[derefr]

My understanding was that HPLC was just a way to do gaseous-diffusion enrichment (i.e. "standard chromatography") without the really long tubes. From the article:

> In standard chromatography, substances having different chemical characteristics are separated by making them run a kind of gauntlet—an obstacle course that blocks the passage of one thing more than the other. HPLC works by using a pumped solvent (hence the term “high pressure”) to strip off the laid-down film of carbon fullerenes in such a way that the desired molecules—the fullerenes encasing nitrogen—are carried away preferentially.

My interpretation of that statement is that HPLC uses a solvent that manages to detach the slightly lighter (and/or less electrostatically-attracted-to-the-film) molecule first, giving it a head start down the diffusion tube, letting the tubes be really short, and thus giving you a tabletop device instead of capital equipment in a dedicated facility.

Maybe HPLC of N@C60 really leans on that differential-electrostatic-attraction property, but it seems like the process would still work to separate isotopes that differ only by molecular weight.

I'm not a chemist of any sort, though, so I'd be glad to "get schooled" here.