I get stuck on a calculation. I have an aqueous dispersion of a Fe3O4 sample at a 1mg/ml concentration. I want to do some measurements with this sample at different Fe concentrations (in mM).
How to obtain the above mentioned Fe concentrations (0.2, 0.4, 0.6, 0.8, and 1.0) in mM from the stock of Fe3O4 (1mg/ml).