From the two standard additions of 50 pm Fe(III) in the figure, find the concentration of Fe(III) in the seawater. Estimate where the baseline should be drawn for each trace and measure the peak height from the baseline. Consider the volume to be constant for all three solutions.

Cathodic stripping voltammetry (CSV) is the quantification of metals species from their reduction current. The stripping bit means that there is a preconcentration step that usually consists of the adsorption of a complex with a selective ligand (usually an organic ligand) on the electrode. The metal in the complex is reduced. The sensitivity is very good because the adsorption forms a single molecular layer that is reduced in its entirety. There is no diffusion during the scan so a high scan rate can be used which gives a high sensitivity. The sensitivity of CSV is sufficient to detect about 20 elements in seawater. In the electrochemical reactions, the relation between current and voltage is noted and this technique is called voltammetry. A graph that represents current Vs voltage is called a voltammogram.

The spreadsheet for the addition of iron (III) in seawater.

The B13 and B18 cells in the spreadsheet gives the concentration of Fe[III] is$104\pm 13\mathrm{pM}$.