HPLC-MS/MS Determination of Residual Amount of 4-Chlorophenoxyaceticacid in Foodstuffs

HPLC-MS/MS was applied to the determination of residual amount of 4-chlorophenoxyacetic acid in foodstuffs. The sample was extracted with ethyl acetate and purified by passing through Waters Oasis MAX solid phase extraction column. The eluate was dissolved with 1 mL of mobile phase and used for HPLC-MS/MS determination, in which ZORBAX SB-C18 column (50 mm×2.1 mm, 3.5 μm) was used as chromatographic column, and a mixture of acetonitrile and 0.1% methane acid (in the ratio of 45 to 55 by vol.) was used as mobile phase; negative electrospray ionization as well as multiple reaction monitoring mode was used in the detection. Linear relationship between values of peak area and mass concentration of 4-chlorophenoxyaceticacid was obtained in the range within 500 μg·L-1, with detection limit (3S/N) of 1 μg·kg-1. Tests for recovery and precision were made by standard addition method at 3 different concentration levels, values of recovery found were in the range of 70.5%-99.8%, and values of RSD′s (n=10) were in the range of 4.6%-10.6%.