Metrohm 757 VA Computrace - Manual (Page 38)

3 General settings for exploratory and determination mode
757 VA Computrace – Software
28
Voltage step time
t
Hg drop
surface
Notes:
• In the exploratory mode, the DME can be used for all meas-
urement modes except SqW, CV and PSA. In the determina-
tion mode, the DME can be used for all measurement modes
except DC, SqW, CV and PSA.
• An advantage of the DME compared with the SMDE is that
the MME capillary is subjected to less mechanical stress.
• A disadvantage of the DME compared with the SMDE and
HMDE is the higher mercury consumption and the lower sen-
sitivity as the electrode surface constantly changes during the
measurement phase.
SMDE
SMDE is an electrode mode of the Multi-Mode Electrode and
stands for
Static Mercury Drop Electrode. It combines the fea-
tures of the DME and the HMDE: as with the DME, the mercury
drops are constantly renewed, but during the measurement the
drop surface is constant as in the HMDE case. Each mercury
drop is knocked off by a tapping mechanism after the
Voltage step
time set in the measurement mode.
Drop size [ 1...9 ; 4 ]
Size of the mercury drop (surface 0.15 mm 2 ...0.60 mm 2 ).
t
Voltage step time Drop size
× 40 ms
Hg drop
surface