Dear Ellie Major,

In my opinion, usually we need 5ml peripheral blood for 1ml mononuclear cells

How many cells in total or per µl do you need for your experiments? Then you can calculate how much peripheral blood you should start with.

Generally, 3 ml Ficoll-Hypaque per 10 ml blood/PBS mixture are used.

You may also want to have a look at the information here:

https://www.researchgate.net/post/Hello_Pleas_I_need_to_isolate_the_peripheral_blood_mono-nuclear_cells_called_buffy_coat_PBMC_MNC_from_blood_using_Ficoll_Is_there_any_protocol