1. The sum of Bi, Se, Te does not exceed 0,0003%.
2. The sum of Ni, Zn, Si, Sn, Fe, Co does not exceed 0.0020%.
3. The sum of P, Cr, Mn, As, Cd, Sb does not exceed 0.0015%.
4. Total amount of the normalized impurity, except for oxygen, no more than 0,0065%.
Cathodes correspond to the Cu-CATH-1 brand according to the English BS EN 1978:1998 standard.