A simultaneous FT-Raman–DSC (SRD) study of polymorphism in sn-1,3-distearoyl-2-oleoylglycerol (SOS)

Abstract

The simultaneous FT-Raman–differential scanning calorimetry (SRD) technique is described, which allows FT-Raman spectra to be collected from thermally sensitive samples with a very low power density at the sample surface, immediately followed by an in situ DSC melting curve. This gives unambiguous characterisation of samples which are thermally sensitive or which could be structurally transformed by an incident high power density laser beam. In the current work, SRD has been applied to a study of the structural polymorphs of the triglyceride 1,3-distearoyl-2-oleoylglycerol (SOS). SRD analysis shows DSC heating curves with onset melting points and features identifying the polymorphs produced as α, γ, β′, β2 and β1, conforming well to literature thermal behaviour. Interpretation of the corresponding Raman spectra for these polymorphs provides confirmation of existing structural models in the literature based on other analytical techniques.