Production of L-[1-11C]valine by HPLC resolution.
Based on a recently developed analytical technique, preparative high-performance liquid chromatographic (HPLC) resolution of DL-[1-11C]valine has been achieved. A conventional reverse-phase HPLC column and a chiral mobile phase (aqueous solution of L-proline, cupric acetate, and sodium acetate) were used. The copper can be removed from the L-valine fraction by precipitation as the sulfide, and final purification by cation-exchange chromatography yields L-[1-11C]valine in a form that is acceptable for clinical positron tomographic studies. This purification method does not remove the L-proline introduced in the resolution process, but added L-proline did not affect the tissue distribution of L-[1-14C]valine in rats. We have produced up to 60 mCi of L-[1-11C]valine in an overall synthesis and resolution time of 50 min. This procedure should be adaptable to the rapid resolution of other C-11-labeled amino acid racemates.
D002250:Carbon Radioisotopes; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D007536:Isomerism; D007553:Isotope Labeling; D011392:Proline / Q000378:metabolism; D011829:Radiation Dosage; D013678:Technology, Pharmaceutical; D014018:Tissue Distribution; D014055:Tomography, Emission-Computed / Q000379:methods*; D014633:Valine / Q000302:isolation & purification* / Q000378:metabolism
D002250:Carbon Radioisotopes; D011392:Proline; D014633:Valine