For me, I lose a substantial amount of product each time I aliquots, I guesstimate about 0.1-0.3ml total depending of how much liquid I start with.
I am not yet sure where it's all coming from, I suspect there's a bit left in each syringes and needles each time I swap them, even tho I purge them and use low-loss ones.
It seems like I'm losing a bit through evaporation and surface tension, I stopped using evacuated aliquots for this reason and switched to smaller ones, it's better but not perfect.
The filtration is also a place I may be losing some, so I pre-wet and (try to) air purge them too.
All in all, if we add all this, I lose some amount, it sucks I would like to lose nothing since it throws of the dosage and all, I try to take the loss into account, but not a very precise science.