Determination of ethoxyquin in feeds by liquid chromatography: collaborative study

Area of Science:

• Analytical Chemistry
• Food Science
• Animal Nutrition

Background:

• Ethoxyquin is a widely used chemical antioxidant in animal feeds, fats, and oils.
• Accurate quantification of ethoxyquin is crucial for ensuring feed safety and regulatory compliance.

Purpose of the Study:

• To develop and validate a reliable liquid chromatographic (LC) method for determining ethoxyquin concentrations in animal feed matrices.
• To assess the method's performance through a collaborative study involving multiple laboratories.

Main Methods:

• Sample extraction using acetonitrile.
• Isocratic C18 reversed-phase liquid chromatography.
• Mobile phase: ammonium acetate buffer-acetonitrile.
• Detection: fluorescence detection.

Main Results:

• The developed LC method demonstrated effective determination of ethoxyquin in diverse feed samples, including meat meals and extruded pet foods.
• Collaborative study results showed acceptable repeatability and reproducibility across eleven participating laboratories.
• Quantified ethoxyquin levels ranged from 0.25 to 289 ppm, with relative standard deviations for reproducibility up to 55%.

Conclusions:

• The validated LC method provides a robust and accurate means for ethoxyquin determination in animal feeds.
• The method's adoption by AOAC INTERNATIONAL signifies its reliability for routine analysis and quality control in the feed industry.