Consult with the laboratory supervisor about the content and format of your report for this experiment. Suggestions and questions to consider are as follows:
- Write a short summery of what you did in this experiment, noting any deviations or substitutions in the procedure.
- Show example stripping voltammograms for Pb at 2 or more concentrations. Plot Ip vs. Pb concentration (both the uncorrected and corrected for background) and from the plot, determine the concentration of the Pb in the unknown sample. [Note: If you could not detect a peak for Pb in your unknown, the amount of Pb is most likely below 10 ppb.]
- Were there other metals present in the water sample as evidenced by other peaks? If yes, how can you identify the metal or metals?
- If your unknown is tap water, the amount of Pb may depend on whether the water was left standing in the pipes for hours or days, or whether you let the water run for a few minutes before sampling. If time permits, you may wish to see whether there is a difference in the quantity of Pb depending on the sampling time.
- If time permits, make a run with 100 ppb without the co-deposition of Hg and report what you observed in the way of the Pb ASV wave shape and height, and compare it to the result with the Hg film.
Note: It is important to use high purity water throughout in making solutions and high purity reagents that are designated as being free of heavy metals. Besides trace amounts of Pb in reagents, copper is usually the main contaminant.