I am planning a sampling of Mugil cephalus and I am going to sample blood to get the plasma. I have already done this sampling using syringes internally wet with sodium heparin. The method I used was to wash the walls of the syringes with liquid heparin. My questions are: how much heparin I need (ml) to get the blood from about 100 animals? are there any particul characteristcs required for the heparin (e.g. UI)? thanks