1. Food and Environmental Protection Laboratory, Joint FAO/IAEA Division of Nuclear Applications in Food and Agriculture, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Wagramerstrasse 5, A-1400 Vienna, Austria
2. Atomic Energy Commission of Syria, 17th Nissan Street, Damascus, Syria
3. Group for the Analysis of Trace Compounds (GACT), Facultad de Quimica, Universidad de la Republica, Avda. General Flores 2124, 11800 Montevideo, Uruguay