Metrohm 896 Professional Detector – Amperometry - Manual (Page 27)

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4 Start-up
2.896.0020 896 Professional Detector – Amperometry
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￭ Switch off the cell
With the cell switched off and detector hardware still running, the
signal should fall under 1 nA absolutely and noise be restrained to
the third decimal place.
Exactly even signals may indicate that new detector data is not
correctly transmitted.
The dummy cell incorporates a resistor (300 M Ω) and a capacitor (100 µF)
connected in parallel. If, in DC mode, a voltage of 0.8 V is applied, then a
current of 2.667 nA (± 7 %) is measured in the dummy cell. The capacitor
works as a noise generator and simulates a well-working measuring cell.
4.2 Testing the leak sensor
The leak sensor should not respond during the start-up. If the leak sensor
nevertheless does respond during the start-up, you will find information
for eliminating the problem in Chapter (see Chapter 6.1, page 31).
To check whether the leak sensor is functioning, proceed as follows:
Testing the leak sensor
1 Hold a cloth moistened with eluent or tap water on the two contacts
of the leak sensor .
The leak sensor of the detector responds.
If the leak sensor does not respond, please request Metrohm Service.
4.3 Testing the preheating capillary
The amperometric detector has a preheating capillary in its interior that
ensures that the eluent flows through the measuring cell at a constant
temperature. The preheating capillary need not however always be con-
nected. If the ambient conditions are optimal, then the measuring results
can be sufficiently accurate, even without the use of the preheating capil-
lary.
Caution
The preheating capillary may not be used when working with readily
flammable liquids.
The preheating capillary must be free of both leaks and blockages.