Metrohm 780 User manual

780 pH Meter / 781 pH/Ion Meter
Manual
8.781.8002EN / 2014-07-31

Metrohm AG
CH-9100 Herisau
Switzerland
Phone [phone]
Fax [phone]
[email protected]
www.metrohm.com
780 pH Meter / 781 pH/Ion Meter
Program Version 5.780.0020 und 5.781.0020
Manual
8.781.8002EN / 2014-07-31 jb/ebe

Teachware
Metrohm AG
CH-9100 Herisau
[email protected]
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
780/781 pH/Ion Meter, Manual
I
Table of contents
1Introduction..........................................................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 .........................................................................5
1.4 Safety information ........................................................................................6
1.4.1 Electrical safety ........................................................................................6
1.4.2 General handling rules .............................................................................6
2Installation ...........................................................7
2.1 Instrument setup ..........................................................................................7
2.1.1 Packaging.................................................................................................7
2.1.2 Checks......................................................................................................7
2.1.3 Location ....................................................................................................7
2.2 Connecting the accessories ........................................................................8
2.3 Connecting optional devices .......................................................................9
2.3.1 Connecting the 801 Magnetic Stirrer .......................................................9
2.3.2 Connecting the 802 Rod Stirrer..............................................................10
2.3.3 Connecting a Dosimat Plus (only 781) ..................................................11
2.3.4 Connecting a sample changer...............................................................12
2.3.5 Connecting a printer...............................................................................13
2.3.6 Connecting a computer .........................................................................15
2.4 Connecting the electrodes and sensors ...................................................16
2.5 Mains connection .......................................................................................17
2.6 Switch on ....................................................................................................17
2.7 Initial configuration ....................................................................................18
3Short operating tutorial .....................................19
3.1 pH measurement ........................................................................................19
3.1.1 Requirements .........................................................................................19
3.1.2 Preparations ...........................................................................................19
3.1.3 pH calibration .........................................................................................20
3.1.4 pH measurement....................................................................................22
3.2 Determination of an ion concentration (only 781: Conc mode) ...............23
3.2.1 Requirements .........................................................................................23
3.2.2 Preparations ...........................................................................................23
3.2.3 Calibrating the fluoride ISE.....................................................................24
3.2.4 Direct measurement of fluoride..............................................................28
4Operation ...........................................................31
4.1 The keypad .................................................................................................31
4.2 Operating concept .....................................................................................32
4.3 All key functions at a glance......................................................................33
4.4 Operating principles ..................................................................................38
4.4.1 Configuration and method parameters .................................................38
4.4.2 Editing menu entries ..............................................................................38
4.4.3 Entering text............................................................................................39

Contents
II
780/781 pH/Ion Meter, Manual
5Configuration .....................................................41
5.1 Report.........................................................................................................42
5.2 Printing out measured values....................................................................44
5.3 Storing measured values ...........................................................................47
5.4 Auxiliaries...................................................................................................48
5.5 Monitoring ..................................................................................................51
5.6 Peripheral units..........................................................................................52
5.7 RS232 settings ...........................................................................................54
6Methods / Parameters........................................55
6.1 Method management .................................................................................55
6.2 pH measurement (pH mode) .....................................................................56
6.2.1 Measuring parameters...........................................................................56
6.2.2 Calibration parameters...........................................................................58
6.2.3 Limits pH ................................................................................................62
6.2.4 Limits T ...................................................................................................62
6.2.5 Plot parameters ......................................................................................63
6.2.6 Preselections..........................................................................................63
6.2.7 Electrode test .........................................................................................64
6.3 Temperature measurement (T mode)........................................................65
6.3.1 Measuring parameters...........................................................................65
6.3.2 Limits T ...................................................................................................66
6.3.3 Plot parameters ......................................................................................67
6.3.4 Preselections..........................................................................................67
6.4 Potential measurement (U mode)..............................................................68
6.4.1 Measuring parameters...........................................................................68
6.4.2 Limits U...................................................................................................69
6.4.3 Plot parameters ......................................................................................70
6.4.4 Preselections..........................................................................................70
6.5 Direct ion measurement (781 only: Conc mode) ......................................71
6.5.1 Type of measurement ............................................................................71
6.5.2 Ion parameters .......................................................................................71
6.5.3 Measuring parameters...........................................................................72
6.5.4 Calculation parameters ..........................................................................74
6.5.5 Calibration parameters...........................................................................75
6.5.6 Limits Conc ............................................................................................77
6.5.7 Limits T ...................................................................................................78
6.5.8 Plot parameters ......................................................................................78
6.5.9 Preselections..........................................................................................79
6.6 Standard and sample addition (781 only: Conc mode) ............................80
6.6.1 Standard / Sample addition ...................................................................80
6.6.2 Preselections..........................................................................................83
7Various functions ...............................................85
7.1 Calibration and addition/subtraction data ................................................85
7.1.1 pH calibration data.................................................................................85
7.1.2 Conc calibration data (781 pH/Ion Meter only) .....................................89
7.1.3 Addition/Subtraction data (781 pH/Ion Meter only)...............................93
7.2 Reports .......................................................................................................96

Contents
780/781 pH/Ion Meter, Manual
III
7.2.1 Arrangement of a report .........................................................................98
7.2.2 Report identification ...............................................................................99
7.2.3 Measuring point report ...........................................................................99
7.2.4 Calibration report..................................................................................101
7.2.5 Result report (781 pH/Ion Meter only)..................................................102
7.2.6 Configuration report .............................................................................103
7.2.7 Parameter report ..................................................................................104
7.2.8 Measured values memory report .........................................................105
7.2.9 User method report ..............................................................................106
7.3 Measured values memory........................................................................107
7.3.1 Save measured values .........................................................................107
7.3.2 Print measured values..........................................................................107
7.3.3 Show measured values ........................................................................108
7.4 Limit monitoring .......................................................................................109
7.4.1 Uses......................................................................................................109
7.4.2 How it functions ....................................................................................110
7.5 Setup ........................................................................................................111
7.5.1 Locking .................................................................................................111
7.5.2 Input assignment..................................................................................112
7.5.3 Graphics ...............................................................................................112
8Troubleshooting – Messages – Maintenance ..113
8.1 Troubleshooting .......................................................................................113
8.2 Messages .................................................................................................115
8.3 QM support...............................................................................................120
8.4 Validation..................................................................................................122
8.4.1 Electronic tests .....................................................................................122
8.4.2 Wet tests...............................................................................................123
8.4.3 pH/Ion Meter maintenance...................................................................123
8.5 Diagnosis..................................................................................................124
8.6 pH electrode test......................................................................................126
8.6.1 Preparations .........................................................................................126
8.6.2 Procedure .............................................................................................127
8.6.3 Results ..................................................................................................129
8.6.4 Messages and measures.....................................................................131
8.6.5 Care and maintenance of pH glass electrodes...................................132
9Annex................................................................135
9.1 Technical data ..........................................................................................135
9.1.1 Measuring modes ................................................................................135
9.1.2 Measuring inputs..................................................................................135
9.1.3 Measuring input specifications ............................................................136
9.1.4 Interfaces ..............................................................................................136
9.1.5 Power supply ........................................................................................136
9.1.6 Safety specifications ............................................................................137
9.1.7 Electromagnetic compatibility (EMC) ..................................................137
9.1.8 Ambient temperature............................................................................137
9.1.9 Reference conditions ...........................................................................137
9.1.10 Dimensions...........................................................................................137
9.2 Evaluation.................................................................................................138

Contents
IV
780/781 pH/Ion Meter, Manual
9.2.1 pH calibration .......................................................................................138
9.2.2 Calibration for ion measurements........................................................142
9.2.3 Addition method...................................................................................143
9.3 Menu structures .......................................................................................144
9.3.1 Instrument configuration ......................................................................144
9.3.2 Method parameters in the pH mode ...................................................146
9.3.3 Method parameters in the T mode ......................................................147
9.3.4 Method parameters in the U mode......................................................147
9.3.5 Method parameter in the Conc mode .................................................148
9.4 Stored buffer series .................................................................................150
9.5 Remote box ..............................................................................................156
9.5.1 Pin occupancy of the remote connection of the Remote box.............156
9.5.2 Functions of the individual remote lines ..............................................157
9.6 Accessories..............................................................................................158
9.7 Warranty (guarantee) ...............................................................................160
10 Index.................................................................163

Contents
780/781 pH/Ion Meter, Manual
V
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. 5: Attaching the support rod and base plate..................................................................... 8
Fig. 6: Ready-mounted pH/ISE measuring system.................................................................. 9
Fig. 7: 780 pH Meter / 781 pH/Ion Meter – 801 Magnetic stirrer.............................................. 9
Fig. 8: 780 pH Meter / 781 pH/Ion Meter – 802 Rod stirrer .................................................... 10
Fig. 9: 781 pH/Ion Meter – Dosimat Plus................................................................................ 11
Fig. 10: 781 pH/Ion Meter – Dosimat Plus – Sample changer............................................... 12
Fig. 11: 780 pH Meter / 781 pH/Ion Meter – Printer ............................................................... 13
Fig. 12: Connecting sensors................................................................................................... 16
Fig. 13: Remote outputs in limit monitoring.......................................................................... 110
Fig. 14: Diagram showing changes in potential during an electrode test ........................... 129
Fig. 15: Theoretical U/pH relationship ................................................................................ 138
Fig. 16: 3-Point pH calibration .............................................................................................. 139
Fig. 17: Connections of the optional 6.2148.010 Remote box............................................. 156
Fig. 18: Pin occupancy at remote interface.......................................................................... 156

1 Introduction
780/781 pH/Ion Meter, Manual
1
1Introduction
This Manual provides you with a comprehensive overview of the instal-
lation, 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. The
special measuring mode of the 781 pH/Ion Meter – the measurement of
concentration – is, like the other measuring modes, described in sepa-
rate sections. These sections, which apply only to the operation of the
781 pH/Ion Meter, are marked accordingly.
Information about the use of Metrohm pH or ion-selective electrodes
can be found in the appropriate leaflet and the ISE Manual that is in-
cluded with the electrode.
Additional theoretical principles can be found in the Metrohm Mono-
graph "
Electrodes in Potentiometry
".
You can also request our descriptions of applications involving pH and
ISE measurements in the form of
Application Notes
and
Application
Bulletins
from your local Metrohm agency or download them from the
Internet under www.metrohm.com.
Fig. 1: 781 pH/Ion Meter connected to 801Magnetic Stirrer
1.1 Instrument description
Both instrument versions, the
781 pH/Ion Meter
and the
780
pH Meter,
are used for measuring pH, temperature and potential reliably and at
high resolution. The
781
pH/Ion Meter
differs from the
780
pH Meter
by
having an additional operating mode for the potentiometric determina-
tion of the concentration by using ion-selective electrodes (
Conc
mode
).
Both instruments have comprehensive monitoring functions (for calibra-
tion, validation and service intervals), diagnostic functions and an au-

1.1 Instrument description
2
780/781 pH/Ion Meter, Manual
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 comput-
er for output as a report.
Both instruments have the following features:
•Dot-matrix display for both the continuous display of the measured
value and for showing the user dialog.
•High-impedance measuring input for pH, redox or ISE sensors, a
connection for a separate reference electrode and an input for tem-
perature sensors (Pt1000 or NTC).
•MSB connection (Metrohm Serial Bus) for a stirrer and for a
Dosimat Plus.
•RS 232 connection for a serial printer or a computer.
•A connection for an external keyboard or a barcode reader.
The
781
pH/Ion Meter
has an additional
Conc
mode
which allows the
measurement of the concentration by using ion-selective electrodes, ei-
ther directly after calibration or by standard or sample addition meth-
ods. Such a
calibration
or
standard addition
can be carried out either
manually or automatically. In the latter method a standard solution is
added automatically by a Dosimat Plus included in the system. The cal-
ibration concentrations or the standard additions are calculated auto-
matically according to the given conditions and these are added with
great accuracy.

1 Introduction
780/781 pH/Ion Meter, Manual
3
1.2 Parts and controls
Fig. 2: Front view of the 780 pH Meter or 781 pH/Ion Meter
1
LCD display
3
Main function keys
2
On/Off key
Key for switching the instrument on and
off
4
Input, navigation and
function keys
Each key has several functions;
the particular function depends on the
work status of the instrument

1.2 Parts and controls
4
780/781 pH/Ion Meter, Manual
Fig. 3: Rear view of the 780 pH Meter or 781 pH/Ion Meter
5
Connection for potentiometric electrodes
pH, ISE, redox or silver electrodes
with built-in or separate reference elec-
trode; socket type F
10
RS232 interface
Connection for printer or PC
6
Connection for separate reference
electrode
4 mm socket type B
11
Barcode reader/
Keyboard connection
7
Serial number
12
12V power connection
8
Connection for temperature sensor
Pt1000 or NTC, for connection with two 2
mm B-plugs; 6.2103.130 and 6.2103.140
Adapters are included for use with 4 mm
banana plugs
13
Grounding connection
For measurements in grounded solu-
tions, grounding of the instrument
may be advantageous to avoid inter-
ferences; 4 mm socket type B
9
MSB connection
(Metrohm Serial Bus) for connecting a
stirrer and/or Dosimat Plus
, directly or via
the optional Remote Box (6.2148.010)

1 Introduction
780/781 pH/Ion Meter, Manual
5
1.3 Information about this Manual
Please study this Manual carefully before you start to use the instru-
ment. The Manual contains information and warnings that must be ob-
served by the user in order to guarantee the safe use of the instru-
ment.
1.3.1 Notation and pictograms
The following notations and pictograms (symbols) are used in this
Manual:
Range
Menu item, parameter or input value
<MODE>
Key
12
Operating element
Danger
This symbol indicates a possible risk of death
or injury if the given information is not properly
observed.
Warning
This symbol indicates a possible risk of dam-
age to the instrument or its components if the
given information is not properly observed.
Attention
This symbol indicates important information.
Please read it carefully before you continue.
Information
This symbol indicates additional information
and tips.
TIP !
TIP
This symbol indicates information that may be
of particular use to you.

1.4 Safety information
6
780/781 pH/Ion Meter, Manual
1.4 Safety information
Warning!
This instrument should only be used in accordance with the infor-
mation 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.
Electrical safety when handling the 780 pH Meter and the 781 pH/Ion
Meter is guaranteed within the framework of the IEC 61010 Standard.
The following points must be observed:
Please make sure that the external power supply is always kept dry.
Protect it against direct liquid contact .
Electronic components are sensitive to electrostatic charges and can
be destroyed by a discharge. Always switch off the pH/Ion Meter be-
fore making or breaking electrical connections on the rear panel of the
instrument.
1.4.2 General handling rules
Handling solutions
When worki
ng with water or other solutions in the immediate vicinity of
the pH/Ion Meter please avoid excessive liquid splashes on the in-
strument housing or power supply. Any such splashes must be re-
moved as quickly as possible in order to prevent the liquid from enter-
ing the instrument or the power supply.

2 Installation
780/781 pH/Ion Meter, Manual
7
2Installation
2.1 Instrument setup
2.1.1 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 guar-
anteed. Should you wish to dispose of it please consider suitable dis-
posal or recycling processes.
2.1.2 Checks
Please check that the delivery is complete and undamaged immediate-
ly on receipt (compare with delivery note and list of accessories given in
Section 9.6).
2.1.3 Location
Place the instrument on a suitable vibration-free laboratory bench, pro-
tected from corrosive atmospheres and contact with chemicals.

2.2 Connecting the accessories
8
780/781 pH/Ion Meter, Manual
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 sup-
plied
stand base
.
You can chose between the arrangements shown in Fig. 4 to suit your
own particular working preference.
Fig. 4: Possible arrangements for mounting the base plate
Versions
A
and
B
are intended for mounting an 801 Magnetic stirrer on
the left- and right-hand side of the pH/Ion Meter respectively. If you fre-
quently work without such a permanently attached stirrer then you can
mount the base plate so that you have space for the sample vessel di-
rectly in front of the support rod (versions
C
and
D
).
Attach the base plate with the screws provided as shown in Fig. 5. The
rubber feet included prevent the system from slipping about on the
work bench and should therefore be stuck on to the base plate.
Fig. 5: Attaching the support rod and base plate

2 Installation
780/781 pH/Ion Meter, Manual
9
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 con-
nection
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 (6.2013.010) and the electrode holder (6.2021.020). Fur-
ther details are given in the corresponding Manual.
For example, the ready-mounted system could look like this:
Fig. 6: Ready-mounted pH/ISE measuring system
The
801
Magnetic Stirrer
is controlled via MSB connection
9
. The stirrer
is connected to it directly:
Fig. 7: 780 pH Meter / 781 pH/Ion Meter – 801 Magnetic stirrer

2.3 Connecting optional devices
10
780/781 pH/Ion Meter, Manual
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. 8: 780 pH Meter / 781 pH/Ion Meter – 802 Rod stirrer