Rapid determination of residual synthetic antioxidants in dry animal feed using HPLC-DAD

To ensure the quality and extend the shelf life of dry pet food, the industry uses synthetic antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tertiary-butylhydroquinone (TBHQ), and ethoxyquin, whose use is limited by regulatory agencies to protect animal health. This research aims to propose a new method for determining synthetic antioxidants in dry pet food. The method enables simultaneous analysis of the four most common antioxidants found in cat food and is faster and easier to apply compared to current methodologies. It involves sample preparation through grinding, vortex agitation for extraction with acetonitrile, filtration, and analysis using High-Performance Liquid Chromatography coupled with a Diode Array Detector (HPLC-DAD). The proposed method allowed the identification and quantification of the synthetic antioxidants TBHQ, BHA, ethoxyquin, and BHT in ten samples of dry cat food for adult cats, revealing maximum concentrations of up to 143.9 mg.kg -1 for BHT, with low detection limits and an average R² of 0.992.