Continuous-flow determination of natural and synthetic antioxidants in foods by gas chromatography

A simple, rapid continuous-flow method with gas chromatographic detection for the simultaneous determination of natural and synthetic antioxidants (α-tocopherol, α-tocopheryl acetate, 2,6-di-tert-butyl-p-hydroxytoluene, tert-butyl-4-hydroxyanisole and tert-butylhydroquinone) is proposed. A solid-phase extractor is coupled to the flow system to isolate antioxidants from the sample matrix. During extraction, analytes are released from ca. 70% of the triglycerides present in fats and oils by using XAD-7 sorbent; after selective elution with 400 μl of 2-propanol, only ca. 0.7–0.8% of total triglycerides originally present in the sample remain in the final extract. XAD-7 adsorbs 70–95% of the antioxidants except BHT of which only ca. 30% is adsorbed. The proposed method is considered an effective alternative to earlier procedures.