If it is salt free evaporation with N2 is a good way, id there is salt inside you would concentrate the salt too much which could cause problems in downstream processing. A good way would be ultrafiltration with e.g. 5 kDA tubes -> you spin it down to the desired volume
i did lyophilization.. but i got only film not powder.. my protein suspension contains phenol and cresol, ZnCl2, NaOH, HCl and water. But i want to remove every one of these additives.. anyone help me please