Microwave rapid extraction of free fatty acids from Zanthoxylum bungeanum Maxim and their HPLC fluorescence detection by pre-column derivatization

Free fatty acids (FFAs) in Zanthoxylum bungeanum Maxim were extracted by microwave-assisted extraction and derivatized using 2- (12-oxobenzobacridin-5 (12H) -yl) ethyl-4-toluenesulfonate (BAETS) as derivatization reagent.This method was proposed to detect 19 long-chain saturated and unsaturated FFA derivatives by HPLC fluorescence detection using pre-column derivatization.Microwave-assisted extract percentages almost reached 100% when FFAs were extracted at microwave power 700W, 70℃ and 10min using chloroform/methanol (1∶1, v∶v) .Good chromatographic separation was achieved using acidic acetonitrile/water as mobile phase on Eclipse XDB-C 8 column (4.6mm×150mm, 5μm) by gradient elution.On-line APCIMS identification was used for producing more accurate HPLC fluorescence quantitation.Fluorescence excitation and emission wavelengths for HPLC detection were 273nm and 505nm, respectively.The results indicated that microwave-assisted extraction was fast and efficient, and the developed analytical method had good linearity.Linear range was from 14.286 to 0.0139μmol/L, the lowest detection limits was 0.636nmol/L, the recovery was in the range of 87.60% ～106.59% .The established method was rapid, accurate, and highly sensitive, it can be used as standardized detection method for free fatty acids.