Dear Adauto,

NH4-sulfate standards are distributed by the IAEA in Vienna. Ask
Manfred Groening for the supply modi.

Good luck
Michael

*********************************************************************
Dr. Michael E. Boettcher
Institute of Chemistry and Biology of the Marine Environment (ICBM)
Carl von Ossietzky University
P.O. Box 2503
D-26111 Oldenburg
FRG
**********************************************************************