Metrohm 757 VA Computrace - Manual (Page 47)

3.2 VA measurement modes
757 VA Computrace – Software
37
NP – Normal Pulse (for "Exploratory" only)
General:
NP or Normal Pulse voltammetry is the classic pulse voltam-
metric measurement mode with direct recording of the current. It
is equally well suited for irreversible and reversible systems and
offers a higher sensitivity than the DC voltammetry. The NP
measurement mode can only be set for the exploratory mode by
selecting
NP - Normal pulse for the Mode parameter in the
EXPLORATORY SPECIFICATION window.
Description:
For NP voltammetry, square-wave pulses with an increasing am-
plitude are superimposed on a constant base voltage. The cur-
rent
i is measured as a function of the voltage U at the end of the
pulse. This normally provides wave-shaped curves which can be
evaluated using the tangent method.
U
Base potential
Voltage
step
Pulse
time Voltage step time
t (i) t (i)
Start potential
Half-wave voltage
Wave current
i
U