Fig 1.
Structure of 2-hydroxypropyl-β-cyclodextrin (HPβCD) where R = H or CH2-CHOH-CH3.
There are 21 (red) hydroxyl groups on βCD which are potential substitution sites for the condensation reaction with propylene oxide to yield various species of HPβCD with different degrees of substitution depending upon how many sites are substituted.
Fig 2.
Ion mobility false color representations (“heat map”) of VTS-270 and Trappsol Cyclo.
Ion mobility drift time (msec) is shown on the x axis and m/z on the y axis. Heat map intensities are shown with colors ranging from lowest intensity in blue to highest intensity in red. Materials were infused under the same preparation conditions and at the same concentration of HPβCD. Trappsol Cyclo exhibits greater chemical heterogeneity than VTS-270 as observed by the more complex overall heat map and the m/z singly charged trend line (long oval-shaped area), the region labeled “higher order complexes,” and the region corresponding to triply charged dimers.
Fig 3.
Mass spectra of a portion of the heat maps of VTS-270 and Trappsol Cyclo showing the m/z region dominated by singly charged NH4+ adduct ions.
The spectra represent the areas in Fig 1 that are labeled “Region 1.” See text for detailed description of the spectra. The numbers above the most intense ions of each spectrum show the degrees of substitution of the ammonium adduct for that species (eg, nominal mass 1384, corresponding to the ammonium adduct of a degree of substitution equal to 4). The spectra show clear differences between VTS-270 and Trappsol Cyclo in the distributions of ion intensities corresponding to the degrees of substitution, with Trappsol Cyclo having a greater range and higher degrees of substitution.
Fig 4.
Mass spectra of a portion of the heat maps of VTS-270 and Trappsol Cyclo showing the m/z region dominated by triply charged dimeric ions.
Ions A = [DSn +2NH4 +H]+3 and Ions B = [DSn+DSn-1+2NH4+H]+3. See text for detailed description of the spectra. The spectra show clear differences with substantial intensity of triply charged dimers for Trappsol Cyclo but not for VTS-270.
Fig 5.
Fraction of dimers as a function of the degree of substitution.
Fractional intensity of homodimer ions, relative to total hydroxypropyl-beta-cyclodextrin (HPβCD) ion signal, plotted as a function of the degree of substitution (A); fractional intensity of heterodimer ions, relative to total HPβCD ion signal, plotted as a function of the degree of substitution (B). The fractional intensity of ions as heterodimers and homodimers is greater with Trappsol Cyclo (red circles) than with VTS-270 (green triangles).
Table 1.
Ions as [M+H]+.
Table 2.
Ions as [M+NH4]+.
Table 3.
Ions as [M2+H + NH4]+2.
Table 4.
Ions as [M2 + 2NH4]+2.
Table 5.
Ions as [Mn + M(n-1) + H+ NH4]+2.
Table 6.
Ions as [Mn + M(n-1) + 2NH4]+2.