Flow ram radio hplc detector

⁶⁴Cu (_t1/2= 12.7 h, β⁺=17%, β^-=39%, EC=43%, E_max=0.656 MeV) was produced by a (p,n) reaction on enriched ⁶⁴Ni on a CS-15 biomedical cyclotron (Cyclotron Corporation, Berkeley, CA) at Mallinckrodt Institute of Radiology, Washington University School of Medicine and purified on an automated system using standard procedures ^{58 ,59} . A stock solution of ⁶⁴Cu in 0.05 M HCl was diluted in 0.1 M ammonium acetate (NH₄OAc) buffer solution (pH 7) for radiolabeling purposes. A typical reaction involves using 74 – 111 MBq (2 -3 mCi) of ⁶⁴Cu added to 20 μL of Ybt (5 nanomoles) and 0.1 M NH₄OAc buffer to bring the reaction volume to 100 μL. The reaction mixture was incubated on a mixer with 800 rpm agitation at 37 °C for 1 hour. Labeling efficiency and radiochemical purity were determined using radio-HPLC (Agilent 1200 system with a Flow-RAM radio-HPLC detector) on a C18 column (Kinetex, Phenomenex). The mobile phase consisted of water (A) and acetonitrile (B) with a gradient of 0 – 100 % B over 10 min using a flow rate of 1 mL/min. The retention time of ⁶⁴Cu(II)-Ybt was 6.1 min and a radiochemical yield of greater than 99% was achieved and used without further purification.