HPLC-MS/MS Determination of Phenylethyl Caffeate in Propolis

HPLC-MS/MS was applied to the determination of phenylethyl caffeate in propolis. The propolis sample was extracted ultrasonically with methanol. Sepax GP-C18 column was used as stationary phase, and a mixture of methanol and 5 mmol·L-1 NH4OAc solution, (both of which containing 0.5% by vol. of formic acid), mixed in the volumic ratio of 80 to 20 was used as mobile phase in the separation. ESI- as well as multi-reaction monitoring was adopted in MS/MS. Linear relationship between values of peak area and mass concentration of phenylethyl caffeate was kept in the range of 0.2-500 μg·L-1, with detection limit (3S/N) of 0.003 g·kg-1. Tests for recovery were made by addition of standard solutions at concentration levels of 0.01, 0.1, 1.0 g·kg-1, values of recovery found were in the range of 73.0%-98.1% with RSD′s (n=6) no more than 3.5%.