We note that previous work on pure cholesterol samples prepared without water and without the complicating presence of salts, showed profile data of the molecule ion after losing the hydroxyl group [M-OH] + at the outermost surface and the molecular ion [M-H] + below it, consistent with an inward molecular orientation of the hydroxyl group. In this LNP system, we do not see an intense [M-H] + ion, most likely due to adduct formation from sodium present in the PBS. While these two systems are very different cannot to be compared directly, the observation of the different of different cholesterol fragments suggesting molecular orientation in a model pure crystalline system is consistent with our observation of molecular orientation of the larger PMG-PEG2k using GCIB etching in this LNP system, suggesting that the orientation of small molecules such as cholesterol may be detectable in some systems. separating molecules like the ionisable lipid from the particle core. Molecules will partition based on their molecular properties, such as charge state and hydrophilicities, as exhibited at the pH of particle formulation in the formation of this hydrophobic barrier layer. As the molecular assembly of LNPs contributes to the determination of LNP structure and thereby function, further experimentation systematically varying the pH of formulation could enable the assessment of this hydrophobic barrier and its impact on molecular distribution.