Quantitative determination of straight and cyclic hydrocarbons in crystallized permethylated-beta-cyclodextrin inclusion complexes by static headspace-gas chromatography

Static headspace-gas chromatography (HS-GC) method is used for determinatio n of the stoichiometry of crystalline inclusion complexes of heptakis (2,3, 6-tri-Omethyl)-beta -cyclodextrin (TRIMEB) with methylcyclohexane, pentane, cyclohexane, hexane, (-)alpha -pinene, and (+/-)-alpha -pinene. The 'Full Evaporation Technique' (FET) with Multiple Headspace Extraction (MHE) measu rements is realized in a straightforward manner on the solid material; this appears to be the most convenient method for quantitative determination of the guest/host ratio. As an interesting alternative, the 'solution approac h' (sample dissolved in the solvent) is also performed by a single extracti on with ethanol as solvent, which is sufficiently polar to dissociate these complexes. TRIMEB forms stable 1:1 complexes with cycloalkanes or cycloalk enes at room temperature and normal pressure. In contrast, the stoichiometr y with n-alkane is different from ratio of 1:1 because this solid shows eff lorescent behavior under the same conditions.