Alkyl polyglycosides today represent the most important sugar surfactant. Nonionic sugar surfactants produced via different synthetic routes are mixtures of alkyl homologues, oligomers, anomers and isomers. Alkyl homologues and oligomers of alkyl mono- and diglucosides were separated by reversed-phase high-performance liquid chromatography (HPLC) with methanolwater as the mobile phase using a gradient elution. The gradient was optimized in respect to a simultaneous separation of alkyl glycosides according to their alkyl chain length and alkyl polyoxyethylene glucosides with regard to their length of the polyoxyethylene spacer. The separation of alkyl glycosides into ?- and ?-anomers was carried out by normal-phase HPLC with isooctaneethyl acetate (60:40, v/v)2-propanol in the gradient mode. Light scattering detection was used. Matrix-assisted laser desorption ionization time-of-flight mass spectra of alkyl glucosides and dodecyl glucosides with oxyethylene spacer groups are presented.
Mixed solvent systems for the critical liquid chromatography of polyisoprenes are investigated. Under critical solvent conditions, the energetic and entropic interactions between the polymer and the stationary phase cancel each other, the free energy of interaction approaches zero and the retention time is independent of the polymer chain length. Critical conditions for polyisoprene-silica gel have been established for a non-protic binary solvent mixture [i-octane-tetrahydrofuran (THF); critical composition at 0.88% (v/v) of THF] and a ternary system containing an acidic component [i-octane-[0.5% (v/v) acetic acid in methyl-tert.butylether (MTBE)]; critical composition at 0.65% (v/v) of the acetic acid-MTBE mixture].