Quality Analysis of Virgin Olive Oils – Part 4

Importance of the Topic

Virgin olive oil is valued for its health-promoting antioxidants, notably vitamin E isomers (tocopherols and tocotrienols). Precise quantitation of these compounds is critical for nutritional assessment, authenticity verification and quality control in food analysis.

Objectives and Study Overview

This study evaluated the performance of normal phase liquid chromatography with fluorescence detection on the Agilent 1260 Infinity Bio-inert Quaternary LC system to separate and quantify eight vitamin E isomers. Key objectives included comparing bio-inert and stainless steel systems in terms of retention time and area precision, establishing calibration metrics (linearity, LOD, LOQ), and profiling vitamin E content in nine olive oil samples.

Methodology and Instrumentation

• Instrumentation: Agilent 1260 Infinity Bio-inert Quaternary Pump, Bio-inert Autosampler, Thermostat and Column Compartment, Fluorescence Detector; Agilent LiChrospher DIOL column (4×250 mm, 5 µm).
• Solvents: LC-grade n-heptane and methyl tert-butyl ether.
• Chromatography: Isocratic NP-UHPLC (tBME:heptane 5:95 v/v), 1 mL/min, column at 35 °C, sample cooled at 4 °C, injection 10 µL.
• Detection: Ex 298 nm, Em 330 nm fluorescence.

Main Results and Discussion

• Retention and area precision: Bio-inert system achieved RSD < 0.07 % for retention times (vs ~ 0.7 % stainless steel) and 3–10× improved peak area precision.
• Linearity and sensitivity: Excellent linearity for all isomers (r > 0.9998); LODs and LOQs in the low µg/mL range.
• Sample analysis: Nine olive oil samples showed a-tocopherol levels from 100 to 390 mg/kg, with minor tocopherol and tocotrienol isoforms consistent across virgin and partly refined oils.

Benefits and Practical Applications

This robust NP-HPLC method provides highly reproducible and sensitive quantitation of vitamin E isomers, supporting reliable quality control, authenticity testing and nutritional profiling of vegetable oils in research, industrial and regulatory environments.

Future Trends and Potential Applications

• Expansion to other lipid matrices and complex food samples.
• Integration with UHPLC-MS for structural confirmation and broader analyte coverage.
• Investigation of oxidative degradation products and shelf-life markers.
• Adoption of high-throughput and automated workflows linked to digital laboratory information management systems.
• Use of greener solvents and sustainable chromatography practices.
• Application of AI-driven data analysis for pattern recognition and fraud detection.

Conclusion

The Agilent 1260 Infinity Bio-inert Quaternary LC system with normal phase fluorescence detection delivers superior precision, sensitivity and reliability for vitamin E isomer analysis in olive oil. Its performance advantages make it a recommended tool for comprehensive vitamin E profiling and quality assurance in food analysis.

References

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2. Schneider S. Quality Analysis of Virgin Olive Oils – Part 1. Agilent Application Note 5991-1894EN. 2013.
3. Schneider S. Quality Analysis of Virgin Olive Oils – Part 2. Agilent Application Note 5991-1985EN. 2013.
4. Schneider S. Quality Analysis of Virgin Olive Oils – Part 3. Agilent Application Note 5991-1896EN. 2013.
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