*4.10. Stability, Serum Proteins Binding and Lipophilicity Studies*

The stability of [111In]In-IP-001 solutions (0.5 mL, 10 nmol, 18 MBq) was assessed by means of radio-TLC or RP-HPLC at various temperatures (4, 24, and 37 ◦C) and in the presence of different media up to 120 h after preparation. The studies were performed by incubating the radiotracer with (i) a 0.9% NaCl solution at a 9:1 ratio, (ii) a 0.1 M HEPES solution at a 9:1 ratio, (iii) a 0.1 M EDTA solution at 9:1 and 1:1 ratios, (iv) human serum (HS) at a 9:1 ratio, and (v) HB at a 1:1 ratio. After TLC analysis, samples incubated with HB were centrifuged at 3000 rpm for 10 min to precipitate blood cells, and 200 µL of a MeCN/H2O/TFA 50/45/5 *v*/*v*/*v* solution was added to 400 µL of the supernatant. After another centrifugation under the same conditions, the supernatant was discarded and the residual radioactivity due to the proteins bound fraction was measured in a dose calibrator. Lipophilicity calculation were performed in octanol–water with the shaking flask method, as already described elsewhere [13]. All experiments were performed in triplicate.
