Metrohm 757 VA Computrace Manual de usuario descargar pdf (Pagina 43)

3.2 VA measurement modes

757 VA Computrace – Software

SqW – Square Wave

General:

SqW or Square Wave voltammetry is primarly suitable for re-

versible electrode processes. It is used particularly for sensitive

stripping voltammetric determinations at the HMDE or RDE. The

SqW measurement mode can be set for the exploratory and de-

termination mode by selecting

SqW - Square wave

for the

Mode

pa-

rameter in the

EXPLORATORY SPECIFICATION

WORKING

METHOD SPECIFICATIONS

window.

Description:

For SqW voltammetry, a square wave alternating voltage with a

small, constant amplitude is superimposed on a stepwise rising

direct voltage ramp. The current i is measured as a function of the

voltage U at the maximum and minimum of the square wave volt-

age. The phase dependent differences between the two current

measurements give peak-shaped curves which are evaluated us-

ing linear, polynomial or exponential baselines.

Start potential

Voltage step

Voltage step time = 1 / Frequency

Peak voltage

Peak

height

Amplitude

i = i2 - i1

t (

)

t (

)

t (

)

t (

)

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Metrohm 757 VA Computrace Manual de usuario Pagina 43