High Molecular Weight Compounds

Gas chromatography (GC) is a well established method in the analysis of volatile low molecular weight compounds in food. This chapter outlines the possibilities for the analysis of such compounds by capillary gas chromatography (HRGC). The sampling of high molecular weight compounds requires careful attention in order to avoid quantitative sample losses. The direct analysis of extremely high molecular weight compounds such as proteins and polysaccharides by GC is impossible. In pyrolysis, high molecular weight compounds to be analyzed are thermally fragmented in an inert atmosphere to form products of lower molecular weight and higher volatility. Triglycerides containing higher molecular weight fatty acid groups such as stearic or oleic acid belong to the least volatile compounds in food which have been analyzed directly by gas chromatography. When compared with high-performance liquid chromatography, a method often used in the analysis of such compounds, HRGC offers more separation power and, using short capillary columns, a faster analysis time.

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