- Use an analog or computer-controlled potentiostat with appropriate data acquisition equipment for this experiment (ask your lab instructor for directions on use of potentiostat)
- Electrochemical cell and electrodes
- Small volume cell
- 1.0 mm or 3.0 mm flat tipped glassy carbon electrode
- Pt auxiliary electrode
- Ag/AgCl reference electrode
- Polishing kit
- A magnetic stirrer and a small bar inside the cell
- A timer
- 50 ml and 100 ml volumetric flasks
- Prepare three separate 100 mL solutions at 100 ppb, 500 ppb and 1,000 ppb of Pb(NO3)2 containing 0.1 M KNO3, 50 mM HNO3 and 40 ppm Hg(NO3)2. Use doubly distilled water or other high purity water for dilutions.
- Prepare a background solution containing 0.1 M KNO3, 50 mM HNO3 and 40 ppm Hg(NO3)2.
Dilute a sample of tap water or an unknown sample from your instructor. Prepare the sample by adding an equal volume of 0.1 M KNO3 containing 50 mM HNO3 and 40 ppm Hg(NO3)2.
Note: It is important that glassware is cleaned thoroughly, rinsed several times with pure water and then dried prior to use. You should look at the bottle labels of chemicals to note the amount of heavy metal impurities, if any are present. High purity reagents, absent of heavy metal impurities, can be purchased. Discuss this issue with the laboratory instructor. Calibration using the method of standard addition can correct for impurity if it is the same as the sought for metal.