225 dme, O, s, M, a – Metrohm 746 VA Trace Analyzer User Manual
Page 376
5.7.3 Alphabetical instruction list
746 VA Trace Analyzer / 747 VA Stand
5-225
DME
Page:
O, S
Stand:
M, A
Abbreviation:
DM
Instructions t/s Main parameters Auxiliary parameters
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## .. DME .....
Function
Switch on Dropping Mercury Electrode (DME).
Description
The
DME
instruction is used to switch on the 6.1246.020 Multi-Mode
Electrode as a dropping mercury electrode, the mercury starts to flow out
freely. In a subsequent voltage sweep, the Hg drops are knocked off by
a tapping mechanism after the time
t.step
set in the measurement
mode.
t.step
t
F (Hg)
The set drop time
t.drop
important for certain parameter settings is
20 ms for the DME.
Comments
•
Within a program, the DME is not switched off until the
ØMEAS
instruction or the selection of a different electrode type (
HMDE
,
SMDE
or
RDE
). The DME is also switched off by
END
in the main program on
the "OP.SEQUENCE" page, but not by
END
in the segment.
•
The DME can be used for the following measurement modes and
sweeps:
DCTMODE
with
SWEEP
and
SSWEEP
,
DPMODE
with
SWEEP
and
FSWEEP
,
SQWMODE
with
SWEEP
and
FSWEEP
,
AC1MODE
with
SWEEP
,
AC2MODE
with
SWEEP
.
•
The following are not compatible with the DME:
CYCMODE
with
(CSWEEP
,
PSAMODE
with
PSWEEP
as well as
TSWEEP
.
•
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 sensitivity as the
electrode surface and hence the baseline constantly changes during
the measurement phase.
see also
HMDE, SMDE, RDE
Area (Hg)