Determination of food grade antioxidants using microemulsion electrokinetic chromatography

Seven food grade antioxidants were resolved by microemulsion electrokinetic chromatography. The antioxidants included propyl gallate, octyl gallate, dodecyl gallate, butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone and -tocopherol. They were resolved in 11 min using a low pH microemulsion containing 20% propan-2-ol. Theoretical plates in the range 39 000-95 000 per length of column (38.5 cm) were recorded for the antioxidants. The LODs were calculated to be in the range 9-44 g/mL (30 s hydrostatic injection and a 50 m id capillary column). The method can also be used to simultaneously analyse for the synthetic preservatives sorbic acid, benzoic acid, salicylic acid and the parabens. The method was successfully applied to noodles for the determination of butylated hydroxytoluene and propyl gallate and to pharmaceutical supplement tablets for -tocopherol. The in-capillary concentration of butylated hydroxytoluene by sweeping was also demonstrated.