Metrohm 757 VA Computrace - Manual (Page 41)

3.2 VA measurement modes
757 VA Computrace – Software
31
3.2 VA measurement modes
DP – Differential Pulse
General:
DP or Differential Pulse voltammetry is the most universal and
frequently used voltammetric measurement mode. It is equally
well suited for irreversible and reversible systems and offers a
high sensitivity. The DP measurement mode can be set for the
exploratory and determination mode by selecting
DP - Differential
pulse for the Mode parameter in the EXPLORATORY SPECIFICATION
or WORKING METHOD SPECIFICATIONS window.
Description:
For DP voltammetry, rectangular pulses with a constant amplitude
are superimposed on a stepwise rising direct voltage ramp. The
current
i is measured as a function of the voltage U immediately
before the pulse and at the end of the pulse. From the differences
between the two current measurements, peak-shaped curves are
obtained which are evaluated using linear, polynomial or expo-
nential baselines.
U
i
U
Start potential
Pulse
amplitude
Voltage step
Pulse
time Voltage step time
Peak voltage
Peak
height
t
i = i2 - i1
t (i1) t (i2) t (i1) t (i2)