HPLC Determination of 5 Anti-oxidants in Edible Vegetable Oil

Five synthetic anti-oxidants preferentially added to edible vegetable oil, namely propylgallate, tert-butylhydroquinone, tert-butylhydroxyanisole, octyl gallate and 2,6-di-t-butyl-p-hydroxytoluene, were determined by HPLC. The oil sample (1.000 g) was extracted twice with CH3OH (5 mL+5 mL) in a stoppered centrifuge tube by centrifuging for 10 min. The supernatant was transferred to a 25 mL glass tube which was kept at 4 ℃ to solidify and separate residual fats. The supernatant was taken, evaporated and made up to 10.0 mL with methanol. The solution (5 μL) was introduced for HPLC analysis by separation on the ZORBAX SB-C18 column (30 ℃) with gradient elution (flow rate: 1.0 mL·min-1) using mixtures of (A) methanol and (B) HOAc+H2O (1+99) in various proportions as mobile phase. UV detection with DAD at 280 nm was adopted in the determination. Detection limits (3S/N) found for the 5 antioxidants were 0.10, 0.34, 0.32, 0.14, 0.57 mg·kg-1 respectively. Recovery and precision were tested at 3 concentration levels (200, 500, 1 000 mg·kg-1), giving results of recovery ranged from 90.5% to 102.0%, and RSD′s (n=6) ranged from 0.02% to 1.35%.