## 3 Results
### Effective Molar Activity and Radionuclide and Metals Impurities  
The EMA of the isolated \({}^{89}\)Zr-oxalate was experimentally determined by the DFO titration method and the purified combined fractions 1-2. In all isolated purified solution, the EMA of \({}^{89}\)Zr-oxalate for foil and pressed targets were found to be in the range of 51-329 GBq/umol and 39-156 GBq/umol, respectively (Table 2). It was noticed that EMA increased proportionally with increasing irradiation time (Table 2, entries 2 and 3), beam current, and the proton-beam energy deposited on the target (entries 2 to 5) to reach 329 \(\pm\) 69 GBq/umol (8892 \(\pm\) 1865 Ci/mmol) for the \({}^{89}\)Y-foil target, the highest EMA  
Figure 4: Recovered and residual \({}^{89}\)Zr activities in the purification module components (\(n\) = 7). value reported at this time to our knowledge. However, EMA decreased when increasing the target thickness and the amount of \({}^{89}\)Y irradiated (entries 5 and 6). The EMA values were, to some extent, almost similar at 15 MeV and 40 \(\upmu\)A while using 0.50-mm thick \({}^{89}\)Y-foil and pressed targets (Table 2, entries 7 and 11). In addition, it was noticed that EMA of the isolated \({}^{89}\)Zr-oxalate and recovery activity were higher in purified fractions 1 and 2 for both \({}^{89}\)Y-pressed target and \({}^{89}\)Y-foil (Table 3). To estimate the radionuclide purity of \({}^{89}\)Zr after purification, \(\gamma\)-ray spectroscopy was performed. Using \({}^{89}\)Y-foil as starting material, two peaks with high intensities at 511 and 911 keV were observed (Figure 5A). In addition, measurements were repeated after six months to allow for a complete decay of \({}^{89}\)Zr. Spectra of \(\gamma\)-ray showed no presence of \({}^{88}\)Zr (393 keV) and \({}^{88}\)Y (898 and 1836 keV) impurities [20] (Figure 5B) when the irradiation was done at 11.3 MeV. However, three peaks corresponding to \({}^{88}\)Zr (<0.001%) and \({}^{88}\)Y impurities were clearly observed on the \(\gamma\)-ray spectrum six-month post-purification of \({}^{89}\)Zr irradiated at 13.3 MeV (Figure 5C). As obtained with purified \({}^{89}\)Zr from \({}^{89}\)Y-foil, no impurities of \({}^{88}\)Zr and \({}^{88}\)Y were noted at six-month post-purification for \({}^{89}\)Zr that was produced at 11.3 MeV from \({}^{89}\)Y-pressed powder. Nevertheless, small intensity peaks corresponding to long half-life radiometals, such as Co-57 (122 keV, \(t_{1/2}\) = 271.79 d), Co-58 (511 keV, \(t_{1/2}\) = 70.86 d), and Co-56 (846 and 1238 keV, \(t_{1/2}\) = 77.7 d), were observed at this time point (Figure 5D). They probably originated from iron impurities in \({}^{89}\)Y-pressed powder (Table 1) via \({}^{58}\)Fe(p,n)\({}^{58}\)Co, \({}^{56}\)Fe(p,n)\({}^{56}\)Co, \({}^{57}\)Fe(p,n)\({}^{57}\)Co, and \({}^{58}\)Fe(p,2n)\({}^{57}\)Co reactions. In addition, the 1460 keV peak decayed from K-40 (\(t_{1/2}\) = 1.28 \(\times\) 10\({}^{9}\) y, 0.0117% neutral abundance) [21; 22; 23]. The metal impurities were quantified by ICP-MS for \({}^{89}\)Zr-oxalate fraction 2 samples that were produced by cyclotron, while using \({}^{89}\)Y-foil or pressed powder as starting materials (Table 4 and Table S1). Metallic impurities were below the general limit of 10 ppm for heavy metals in the US and Ph.Eur for both \({}^{89}\)Y-foil and pressed targets. Impurity metal concentrations, such as antimony, arsenic, barium, beryllium, bismuth, cadmium, chromium, cobalt, copper, lithium, magnesium, manganese, molybdenum, nickel, selenium, silver, strontium, thallium, tin, titanium, vanadium, and lead, were below the detection limit of <1.0 ppm in all analyzed samples.