Sources of carbon which decrease the specific activity of [11C]CH3I synthesized by the single pass I2 method

The sources of carbon, which decrease the specific activity of [11C]Methyl iodide [11C]CH3I synthesized by the single pass I2 method were, determined. Some organic solvents (acetone, CH3OH and THF etc.) and non-volatile oils (silicone oil and paraffin) could react with the I2 vapor to yield the non-radioactive CH3I in the heated quartz tube, which decreased the specific activity of [11C]CH3I significantly.