Procedure:
Take 90cm3 of the supporting electrolyte within the cell, erase dissolved air along with pure nitrogen at -1.20 V vs. SCE applied to the cathode as define in the common procedure and stop the electrolysis while the background current has decreased a constant value - 2 mA. It commonly takes 30 -60 minutes. Attach the coulometer and adjust the potentiostate to manage the potential of the cathode at - 0.95 V vs. SCE for nickel and -1.20V vs. SCE for cobalt determinations. Pipette 20 cm3 of the sample solution holding cobalt and nickel. Continue the electrolysis under automatic control until the current decreases to a minimal volume (2-3 hours for every metal).
Record the total quantity of electricity passed from the coulometer readings, the electrolysis time and search current. Compute the mass of every metal deposited at each potential by using the following relationship
m = M r × I × t /n × F