2.5. Ultra performance liquid chromatography (UPLC-MS/MS) analysis of phenolic acids
Phenolic acid compounds including protocatechuic acid, 4-hydroxybenzoic acid, vanillic acid, caffeic acid, p-coumaric acid and ferulic acid in tissue cultured, acclimatized and wild Pelargonium sidoides plant extracts were quantified using UPLC-MS/MS as described by Gruz et al. (2008). Deuterium-labelled internal standards were added to the extraction solvent prior to plant material homogenization.