The Mn 2+ content of the MNPs was then varied by changing both the metallic precursor ratio added and the final volume. Two series of MnxFe3-xO4 MNPs were synthesized: A Series (large-scale synthesis), where the MNPs were prepared in 150 mL of BE, and B Series (small-scale synthesis) obtained using 50 mL of BE. Mn 2+ content in both series was tuned by changing the initial Fe(acac)3/Mn(acac)2 ratios, corresponding to a theoretical x value of 0.40, 0.75, and 1.0 (Table in the S.I.). In all cases, the Mn 2+ incorporated in the final MNP was much lower than the theoretical one (according to the amount of Mn 2+ added as initial precursors). This effect has already been described and could be attributed to a variety of factors, such as the different decomposition temperatures between the two precursors and/or the differences in the ionic radii between Mn 2+ and Fe 2+14, . In other cases, however, this effect has not been observed when using the same metallic precursors 8,3 or oleates . Nevertheless, in the latter, octadecene was used as the synthetic solvent instead of BE, and thus, a direct comparison cannot be drawn. As a common trend, higher initial metallic precursor concentration under both synthetic conditions resulted in higher Mn 2+ incorporation in the final nanostructure (Table ). This tendency, determined by ICP-OES, was further confirmed by EDX for samples belonging to A Series (Figure in the S.I.).