Metrohm 746 VA Trace Analyzer - Manual (Page 410)

5.7.3 Alphabetical instruction list
746 VA Trace Analyzer / 747 VA Stand
5-259
PSAMODE Page: O, S Stand: M, A Abbreviation: PS
Instructions t/s Main parameters Auxiliary parameters
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## .. PSAMODE .....
Function Measurement mode for Potentiometric Stripping Analysis.
Application Potentiometric stripping analysis is mainly used to determine substances
in an organic matrix with the aid of mercury film electrodes without prior
digestion.
Description In the PSAMODE measurement mode for potentiometric stripping analysis,
the analytes are deposited at the working electrode with the constant
voltage
U.start during a predetermined time t.depos and the voltage
U then measured for 6 s as a function of time. The nature of the
measurement is shown below using the RDE (mercury film electrode) as
an example.
Adjustable parameters:
PSWEEP
U.start
t.depos
Resolution
F (Hg film)
t
U
t
U.start
t.depos
t.meas = 6 s
In the PSAMODE measurement mode, the voltage measurement U vs t
(segment curves) is used to calculate the retention times t/U vs U
(substance curves). This results in peak-shaped curves which can be
evaluated automatically (see section 5.6.3). The peak voltage
U.peak is
characteristic of the substance, the peak area t.peak is proportional to
its concentration.
t/U
U U.peak
t.peak
Area (Hg film)