Essentially qualitative and quantitative analysis of components. Liquid chromatography covers components such as vitamins, peptides, lipids and secondary metabolites such as phenolics. Gas chromatography is used for volatile organic compounds and readily applies to the flavour component, e.g terpenes, aldehydes, alkanes and such; less volatile compounds such as fatty acids or amino acids are also amenable to GC after derivatisation.
Both methods record profiles of constituent components, which can be used to check quality, provenance and action, e.g. chemical phylogeny uses secondary metabolites in phylogeny of herbs.
Carsten Muller has given a very comphrehensive review on the application. LC and GC can also provide chemometric multivariate data modelling for authentication of herbal products.