature of the buffers must be entered here. This should be the same for all buffers. 3 Immerse electrode in pH 9 buffer • Immerse the electrode in the pH 9 buffer and immediately press . ENTER • The instrument now counts down from 239 to 0 seconds.
8 Troubleshooting – Messages – Maintenance 8.6.3 Results The following graph shows the potential of the pH electrode as a function of time during the electrode test for a buffer in diagram form: Fig. 14: Diagram showing changes in potential during an electrode test The evaluation of the pH electrode is made according to the following criteria.
8.6 pH electrode test The following table lists the preset tolerances for the three types of electrode: excellent electrode good electrode passing electrode ≤ 2.5 ≤ 2.0 96.5 ≤ s ≤ 101 ≤ 45 ≤ 3.0 ≤ 2.5 96 ≤ s ≤ 102 ≤ 50 ≤ 4.0 ≤ 3.0 95 ≤ s ≤ 103 ≤ 60 -15 ≤ U off ≤ 15 Electrode type: standard Streaming potential dU [mV] Total drift [mV] Slope s [%] Response time [s] Offset potential U off [mV] Electrode type: gel => all (reference-) electrodes filled with Idrolyte Streaming potential dU [mV] ≤ 3.0 ≤ 3.
8 Troubleshooting – Messages – Maintenance 8.6.
8.6 pH electrode test Test criterion Message Measure pH 9: absolute drift in stirred solution > 1 mV/min problem Clean diaphragm and/or regenerate the glass membrane. pH 9: -10 mV < U(unstirred) < 10 mV AND sum of abs. drift values after 1, 2, 3 and 4 min < 12 mV/min short circuit Replace electrode (short circuit or crack in glass membrane). 2 slopes do not meet the conditions for a passing electrode check buffer/ electrode Repeat test using correct buffers.
8 Troubleshooting – Messages – Maintenance Storage • Combined glass electrodes with c(KCl) = 3 mol/L as reference electrolyte should be stored in the Storage solution 6.2323.000 (also contained in the maintenance kit for pH electrodes 6.2325.000). If the electrode is stored in water, then AgCl will precipitate out in the diaphragm! pH glass electrodes filled with another reference electrolyte should be stored in that reference electrolyte. • Separate glass electrodes should be stored in distilled water.
8.
9 Annex 9 Annex In this section you will find the most important technical data of the pH/Ion Meter, a description of evaluation principles, dialog structures, buffer tables, a description of the optional remote box, a list of standard accessories and optional accessories as well as warranty and declarations of conformity. 9.1 Technical data Provided that nothing to the contrary is mentioned, the published values represent the typical data of the 780 pH Meter and the 781 pH/Ion Meter. 9.1.
9.1 Technical data 9.1.3 1 2 Measuring input specifications Measuring range Resolution Measuring accuracy 1) pH –20.000...+20.000 0.001 pH ± 0.003 pH Temperature Pt1000 NTC –150 °C...+250 °C –20 °C...+250 °C 0.1 °C 0.1 °C ± 0.2 °C (Pt1000: –20 °C... +150 °C) Potential –2200 mV...+2200 mV 0.1 mV ± 0.2 mV Concentration (781 only) 1.0 ⋅ e-37... 1.0 ⋅ e37 0.2 % 2) ± 0.4 % 2) ) ±1 digit, without sensor error, under reference conditions ) for single charged Ions 9.1.
9 Annex 9.1.6 Safety specifications Instrument 780/781 9.1.7 9.1.8 9.1.9 Standards fulfilled: - EN/IEC 61010-1 - UL 61010-1 - CSA-C22.2 No.
9.2 Evaluation 9.2 9.2.1 Evaluation pH calibration pH calibration is used to assign the potentials measured at the pH electrode to the corresponding pH values. This relationship is known theoretically and is described by the Nernst equation. For pH measurement it can be simplified to: U = UpH= 0 − UN ⋅ pH T: absolute temperature in K R: ideal gas constant F: Faraday constant R⋅T where UN = ln(10) ⋅ F UpH=0 is the ordinate intercept at pH = 0. Its value depends on the construction of the electrode.
9 Annex trolyte or an unsuitable reference system. The slope can also differ slightly from UN. As these variations describe the condition of the pH electrode and are subject to variation with time this means that, depending on the accuracy required, a regular pH calibration is necessary. This calibration provides a new description of the relationship between the electrode potential and the measured pH value: U/mV 200 pH(0) 7 100 Slope 0 4 Uoff 7 9 pH -100 Fig.
9.2 Evaluation The calculation of the calibration data depends on the number of pH buffers used: 1-Point calibration Slope: The theoretical slope value of 100.0% is used.
9 Annex Notes For a pH calibration at least two or more different buffers should be used; these should cover the intended measuring range (DIN 19268). For example, you can obtain Metrohm buffer solutions for pH 4, 7 and 9 as ready-to-use solutions or concentrates (see Optional Accessories, Section 9.6). A pH electrode is an ion-selective electrode which responds to hydrogen ions (H+) with great selectivity.
9.2 Evaluation 9.2.2 Calibration for ion measurements Just as for pH measurement, ion measurement using an ion-selective electrode (ISE) also requires regular calibration. In contrast to pH measurement, a linear relationship between the measured potential Ui and the logarithm of the required ion concentration ci cannot always be assumed. The influence of the interfering ions which is responsible for this can be described by the Nikolsky equation.
9 Annex 3- and more point calibration With at least 3 calibration solutions the calibration function is determined according to the principle of the smallest mean-square error. The required calibration parameters Slope, E(0) and c(blank) are calculated iteratively. If c(blank) is sufficiently small to have no measurable influence, what means that c(blank) would be smaller than approx. 0.2 % of the smallest measured value, then it is set as zero and not shown.
9.3 Menu structures 9.3 Menu structures The menu structures of the instrument configuration and the method parameters of all operating modes are shown on the following pages. This so-called instrument tree can also be used to control the pH/Ion Meter via the serial interface. It is described in a separate document together with the exact syntax used (780/781 pH/Ion Meter Operation via RS232, No. 8.781.1113). The document is available from your local Metrohm agency. 9.3.
9 Annex CONFIG : ├ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ ├ │ │ │ │ │ ├ │ │ │ │ │ │ └ 780/781 pH/Ion Meter, Manual auxiliaries ├ run number ├ last digit ├ dialog ├ display ├ LCD off after ├ date ├ time ├ time zone ├ temp.sensor ─┬ │ │ ├ ├ ├ └ └ temp.
9.3 Menu structures 9.3.2 Method parameters in the pH mode PARAMETER pH ├ measuring parameters │ ├ electr.id │ ├ drift pH │ ├ temperature │ ├ method │ ├ delta measurement ─ ON ─── reference pH │ └ stirrer ───┬ ON ──── stirring rate │ └ control ┬ stirring rate ├ calibration parameters ├ prestir pause │ ├ temperature ├ stir time │ ├ drift └ poststir pause │ ├ report │ ├ cal.interval │ ├ no.of buffers │ ├ buffer type ───┬ Metrohm, NIST, DIN, ...
9 Annex 9.3.3 Method parameters in the T mode PARAMETER T ├ measuring parameters │ ├ electr.id │ ├ drift │ ├ method │ ├ delta measurement ─ ON ── reference │ └ stirrer ────┬ ON ── stirring rate │ └ control ┬ stirring rate │ ├ prestir pause │ ├ stir time │ └ poststir oause ├ limits T │ └ state ───── ON ──┬ u.limit │ ├ u.hyst. ├ plot parameters ├ l.limit │ ├ left mar. └ l.hyst. │ └ right mar. │ └ 9.3.4 preselections └ req.
9.3 Menu structures 9.3.5 Method parameter in the Conc mode PARAMETER Conc ├ meas.type all meas.types only meas.type: direct 148 │ ├ │ │ │ │ │ ├ │ │ │ │ │ │ │ ├ │ │ │ │ │ ├ │ │ │ │ │ │ │ │ │ │ │ │ ├ │ │ │ │ ├ │ │ ├ │ │ │ │ │ └ ion parameters ├ ion type ────┬ F(-1), I(-1), K(+1), ... │ └ own ┬ ion name │ └ ion charge └ conc.unit ────┬ mol/L, %, ppm, ... └ own ─ unit name measuring parameters ├ electr.
9 Annex only meas.type: std.add and smpl.add 780/781 pH/Ion Meter, Manual : ├ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ └ standard addition / sample addition ├ type ├ conc.std. ├ report └ addition ───┬ manual ┬ no.of additions │ ├ increment 1...n │ └ stop V ├ auto dos ┬ dos.rate │ ├ no.of additions │ ├ V Exchange Unit │ ├ increment 1...n │ └ stop V └ auto ──┬ delta U ├ dos.rate ├ no.of additions ├ V Exchange Units preselections └ stop V ├ req.ident ├ req.smpl.
9.4 Stored buffer series 9.4 Stored buffer series For automatic buffer recognition during pH calibration the temperaturedependent pH values of several common pH buffers are stored in the 780/781 pH/Ion Meter. Apart from the Metrohm buffer solutions other reference and technical buffers are also included in the tables. The following tables provide an overview of the stored pH(T) series.
9 Annex DIN (according to DIN standard 19267, 1978) Temp. (°C) DIN1 DIN3 DIN4 DIN7 DIN9 DIN12 pH 1 pH 3 pH 4 pH 7 pH 9 pH 12 0 1.08 - 4.67 6.89 9.48 - 1) 1) 5 1.08 - 4.66 1.09 3.10 4.66 6.84 9.37 13.37 15 1.091) 3.081) 4.651) 6.821) 9.321) 13.151) 20 1.09 3.07 4.65 6.80 9.27 12.96 25 1.09 3.06 4.65 6.79 9.23 12.75 30 1.10 3.05 4.65 6.78 9.18 12.61 35 1.10 40 1.10 1) 45 1.10 50 1.11 1) 55 1.11 60 1.11 1) 65 1.11 70 1.11 1) 75 1.
9.4 Stored buffer series Mettler Toledo Temp. (°C) Beckmann MT2 MT4 MT7 MT9 MT11 Bec4 Bec7 Bec10 pH 2 pH 4 pH 7 pH 9 pH 11 pH 4 pH 7 pH 10 1) 1) 1) 1) 1) 4.00 7.12 10.32 0 2.03 4.01 7.12 9.52 11.90 5 2.02 4.01 7.09 9.45 11.72 4.00 7.09 10.25 10 2.01 4.00 7.06 9.38 11.54 4.00 7.06 10.18 15 2.00 4.00 7.04 9.32 11.36 4.00 7.04 10.12 20 2.00 4.00 7.02 9.26 11.18 4.00 7.02 10.06 25 2.00 4.01 7.00 9.21 11.00 4.00 7.00 10.01 30 1.99 4.
9 Annex Baker Temp. (°C) Bak4 Bak7 Bak9 Bak10 pH 4.00 pH 7.00 pH 9.00 pH 10.00 0 4.00 7.13 9.23 10.30 5 4.001) 7.091) 9.171) 10.241) 10 4.00 7.05 9.10 10.17 15 4.00 1) 7.03 1) 9.05 1) 10.111) 20 4.00 7.00 9.00 10.05 25 4.001) 6.981) 8.961) 10.00 30 4.01 6.98 8.91 9.96 35 4.021) 6.981) 8.881) 9.931) 40 4.03 6.97 8.84 9.89 45 4.04 1) 6.97 1) 8.81 1) 9.861) 50 4.05 6.96 8.78 9.82 55 4.071) 6.961) 8.761) 9.791) 60 4.08 6.96 8.73 9.
9.4 Stored buffer series Merck Titrisol Temp. (°C) Mer1* Mer2 Mer3* Mer4 Mer4.66* Mer5* Mer6* Mer6.88* pH 1 pH 2 pH 3 pH 4 pH 4.66 pH 5 pH 6 pH 6.88 0 0.960 2.01 3.050 4.05 4.680 5.060 6.040 6.980 5 0.990 2.01 3.050 4.04 4.680 5.050 6.020 6.950 10 0.990 2.01 3.030 4.02 4.670 5.020 6.010 6.920 15 0.990 2.00 3.010 4.01 4.670 5.010 6.000 6.900 20 1.000 2.00 3.000 4.00 4.660 5.000 6.000 6.880 25 1.010 2.00 3.000 4.01 4.660 5.000 6.020 6.
9 Annex Merck CertiPUR (25 °C) Temp. (°C) MerC4.01 MerC7.00 MerC9.00 MerC10.00 pH 4.01 pH 7.00 pH 9.00 pH 10.00 0 - - - - 5 4.00 7.09 9.22 10.22 10 4.00 7.06 9.16 10.16 15 4.00 7.04 9.10 10.10 20 4.00 7.02 9.05 10.05 25 4.01 7.00 9.00 10.00 30 4.01 6.98 8.96 9.94 35 4.03 6.98 8.93 9.90 40 4.03 6.97 8.89 9.86 45 4.05 6.97 8.87 9.80 50 4.06 6.97 8.84 9.
9.5 Remote box 9.5 Remote box The 6.2148.010 Remote box allows the control of Metrohm instruments which cannot be connected directly to the MSB interface of the pH/Ion Meter. This applies, for example, to Dosimat Plus devices, series 7xx stirrers and sample changers. The remote box therefore provides a connection between the MSB interface and the remote connection of the instrument to be controlled. Fig. 17: Connections of the optional 6.2148.
9 Annex 9.5.2 Functions of the individual remote lines Name Pin Input 0 21 Function Print/Start Outputs a measuring points or results report with stepping impulse (Output 3) Conc Cal Mode Conc pH Cal El.
9.6 Accessories 9.6 Accessories Up-to-date information on the scope of delivery and optional accessories for your instrument can be found on the Internet. When you receive your new instrument, we recommend downloading the accessories list from the Internet, printing it out and keeping it together with the manual for reference purposes.
9 Annex The Partslists webpage will be displayed. • Select the desired output language. • Enter the article number and click on the Generate PDF command. The PDF file with the accessories data will be created in the language selected.
9.7 Warranty (guarantee) 9.7 Warranty (guarantee) Metrohm guarantees that the deliveries and services it provides are free of defects in materials, design or manufacturing. The general warranty period is 36 months (exclusions below) from the date of delivery, or 18 months in the event of continuous operation. The warranty remains valid on the condition that the servicing is provided by a service organization authorized by Metrohm at defined intervals and with a defined scope.
9 Annex Metrohm also offers a 120-month spare parts availability guarantee and a 60-month PC software support warranty, calculated from the date on which the product is withdrawn from the market. The content of this warranty is the ability of the customer to obtain functioning spare parts or appropriate software support at market prices during the time of the warranty period. This does not apply for software products sold under the Metrohm NIRSystems brand.
9.
10 Index 10 Index < <>, <> ..................... 36, 37 <-/exp> .................................. 36 ................................... 36 ........................ 34 ......................... 34 ................................... 33 .............................. 37 ............................ 33 .................... 37 ...................... 37 ............................ 35 ..............................
10 Index Dialog language ..................... 48 Dilution Calc. parameter Conc ... 75 Dimensions ........................... 137 Direct ion measurement Parameter ...................... 71 Display .................................... 48 Dos.rate Parameter Conc Add ..... 82 Dosimat Plus Configuration ................. 52 Connection .................... 11 Setting ........................... 11 Drift Calibration parameter Conc .............................. 76 Calibration parameter pH ........................
10 Index Measured value display .......... 32 Measured values Printout........................... 44 Measured values memory .... 107 Measuring accuracy ............. 136 Measuring interval................. 135 Measuring parameters Conc .............................. 72 pH .................................. 56 T ..................................... 65 U .................................... 68 Measuring point report ........... 99 Measuring ranges ................. 136 Memory initialization .............
10 Index Limit monitoring ........... 110 Pin occupancy ............. 156 Report Arrangement .................. 98 Calibration data ........... 101 Calibration parameter Conc .............................. 76 Calibration parameter pH ....................................... 59 Configuration ......... 42, 103 Electrode test parameter ....................................... 64 Finishing line .................. 98 Measured values memory ..................................... 105 Measuring points ...........
10 Index Time interval Print criterion .................. 45 Storage criterion ............ 47 Validation ....................... 51 Time zone ............................... 49 Transport................................... 7 Troubleshooting .................... 113 U U mode Parameters .................... 68 U/pH curve ............................ 138 Unit Ion parameters .............. 72 Uoff 780/781 pH/Ion Meter, Manual Electrode test............... 129 USER ......................................
