A fast and reliable ultrahigh-performance liquid chromatography method to assess the fate of chlorophylls in teas and processed vegetable foodstuff

A total of 48 chlorophylls and derivatives were identified and successfully determined in tea and processed vegetable and fruit foodstuff by UHPLC with photodiode-array and mass spectrometry detection. The method allowed the proper separation of chlorophyll derivatives resulting from demetallation, dephytilation, decarbomethoxylation, epimerisation and copperisation. The method was performed in less than 12 min, using an optimised ternary gradient (MeOH, iPrOH, MeCN and H₂O with 10 mM of ammonium acetate) on an ACQUITY HSS T3 column. Mass spectrometry, applying both ESI and APCI ionization sources, was used for identification purposes. The method was applied to evaluate the degree of processing in teas of different origin and quality. It allowed differentiation between supermarket own-brand tea bags and teas sold by specialised shops. Pheophytins, pheophorbides and pyro derivatives were found mainly in processed green vegetable and fruit products thereof. However, chlorophyll-derived food colorants, such as Cu-chlorophyllins, Cu-pheophytins, Cu-pyropheophytins, Cu-pheophorbides and Cu-pyropheophorbides, were also detected in several products.