Influence of the Generator in-Growth Time on the Final Radiochemical Purity and Stability of ^99mTc Radiopharmaceuticals

Table 2

pH, ⁹⁹Mo, ¹⁰³Ru, and ¹³¹I amounts and radiochemical purities (mean ± standard deviation) of the evaluated generators’ elutions.

Type of generator	Type of elution	pH	^99Mo %	^103Ru %	^131I %	RCP %
Drytec-GE	1° eluate	6.0±0.3	(2.1±0.2)×10^−2	(1.9±0.2)×10^−6	(1.4±0.4)×10^−7	99.8±0.3
	36 h	6.0±0.4	(3.9±0.5)×10^−2	—		99.7±0.3
	48 h	6.1±0.3	(3.7±0.4)×10^−2	—		99.8±0.2
	72 h	6.0±0.2	(3.1±0.2)×10^−2	—		99.7±0.3
Elumatic III	1° eluate	6.2±0.1	(2.7±0.3)×10^−2	(1.7±0.5)×10^−7	(2.2±0.3)×10^−7	99.8±0.1
	36 h	6.2±0.3	(2.5±0.5)×10^−2	—		99.8±0.3
	48 h	6.2±0.4	(2.5±0.1)×10^−2	—		99.6±0.2
	72 h	6.1±0.2	(2.5±0.3)×10^−2	—		99.4±0.1
E.P.		4.8–8.0	<0.1%	<5 × 10^−3	<5 × 10^−3	≥95.0

E.P.: European pharmacopoeia; 36, 48, and 72 h indicate the time from the previous elution; the amount of ⁹⁹Mo represents the % of total radioactivity in the generators’ eluates determined with “rapid method”; ¹⁰³Ru (0.497 MeV) and ¹³¹I (0.365 MeV) are the most common gamma radionuclide detectable by gamma spectrometry, and in the table are reported the % of total radioactivity in the generators’ eluates.