Metabolic profiling of β-cryptoxanthin and its fatty acid esters by supercritical fluid chromatography coupled with triple quadrupole mass spectrometry

In this study, a high-throughput and high-sensitivity profiling system for β-cryptoxanthin (βCX) and β-cryptoxanthin fatty acid ester (βCXFA) was constructed by supercritical fluid chromatography (SFC) coupled with triple quadrupole mass spectrometry (QqQMS). βCX and nine βCXFAs were successfully separated within 20 min using a column packed with octadecylsilyl-bonded silica particles. The limit of detection was 540 fmol for the free form and 32-130 fmol for the esterified forms. These results demonstrate that both the throughput and the sensitivity of this SFC-QqQMS system are considerably higher than those of conventional methods. When this system was applied for the analysis of Citrus unshiu, βCX and five βCXFAs were directly detected with much simpler sample pre-preparation. The analysis of other citrus fruits indicated that the βCXFA profiles varied with their breed variety. Furthermore, gas chromatography-mass spectrometry was used to analyze total fatty acid profiles in C. unshiu, and the results revealed that the profiles of fatty acids located in βCXFA were distinct. This is the first report on the analysis of βCX and its fatty acid derivatives by SFC-QqQMS. The profiling system developed in this study will be a powerful tool for investigating xanthophyll fatty acid esters.