Metrohm 817 Bioscan - Manual (Page 55)

4.1 Introduction
817 Bioscan
47
4 Basic principles
4.1 Introduction
The 817 Bioscan can be operated as an amperometric detector in
three different working modes:
• DC mode
A constant potential is applied to the working elec-
trode. The analyte substances are oxidized or re-
duced according to their electrochemical properties.
The current that is produced is measured.
• Scan mode Current-potential curves are recorded in order to de-
termine the optimum parameters for pulsed am-
perometric detection. This is done by passing a so-
lution that contains only the substance of interest
through the measuring cell and recording a current-
potential curve.
• Pulse mode Three different potentials are applied cyclically to
the working electrode. This frees the electrode sur-
face from any adhering reaction products and reac-
tivates it for the next measurement. As this is the
operating mode that is primarily used with the 817
Bioscan for carbohydrate analysis it is described in
detail in Section 4.2.