Metrohm 817 Bioscan - Manual (Page 43)

3.1 Handling the 817 Bioscan
817 Bioscan
35
3 Operation
3.1 Handling the 817 Bioscan
General
Amperometric detection takes place with a flowing current and there-
fore with a chemical conversion of the analyte. The course of a chemi-
cal reaction depends directly on various physical parameters, among
other things. In order to obtain optimum measuring conditions (e.g.
stable baseline or reproducible signals) it is necessary to take the fol-
lowing points into consideration. Further information can be found in
Section 4.2.
Constant temperature
The 817 Bioscan allows the interior of the instrument to be kept at a
constant temperature of up to max. 60°C. The lower limit is the ambient
temperature plus 10 °C. Under IC Net you should activate the appropri-
ate oven-operating mode in the 817 method parameters and define the
temperature (see Section 3.2.2)
Constant pH
The characteristic current/potential curves of all electrochemically reac-
tive substances depend very strongly on the pH of the pH eluent used.
This means that you should prepare the eluent very carefully and check
its pH at regular intervals.
Pulsation-free eluent flow
Changes to the eluent flow should be avoided as far as is possible. The
6.2620.150 Pulsation Absorber is available for this purpose; it is
mounted between the 709 IC Pump and the injection valve as de-
scribed in Section 2.3.2.
Never make dry measurements
The flow-through measuring cell must not be switched on if it is not
being rinsed constantly by the eluent or if the measuring cell is not
connected up properly!