Bioconcentration mechanism of selenium by a coccolithophorid, Emiliania huxleyi.
Plant Cell Physiol. 2004 Oct;45(10):1434-41.
http://pcp.oxfordjournals.org/cgi/content/full/45/10/1434#SEC4These guys obtained [75Se]selenite (H2SeO3 in 0.1 M HCl, 111 MBq ml1, 4,847 GBq g1 from Isotope Products Laboratories, Burbank, CA, U.S.A.
I know that although Amersham used to sell sodium 75Se selenite they have now discontinuted it and don't have a replacement product.