2.3. Thermogravimetric Analysis

The thermogravimetric analysis (TGA) of the MNMs was performed to quantify the adsorbed water content and a possible organic coating using a STA 449 F3 Jupiter instrument (Netzsch-Gerätebau, Selb, Germany). The TGA was performed according the NANoREG standard operating procedure for TGA [44]. The TGA was carried out in an oxygen atmosphere (air) to insure complete oxidation of the organic compounds. The temperature program for all samples was heating from 25 °C to 50 °C at 10 °C/min and hold for 1 min, then heating to 100 °C at 2.5 °C/min and hold for 10 min, then heating to 800 °C at 2.5 °C/min and hold for 1 min. The sample holders (crucibles) used for the TGA measurements were made of alumina (Al₂O₃) and had a volume of 3.4 mL. Sample masses were 10–60 mg and no samples were conditioned to equilibrate with known air humidity. Data was corrected for buoyancy. TGA was performed in triplicates.