Dear Brian,
we analysed freeze-dried jellyfish for C and N isotope compositions. 
Somewhere between 3 an 6% of jellyfish consists of collagen and that's 
mostly what remains as dry matter. After freeze drying, a lot of salt 
will remain in your sample, so it is better to remove salt first by 
dialysis. However, the presence of salt didn't really affect the delta 
values, the differences were within the analytical error for both C and N.

With kind regards,
Sonja

-- 
Doc. dr. Sonja Lojen
Odsek za znanosti o okolju - Department of Environmental Sciences
Institut J. Stefan - J. Stefan Institute
Jamova 39
1000 Ljubljana
Slovenia

Tel.: (+386 1) 5885 393
Fax: (+386 1) 5885 346