GC electrodes can retain much of their activity by storing them in a solution of alumina or silica. To do this, add 6 or 7 scoops of either alumina or silica to about 25 ml of deionized water and stir the solution with the electrode in it. Essentially, the electrode is being continuously polished. When you are ready to use the electrode again, rinse it with a stream of pure deionized water and it is ready to go. The CV data for ferrocyanide oxidation, as a result of storing GC in alumina and silica, are tabulated in Table 1 and CVs are shown in Figures 3 and 4, respectively. Electrodes stored overnight in alumina or silica maintained a much higher degree of activation than when left exposed to air.
Table 1: Results of storing GC electrode in Solutions of Alumina or Fumed Silica
|Stored in Alumina||ΔEp, mV|
|a) Polished with alumina||72|
|b) Stored overnight in stirred alumina||103|
|c) Exposed to lab air for 4 hrs||144|
|Stored in Silica||ΔEp, mV|
|a) Polished with Silica||75|
|b) Stored overnight in stirred silica||123|
|c) Exposed to lab air for 4 hrs||195|
Figure 3. CV of 1 mM ferrocyanide in 1 M KCl a) with a freshly polished GC, b) after storage overnight in alumina, and c) after exposure to air for 4 hours.
Figure 4. CV of 1 mM ferrocyanide in 1 M KCl with a) freshly polished GC, b) stored overnight in silica, and c) after exposure to lab air for 4 hours.