A new probe for tracking the presence of E141i food colorant

HPLC/APCI-MS was applied to the characterization of copper pyropheophytin a, the main chlorophyllic derivative present in E141i, a marketed copper chlorophyll mixture used legally for addition of green hues in food products. Exceptionally, its use is banned in Europe and America for fats and oils and consequently, the characterization of copper pyropheophytin a by HPLC/MS is critical for olive oil control adulteration and also essential for the detection of this colorant in colored foodstuffs. The MS2 of copper pyropheophytin a shows four fragment ions arising from the loss of phytadiene, a product ion corresponding to the loss of the complete propionic unit at C17, and product ions corresponding to the loss of phytol and additional methyl groups at D ring. This last fragmentation reaction means the description by first time of the opening of the D ring, showing a new fragmentation pathway where to fit product ions of other chlorophyll derivatives not explained up to now and being an ideal probe for tracking the use of colorant E141i in foods.