The degree of activation of a GC disk electrode can be evaluated by looking at the difference in the peak potential for the redox couple of ferri/Ferrocyanide, which is expected to be close to 60 mV [9]. First, use a slurry of the 0.05 μm alumina to polish the electrode. You can add several scoops of alumina to a small wash bottle of high purity water, like NanopureTM, and squirt it on a clean ground glass plate. For optimum cleanliness it is wise to use gloves when handling the electrodes. This precaution is necessary so that skin oils do not get onto the electrode. Polish with light pressure following a figure 8 pattern for approximately 30 seconds. The electrode should then be immediately rinsed with water. It is suggested that the stream of water be directed against the surface of the electrode. Only high purity water is used throughout the activation process. In order to remove excess water, touch the outer edge of the electrode with a soft tissue paper like KimwipeTM.