Super-resolution imaging reveals resistance to mass transfer in functionalized stationary phases.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39951540.
- Also identified by DOI 10.1126/sciadv.ads0790 and PMC identifier 11827638.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Chemical separations are costly in terms of energy, time, and money. Separation methods are optimized with inefficient trial-and-error approaches that lack insight into the molecular dynamics that lead to the success or failure of a separation and, hence, ways to improve the process. We perform super-resolution imaging of fluorescent analytes in five different commercial liquid chromatography materials. Unexpectedly, we observe that chemical functionalization can block more than 50% of the material's porous interior, rendering it inaccessible to small-molecule analytes. Only in situ imaging unveils the inaccessibility when compared to the industry-accepted ex situ characterization methods. Selectively removing some of the functionalization with solvent restores pore access without substantially altering the single-molecule kinetics that underlie the separation and agree with bulk chromatography measurements. Our molecular results determine that commercial "fully porous" stationary phases are over-functionalized and provide an alternative avenue to characterize and direct separation material design from the bottom-up.