Dear All: I will be very grateful if somebody can give me suggestions or references as how to extract water from alunite, K2SO4.Al2(SO4)3.4Al(OH)3, for D/H and 18O/16O analysis. I tried vacuum distillation at 550 degree C. Instead of pure water, I got sulfuric acid with very strong smell of SO2. Best regards. Dachun Zhang Global Geochemistry Corp. 6919 Eton Ave. Canoga Park, CA 91303