HPLC Determination of Antioxidants in Roasted Seeds and Nuts with Solid Phase Extraction

A method of HPLC for determination of synthetic and natural antioxidants,i.e.BHA,BHT,TBHQ,PG,tea polyphenol,licorice root antioxidant,rosemary extract and etc.,in roasted seeds and nuts was proposed.The samples were extracted with a mixture of methanol-isopropanol-acetonitrile (2+1+2),and antioxidants in the extract were separated and enriched by solid phase extraction (SPE) on C18 column.The SPE column was eluted with methanol,and the eluate obtained was evaporated to dryness by N2-blowing at 50 ℃ and made up to 1.0 mL.An aliquot of 1.0 μL was used for HPLC determination.C18 reversed-phase column was used as the stationary phase and mixtures of acetonitrile and trifluoroacetic acid-water solution (0.05+99.95) in different ratios were used as the mobile phase in gradient elution.UV detection at 250 nm for glycyrrhizic acid and 280 nm for the other antioxidants was adopted.Linear relationships of antioxidants were found in definite ranges,with values of limit of determination (10S/N) in the range of 0.1 to 1.0 mg·kg-1.On the base of blank samples of fried peanut,tests for recovery were made by standard addition method.Values of recovery and RSD′s (n=6) found were in the range of 83.6%-106.0% and 1.3%-3.9% respectively.