1. DEPARTMENT OF ANALYTICAL CHEMISTRY, FACULTY OF TECHNOLOGY AND METALLURGY, UNIVERSITY OF BELGRADE , KARNEGIJEVA 4, P.O. BOX 494, BELGRADE, YU-11000, YUGOSLAVIA
2. INSTITUTE OF GENERAL AND PHYSICS CHEMISTRY , BELGRADE, YU-11000, YUGOSLAVIA
3. DEPARTMENT OF ANALYTICAL CHEMISTRY, STATE TECHNOLOGICAL ACADEMY OF VORONEZH , PROSPECT REVOLUTION 19, VORONEZH, 394 000, RUSSIA