Three activated C fresh and used for purifn. of cyclic erythromycine carbonate in AcMe-(CH(2)OH)(2) soln. and estazolam in iso-PrOH soln. under industrial conditions were tested by cyclic voltammetry to det. their surface deactivation. Powder and paste electrodes were prepd. and studied in HNO(3) and NaNO(3) solns. optionally in presence of Cu(NO(3))(2). The activated C from the erythromycine purifn. was the most contaminated adsorbent. It was confirmed by thermogravimetric measurements.