Small-scale two-dimensional liquid chromatography for a preparative re-purification of a highly labile tritium-labeled compound.

Tritium-labeled compounds are generally less stable than their non-labeled counterparts. This requires storage at low temperatures, a constant workflow of quality checks, and subsequent re-purifications. As the amount of tritium-labeled material is typically purified in the μg range, repeated injections on analytical-scale ultra high-performance liquid chromatography systems can provide high-resolution re-purification results. Yet, degradants can be undesirably included in the compound isolation because the amount of decomposition can vary dramatically depending on the structure. We report a case of a sensitive molecule that could not be isolated in pure form even though the chromatographic separation was successful. In this case, the use of a small-scale two-dimensional preparative liquid chromatography approach with a direct transfer interface to a second (trapping) column resulted in a highly pure compound (>98% radiochemical purity). This approach combines high chromatographic resolution, accurate control over the re-purification process, minimal sample manipulation, and higher overall safety for the handling of radioactive samples.