GC-MS in Quantification and Characterization of Phytoconstituents of Herbal Extracts: A Review

Gas Chromatography Mass Spectrometry (GC-MS) is an advanced hyphenated analytical technique used for separation, identification and quantification of mixture of compounds. GC-MS has a vital role in phytochemical fingerprinting of extracts and volatile oils. GC-MS is applicable for the analysis of low molecular weight, thermally stable volatile compounds. It is often used in drug detection, and is widely used in food industry to detect pesticides, contaminants, in pharmaceutical industry to detect impurities and residual solvent analysis, in testing environmental volatile pollutants, flavor and fragrances testing. Liquid, gaseous or solid samples can be detected by GC-MS method. The liquid or solid sample is first introduced into the column and the sample gets converted to gas. In gas chromatograph, the vaporized sample is introduced into gaseous phase and the components are separated using a capillary column coated with a stationary (liquid or solid) phase. Inert carrier gases such as helium, hydrogen or nitrogen are used as mobile phase in GC-MS. As the compound mixtures are separated, each component is eluted from the column at a various retention time based on its boiling point and polarity. The elution time is referred to as a compound’s retention time. Sample extracts containing hundreds of compounds or complex mixtures can be analyzed without isolating by GC-MS. MS detector gives better resolution in qualitative and quantitative analysis of samples. In this chapter, various GC-MS methods reported in characterization and quantification of phytochemicals of volatile oils and plant extracts were critically analyzed and discussed along with different ionization methods involved in GC-MS estimations.