Scaled-up radiolabelling of DOTATATE with 68Ga eluted from a SnO 2-based 68Ge/ 68Ga generator

A scaled-up radiolabelling and improved post-labelling purification procedure for [68Ga]DOTATATE is reported, using a more than 1 year old SnO2-based 1850MBq68Ge/68Ga generator (initially double-loaded with 3700MBq68Ge) as a source of ionic68Ga. The elution method of choice comprised elution with 0.6M HCl in a single 4mL fraction, containing up to 95% of the total eluted68Ga activity. The unpurified fraction was directly used for labelling after pH adjustment with 2.5M sodium acetate. Labelling efficiencies were determined at 90-95°C at various reaction times and reaction volumes of up to 5.7mL, using either 30μg or 50μg DOTATATE. Only the latter amount resulted in consistently high labelling efficiency in excess of 95%. Post-labelling purification, carried out on Sep-Pak C18, showed that 50% ethanol in saline was a superior desorption eluant than 100% ethanol. The highest and most consistent decay-corrected radiochemical yields (89%) were obtained using 50μg DOTATATE and a 20min reaction time.