runge mikron 81 User manual

mikron 81 conductivity meter
Operations manual
mikron 81
leitfähigkeitsmeßgerät

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© 2021
Wissenschaftliche Gerätebau „F. F. Runge“ Gmb
(“F. F. Runge” Scientific Instruments)
David-Gilly-Straße 1
14469 Potsdam
Germany
Telephone +49 (0) 3 31 / 96 79 75 00
Telefax +49 (0) 3 31 / 96 79 75 02
E-Mail [email protected]
Internet www.ff-runge.de
We reserve the right to make changes
Reprints – even for excerpts – not permitted
Runge is a registered trademark of Wissenschaftliche Gerätebau „F. F. Runge“ Gmb .
Any other marks and protected trademarks named in the following are the property of their respective owners.
Printed in Germany 81.6A0.2106.en

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Table of contents
Introduction............................................................................................................................................................ 5
Safety regulations............................................................................................................................................... 6
Intended use...................................................................................................................................... 6
Occupational safety......................................................................................................................... 7
Ambient conditions........................................................................................................................... 7
An overvie of the detector........................................................................................................................... 8
Technical data....................................................................................................................................................... 9
Method of measurement.............................................................................................................................. 10
Equipment delivered...................................................................................................................... 11
Setting up............................................................................................................................................................. 12
Mounting, fastening....................................................................................................................... 12
Liquid connectors.......................................................................................................................... 14
Electrical connection..................................................................................................................... 15
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Operation.............................................................................................................................................................. 16
Switching on and off...................................................................................................................... 16
Display of the operating status.................................................................................................... 16
Choice of data rate and time constant...................................................................................... 17
Measurement by temperature equalisation............................................................................... 18
Determining the specific temperature coefficient for the material........................................19
Rinsing, cleaning and storing the measurement cell...............................................................19
Replacing the measurement cell................................................................................................. 20
Calibration....................................................................................................................................... 22
Trouble shooting............................................................................................................................................... 23
Annexe 1: Spare parts list............................................................................................................................ 25
Annexe 2: GLP detector specifications.................................................................................................. 27
Conformity declaration.................................................................................................................................. 29
UK Declaration of Conformity acc. to BS EN ISO/IEC 17050-1...............................................30

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Introduction
Thank you for deciding for a Runge detector.
Our mikron apparatus differs both in its concept and size from traditional detectors: it gives
you the the performance of advanced laboratory detectors in the form of a test head. This
gives you new application possibilities. Important aims in its development were durability,
ease of maintenance and a good price/performance ratio.
We develop and produce all Runge instruments in Germany. We rely on competent
suppliers in Brandenburg and in Berlin. We hope that you will be satisfied with our detector
in its day to day usage and that we can gain your long-term custom.
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Safety regulations
This detector meets the prescribed safety regulations. Incorrect operation can however lead
to injury and damage. Consequently read these operating instructions carefully before put-
ting the detector into operation.
Runge cannot accept responsibility for damage caused by not following these instructions.
Intended use
This detector is to be used in analytical and preparative liquid chromatography equipment
and in general for the photometric analysis of liquids. The insertion and operation of the
detector shall only be carried out by trained laboratory technicians with knowledge in this
field and experience in handling the chemicals used.

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Occupational safety
When using the apparatus observe the health and safety regulations (among others those
concerning protective clothing and laboratory equipment). In the United Kingdom, relevant
information is provided by the ealth and Safety Executive. In Ireland it is the ealth and
Safety authority, in Australia, Safe Work Australia and in New Zealand, Worksafe. In the
United States of America it is the OS A, in Canada the CSC.
Ambient conditions
The detector is to be operated only in the following conditions:
•Temperature 3...45 °C (37.4...113 °F)
•umidity 0...90 %, non-condensing
•Atmosphere: air in room, inert gas, no explosive or corrosive fumes
•No direct sunlight (danger of overheating)
•No ignition sources in the vicinity of flammable solvents
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An overvie of the detector
1 2
3
4
5
6
3
3
3
1 measurement cell (various types can be supplied)
2 detector block
3 liquid joint
4 status indicator
5 electrical connection (USB-C or RS-485)
6 name plate
Fig. 1: The mikron 81 detector

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Technical data
Type mikron 81, conductivity meter
Conduct. measuring range mS/cm (Z=10/cm) indicating 0.002 … 100 linear 0.002 … 100
mS/cm (Z=50/cm) indicating 0.010 … 500 linear 0.010 … 300
Conductivity accuracy % (Z=10/cm) ±2 % / ±1 mS/cm (the higher value applies)
(Z=50/cm) ±2 % / ±2 mS/cm (the higher value applies)
Conductivity scanning rate z 10
Temperature meas. range °C 0 … 100 +/– 0,1
Temperature scanning rate z 10
Power take-up W < 2,5
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Method of measurement
The concentration, valence and mobility of the ions dissolved in the liquid indicates its
composition, for example the salt content. The electric conductivity of the liquid is
proportional to the aforementioned ion properties, with their mobility depending on the
temperature of the liquid. The conductivity is measured with a high degree of accuracy by
applying an AC voltage to a cuvette (either filled with the liquid or subjected to a flow of the
liquid) of known measurements (cross-sectional area, separation of the electrodes) via the
zero voltage point (UW = 0) of a Wien bridge.
2
3
1
1 measuring cell
2 electrode
3 sample
Across-section
ldistance
G conductance
Zimpedance
Uq~ source voltage
UW Wien voltage
l
Gcell
σ=
R1
Z3
Fig. 2: Using a Wien measurement bridge for measuring electrical conductivity
[σ]= S/m
Al
2 2
Zcell
U
R2
Zcell
q~
U
q~
UW
V
3A

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By using alternating current, polarisation of the investigated liquid during time-consuming
measurements is avoided. The influence of the liquid’s temperature is compensated for. By
using a number of measurement cells differing from each other, each with its own geometry,
the measurement range of the detector can be adapted for the measurement task in each
case. The materials moistened by the liquid (PEEK for the body of the cell, titanium for the
electrodes, PTFE for the seals) are biologically compatible.
Equipment delivered
•Runge mikron 81 conductivity meter
•connecting cable for USB-C to USB-A
•operating instructions
•two pairs of liquid screw joints of the appropriate size
•size 3 Allen key
•table mounting1
1 may vary depending on the scope of delivery ordered
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Setting up
Mounting, fastening
With the table mounting delivered, the mikron 81 detector can be operated in a laboratory,
but can also be inserted into a device insofar as the ambient conditions (temperature,
humidity, composition of the atmosphere) are maintained.
When inserting the apparatus into a device, fastening it at the front of the detector block is
recommended (see Fig. 4), as this would not constrict the cross-section and otherwise the
housing would be deformed. A suitable means of fastening is, for example, pipe clips
conforming to DIN 3015.
As liquid only flows through the measurement cell, a leak can occur in the cell. To avoid
damage to electronic parts of the detector through the presence of liquid, it is recom-
mended when inserting the measurement cell vertically or at an angle to ensure that its end
cap is located at the deepest point. In the case of horizontal insertion the longitudinal
alignment groove should be situated at the bottom along with the overflow outlet of the

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measurement cell (Fig. 6). As leakages are not recognised by the detector, care must be
taken that leakages are discovered in time.
1
1 outlet overflow
2 alignment groove
Fig. 3: Table mounting Fig. 4: Preferred position for fastening clip
Fig. 5: Measurement cell at the bottom Fig. 6: Alignment groove at the bottom
2
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Liquid connectors
The mikron 81 detector can be fitted with various measurement cells. These cells use the
following joints:
Part number Cell constant (1/cm) Cell geometry Joint
81.240.0101 10 Vcell = 53 µl, di, bore = 2.2 mm 1/4″-28 UNF flat
81.240.0102 50 Vcell = 11 µl, di, bore = 1.0 mm 1/4″-28 UNF flat
Two pairs of appropriate joints are supplied with the apparatus. The order of the joints is
shown in Fig. 7.
Only PEEK joints should be used with this detector. They must be tightened with a torque
of 0.5 Nm. Joints of PEEK (polyether ether ketone) are not suitable for all operating
pressures and solvents.

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Electrical connection
The mikron 81 is connected to a computer via a USB connector and is controlled and
supplied with energy via the connector. The USB-C type plug is constructed symmetrically
and hence can be plugged in in two directions.
Fig. 7: Liquid joints, alignment of the parts
1/16″1/8″
2 12
1 Knurled-head screw 1/4″-28 UNF�
2 Ferrule
3 Tubing
3
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Operation
S itching on and off
The detector is supplied via the USB connector with power and is switched on as soon as
the supply voltage is applied, i.e. as soon as the connected computer or active USB hub is
switched on. The light source(s) are switched on and off via a separate command.
Display of the operating status
The mikron 81 detector can only be remotely controlled via a computer. The apparatus has a
3-coloured status display. This can show the following three operating states:
Colour Type Meaning
green steady light operational
green flashing light measurement in process

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Colour Type Meaning
yellow steady light startup test in process
red steady light error
Choice of data rate and time constant
Data rate and time constants concern the processing of the measured signal in the detector
before outputting to the computer. The data rate determines the quantity of data points per
second on the time axis of the chromatogram, and the time constant defines the
communication of the signal within the chosen time interval. The longer the interval, the
lower the noise level, and the time-based resolution is also lower. This should be kept in
mind when choosing the constant.
A data rate is recommended which is more than double the reverse value of the time
constant, so that at least two data points are located in an interval of the time constant. At
the same time the data rate should be so chosen that the narrowest expected peak in the
chromatogram is defined with at least 20 data points.
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In the case of an unknown duration of the signal peaks it is recommended to make a
chromatogram with time constant = 0 ms or = 10 ms and to choose a time constantτ τ
shorter than half of the narrowest amplitude.
Measurement by temperature equalisation
The temperature of a solution has an influence on its electrical conductivity. This
dependency is linear for most materials, as shown in Fig. 8, equation 1. For a few materials
e.g. natural water, a non-linear function in accordance with DIN 7888 is applicable. The
mikron 81 is fitted with a linear temperature equalisation device. Furthermore, the specific
temperature coefficient (in %/°C) of the material investigated, which can be looked up in
chemical tables, will be added to the chromatography programme.
σ
ϑ
100 + cϑ(ϑ – ϑref )
σ(ϑref )
σ(ϑ) =
Fig. 8: Linear temperature dependence of electrical conductivity
100
(σ(ϑ2 ) – σ(ϑref ))· 100
cϑ(ϑ2 – ϑref ) · σ(ϑref )
(1)
(2)
electrical conductivity
temperature
S/m
°C
cϑ
ref
specific temperature coefficient
reference
%/°C
=

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Determining the specific temperature coefficient for the material
If the electrical conductivity of the material to be investigated is known for a particular
temperature (reference temperature) but the temperature coefficient is not known, the latter
can be calculated by measuring the conductivity at another temperature using equation 2 of
Fig. 8. In this case, the temperature equalisation function of the mikron 81 must be switched
off. The measurement temperature should be at least 10 °C higher than the reference
temperature.
Rinsing, cleaning and storing the measurement cell
The cleanliness of the measurement cell is critical for the accuracy and reproducibility of the
measuring result. It is recommended to rinse out the measurement cell with distilled water
between measurements.
When cleaning a significantly soiled cell a cleaning solution is recommended which consists
in equal parts of isopropyl alcohol and a 32% solution of hydrochloric acid. The cell is filled
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with this solution, exposed to it for two or three minutes and then rinsed out thoroughly
several times with distilled water.
When storing the measurement cell for some time without use (longer than two weeks) the
cell is first of all rinsed or cleaned and residual liquid is then forced out from the cell’s
interior using compressed air.
Replacing the measurement cell
Before disassembling the detector it must be ensured that it is not under electric tension
(plug removed). After the Allen screws visible at the end cap have been loosened they can
be removed using the spanner supplied.
The parts of the detector remain attached to each other as a result of the spring tension of
the plug even after the screws have been loosened. When reassembling the apparatus with
a new measurement cell or one of the same type, alignment grooves and the position of the
plugs aid the correct settings of the cell.