Metrohm 757 VA Computrace - Manual (Page 55)

3.3 Potentiostat
757 VA Computrace – Software
45
Notes:
• The AC measurement mode can be used with all types of
electrodes.
• The following condition applies to the definition of the
Modula-
tion time :
Modulation time > 2 / Frequency
Modulation time < voltage step time + 0.45 s
• The measurement time
t (i) is defined as follows:
t (i) = Modulation time / 2
3.3 Potentiostat
The potentiostat built-in in the 757 VA Computrace Stand normally
works with full sensitivity for current measurements from 100 pA
to 30 mA. Depending on the measured current, the current range
will be selected automatically between the lowest and the highest
current range. For fast measurements with CV, SqW or DC it may
be sometimes helpful to limit the highest and/or lowest current
range in order to avoid disturbing current leaps.
Highest current range [ 100 nA, 1/10/100 µA, 1/10 mA ; 10 mA ]
Limitation of the highest current range.
Lowest current range [ 100 nA, 1/10/100 µA, 1/10 mA ; 100 nA ]
Limitation of the lowest current range.
3.4 General operation sequence
Overview of operation sequence
The general operation sequence for measurements is identical for
both the exploratory and the determination mode and includes
the following steps:
1.
Stirring
Optional stirring of the sample solution during preparation
procedures until start of the equilibration time (details see Stir-
ring).