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Single-Molecule Pycnometry and Shape Analysis of Ions in the Gas Phase
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DOI：10.1021/acs.analchem.3c00625.png)
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Abstract
En 中文
The analysis of ions and clusters by mobility-classifiedmass spectrometryprovides information on the mobility of analytes in the drift gasand the analyte mass. Mass equivalent and mobility equivalent diametersof globular analytes, such as ions, poly(ethylene glycol) (PEG), andionic liquid nanodroplets, can be correlated with good accuracy bythe Stokes-Millikan mobility model. A prerequisite to suchan analysis is, however, the assumption of a globular analyte shape,which then allows determination of material density for globular ions.We show that the analyte density can be evaluated with high precision,independent of any assumptions on the analyte shape, by careful analysisof analyte-PEG-cluster ions following the concept of classical pycnometry.In particular, the analyte is entrapped in a globular PEG-analytedroplet. Based on the now independently derived mobility diameterand volume equivalent diameter, it is possible to attribute two parameters,size and shape, to the analyte molecule. We demonstrate the approachfor lysozyme, cyano-cobalamin (vitamin B12), and glucose, which covertwo orders of magnitude in analyte mass (180 & BULL;& BULL;& BULL;14 300Da). The derived densities for these analytes are highly accurate,i.e., they deviate less than 1% from literature values. Our methodcan be applied to newly synthesized molecules, supramolecular assemblies,isolated biomolecules, and molecular clusters, where only minor amountsof materials are available. The obtained shape parameters of lysozymeand cyano-cobalamin agree well with the expected molecular shapes.Data evaluation relies only on locations of the species in the mass-mobilityplane and is in principle independent of any mobility theory. Ourapproach is thus robust with respect to experimental uncertaintiesand produces identical results irrespective of the type of mobilityclassification and drift gas.
Keywords:
MOBILITY ANALYSIS
CROSS-SECTIONS
X-RAY
MASS
WATER
LYSOZYME
CRYSTALS
VOLUME
NM
Journal
IF:
6.7
Papers:
4.7W
Citations:
15.9W