*2.3. Dissolution Tests*

Three different dissolution procedures were performed with the two reactors, installed on E&Z and Trasis systems, on three different irradiated targets (Y, Cr, and Mo) for the production of <sup>89</sup>Zr, <sup>52</sup>Mn, and 99mTc, respectively.

Prior to each test, the sealing capability of the system was assessed to prevent possible losses of reactants during the dissolution. After passing the leakage test, the two synthe-

sizers were then used for dissolution experiments of irradiated target at the conditions reported in Table 2. All chemicals and reagents involved in the purification process were of analytical grade, unless otherwise specified. Hydrogen peroxide 30% *w/w* and HCl 37% ACS reagents were purchased from Merck (Darmstadt, Germany).


**Table 2.** Summary of the performed tests. Time refers to the total time which the process lasted.

<sup>1</sup> Room temperature.

All the dissolution steps were remotely controlled by the module's dedicated software. To evaluate the dissolution efficiency, the target coins were always weighed before and after dissolution. Once dissolution was completed, visual inspection, gamma spectrometry, and activity measurement of the target solutions were performed for each production run. Gamma spectrometric measurements were performed using a High-Purity Germanium (HPGe) detector (Sw GENIE II Canberra, Meriden, CT, USA). The efficiency calibration was carried out in the energy window 17 keV to 1923.1 keV for three different geometries (Eppendorf 1ml; vial 5ml; vial 1ml) by using a multi-peak certified liquid source (containing the reference radionuclides <sup>241</sup>Am, <sup>109</sup>Cd, <sup>139</sup>Ce, <sup>57</sup>Co, <sup>60</sup>Co, <sup>137</sup>Cs, <sup>113</sup>Sn, <sup>85</sup>Sr, <sup>88</sup>Y, and <sup>51</sup>Cr), with Genie 2000 software. Activity measurement was carried out with a Capintec, Inc. dose calibrator, model CRC-25PET, periodically subjected to a quality control program. An appropriate factor was set for each isotope measured.
