2.6.3. Radionuclidic Purity

Radionuclidic purity (RNP) is determined by γ-spectrometry using a HPGe detector calibrated using standard sources, coupled with a multichannel analyzer [50]. The coproduced short-lived 60,61,62,66,68,69Cu radioisotopes do not significantly affect the RNP of <sup>67</sup>Cu [5]. However, the coproduction of the longer-lived <sup>64</sup>Cu in most production routes is unavoidable and the <sup>64</sup>Cu/67Cu ratio is an important factor defining the quality of <sup>67</sup>Cu. Ohya et al. [50] determined the activities of <sup>61</sup>Cu, <sup>64</sup>Cu, <sup>67</sup>Cu, and <sup>65</sup>Zn considering the <sup>64</sup>Ni(α,p)67Cu reaction through the measurement of the following γ-lines, respectively: Eγ = 656.0 (10.8%), 1345.8 (0.473%), 184.6 (48.7%), and 1115.5 (50.60%) keV. Based on the analytical method proposed by Van So et al. [69], the activities of <sup>67</sup>Cu and <sup>67</sup>Ga can be evaluated from the measurements of their mixed signal in the γ-lines at 184.6 keV (48.7% for <sup>67</sup>Cu and 21.2% for <sup>67</sup>Ga), 209.0 keV (0.115% <sup>67</sup>Cu and 2.4% <sup>67</sup>Ga), 300.2 keV (0.797% <sup>67</sup>Cu and 16.8% <sup>67</sup>Ga), and 393.5 keV (0.22% <sup>67</sup>Cu and 4.68% <sup>67</sup>Ga) [63]. With this method, it is possible to infer the <sup>67</sup>Cu and <sup>67</sup>Ga activities without a radiochemical separation process. Similarly, Pupillo et al., proposed the method to correct for the residual Ga-activity in copper-solution [16] and Nigron et al., performed the measurement of the <sup>70</sup>Zn(d,x)67Cu cross section [23]. The presence of the following impurities can be determined in the <sup>67</sup>Cusolution considering the main radionuclides γ-lines: <sup>66</sup>Ga (1039 keV, 37%) <sup>58</sup>Co (810.8 keV, 99.45%), <sup>65</sup>Zn (1116.0 keV, 50.04%), <sup>57</sup>Ni (1377.6 keV, 81.7%), and <sup>105</sup>Ag (344.5 keV, 41.4%). It is important to remember that the impurity profile depends on the nuclear reaction route and on the specific irradiation conditions, in addition to the radiochemical processing of the target.
