Solvated thermal analysis fractionation

Temperature-risiag elution fractionation (tref) is a technique for obtaining fractions based on short-chain branch content versus molecular weight (96). On account of the more than four days of sample preparation required, stepwise isothermal segregation (97) and solvated thermal analysis fractionation (98) techniques usiag variatioas of differeatial scanning calorimetry (dsc) techniques have been developed. 

Costeux etal. [97] developed a model to predict the distribution of the longest ethylene sequence in mLLDPE, and Anantawaraskul etal [98] proposed a model for the CCD of multicomponent copolymers. Westphal et al. [99] compared DSC and TREF and showed how additional information can be provided by dynamic mechanical analysis (DMA). Another technique closely related to TREF is solvated thermal analysis fractionation (STAF), which makes use of a DSC apparatus [100]. 

On-line SFE coupled to GC or SFC, according to the thermal stability of the analytes, are both very competitive with classical methods of analysis in terms of sensitivity and analysis time. Since all of the extracted analytes are transferred to the GC system, much higher method sensitivities can be obtained. Several modes of operation are possible utilising on-line SFE-GC, including quantitative extraction of all analytes from a sample matrix quantitative extraction and concentration of trace analytes selective extractions at various solvating powers to obtain specific fractions and periodic sampling (multiple-step extractions) of the effluent at various pressures for qualitative characterisation of the sample matrix. 

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