An LC/MS/MS Method for the Analysis of Furocoumarins in Citrus Oil

摘要

Furocoumarins are secondary plant metabolites commonly found in the families Umbelliferae and Rutaceae. The basic members of this class of compounds are psoralen and angelicin. Researchers have shown particular interest in alkoxy analogues of psoralen; particularly at the 5- and 8-positions. Bergapten (5-methoxypsoralen) and xanthotoxin (8-methoxypsoralen) have been found to be effective in the treatment of the skin diseases psoriasis and vitiligo when combined with the phototherapy technique, PUVA. A mode of action is thought to be mono-adduct formation with DNA but formation of di-adducts, leading to cross-linked DNA and potential carcinogenic side effects, is also a possibility. In response to this, the International Fragrance Association (IFRA) and the European Commission have agreed to ban the use of furocoumarins in cosmetic products except when they are part of natural essences. When present as the result of natural essences, the total furocoumarin concentration cannot exceed 5 ppm based on the analysis of seven marker furocoumarins. To ensure compliance, an LC/MS/MS method using electrospray ionization was developed for the analysis of the seven marker furocoumarins plus seven other furocoumarins. Various aspects of method development are discussed as well as conclusions from the analysis of citrus oils.