Stripping Experiments: Pre-concentration Steps

Each voltammetric technique also has a stripping variation. For descriptions on the normal operation of the experiment, please read that specific help topic.

In any stripping experiment there are several steps prior to the start of the voltage scan. The purposes of these pre-experiment steps are

To (optionally) clean the electrode
To accumulate or concentrate the analyte on the electrode. The currents during the stripping scan are increased because of this accumulation.

This gives stripping voltammetric techniques their increased sensitivity.

You may use the Conditioning parameter to place the electrode in a reproducible state for each analysis. During this time the potentiostat’s stirring control bit is activated to sweep away reaction products. The potential may be selected to remove any impurities present on the electrode.

Following the (optional) Conditioning, the potential is set to the Initial potential and the Accumulation Time begins. During this time the analyte is accumulated (plated or adsorbed) on the electrode. The potentiostat’s stirring control bit is activated during this time to increase the efficiency of the accumulation. In general, the size of the analytical signal produced increases with increasing accumulation time. For very dilute solutions (parts per trillion!) you may choose an accumulation time of several minutes or more in order to accumulate a detectible amount of analyte.

Following the Accumulation time, the stirrer is turned off for a time specified by the Equilibration Time parameter. This allows the convection caused by the stirrer to dissipate before the scan begins. The cell switch remains in the ON position during this period. Although the choice of stirrer and cell design influence your choice for this parameter, 15 s is often sufficient. The Equilibration Time differs from the Quiet Time. During the Quiet Time the potentiostat’s cell switch is in the OFF position.

NOTE: Do not perform stripping experiments on a DME or SMDE.