Determination of tocopherols in vegetable oils by CEC using methacrylate ester-based monolithic columns

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Tocopherols (Ts) are vital antioxidants found in vegetable oils.
• Accurate determination of Ts is crucial for quality control and detecting adulteration.
• Existing methods for Ts analysis can be time-consuming or lack sufficient resolution.

Purpose of the Study:

• To develop and optimize a capillary electrophoresis (CEC) method for the separation and determination of tocopherols (Ts) in vegetable oils.
• To evaluate the performance of methacrylate ester-based monolithic columns for Ts analysis.
• To demonstrate the application of the developed method for detecting olive oil adulteration.

Main Methods:

• Development of methacrylate ester-based monolithic columns for CEC.
• Optimization of monolithic column pore size using 1,4-butanediol during polymerization.
• Optimization of mobile phase composition (MeOH-aqueous buffer with tris(hydroxymethyl)aminomethane) for Ts separation.
• Validation of the method for sensitivity (LODs) and reproducibility (interday and column-to-column).

Main Results:

• Optimal pore size for monolithic columns achieved with 12 wt% 1,4-butanediol.
• Excellent resolution of tocopherols achieved within 10 minutes using a 99:1 v/v MeOH-aqueous buffer (pH 8.0).
• Low limits of detection (LODs) < 2.3 microg/mL and high reproducibility (better than 5.6% at 25 microg/mL).
• Successful separation of both tocopherols and tocotrienols (T(3)s) from grapeseed and palm oils using a 93:7 v/v MeOH-aqueous buffer.
• Demonstrated application in detecting olive oil adulteration.

Conclusions:

• The developed CEC method using monolithic columns provides a rapid, sensitive, and reproducible means for analyzing tocopherols and tocotrienols in vegetable oils.
• The method is suitable for routine analysis and has practical applications, such as identifying adulterated edible oils.