Determination of Vitamin E in Olive Oil Using the Agilent 1260 Infinity Analytical SFC System

Importance of the Topic

Vitamin E compounds such as tocopherols and tocotrienols play a key role in human health due to their antioxidant properties. Olive oil, particularly extra virgin varieties, is a principal dietary source of these fat-soluble vitamins. Reliable quantification of individual isomers is essential for product quality control, authenticity verification and nutritional labelling in the food industry.

Aims and Overview

This application study presents a rapid, high-resolution method for the separation and quantification of eight vitamin E isomers in olive oil using supercritical fluid chromatography (SFC) on the Agilent 1260 Infinity Analytical SFC System. Calibration was performed over six concentration levels, and limits of detection and quantification were established. A real virgin olive oil sample was analyzed to demonstrate method applicability.

Methodology and Instrumentation

The method employs supercritical CO₂ with ethanol modifier under a near-isocratic gradient (3 % to 4.5 % ethanol) at 4.5 mL/min, 210 bar backpressure and 50 °C column temperature. Key instrumentation and materials include:

• Agilent 1260 Infinity Analytical SFC System with SFC Control Module, Binary Pump, High-Performance Degasser, Standard Autosampler and DAD detector
• Agilent ZORBAX NH2 column, 4.6×150 mm, 5 µm
• OpenLAB CDS ChemStation software
• Mixed tocopherol/tocotrienol standards in hexane
• Virgin olive oil sample diluted to 100 mg/mL in hexane

Key Results and Discussion

The optimized SFC method achieved baseline separation of all four tocopherol and four tocotrienol isomers within a 6-minute runtime. Calibration curves over six levels (14 to 463 µg/mL) showed excellent linearity (R² > 0.999). Limits of quantification were typically below 23 µg/mL, and detection limits under 7 µg/mL. Precision was high, with retention time RSDs below 0.3 % and peak area RSDs below 6 %. An olive oil sample analysis yielded 184.8 mg/kg of α-tocopherol as the dominant isomer and a minor trace of γ-tocopherol.

Benefits and Practical Applications

The SFC approach offers significant advantages over traditional normal-phase LC methods: rapid analysis, reduced consumption of harmful organic solvents, improved resolution for isomeric compounds and robust precision. This makes it well suited for routine QA/QC testing in food and agricultural laboratories.

Future Trends and Opportunities

Potential developments include coupling SFC with mass spectrometry for enhanced compound identification, extending the method to other fat-soluble vitamins and bioactives, automating sample preparation, and applying SFC workflows to a broader range of food matrices and quality assurance programs.

Conclusion

The Agilent 1260 Infinity Analytical SFC System provides a fast, sensitive and reliable platform for the quantitative determination of vitamin E isomers in olive oil, supporting quality control and nutritional analysis needs in the food industry.

Reference

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• Aparicio, R.; Aparicio-Ruíz, R. Authentication of vegetable oils by chromatographic techniques, J. Chromatogr. A 2000, 881, 93–104
• Cort, R. et al. Stability of alpha- and gamma-tocopherol: Fe3+ and Cu2+ interactions, J. Food Sci. 1978, 43, 797–798