Researchers from the University of Las Palmas de Gran Canaria in Spain developed new methods for detecting pesticide residues in commercial dry pet food, based off a Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) approach. Their findings were published in the Journal of Chromatography A (1).
cropped view of happy man adding pet food in bowl near akita inu dog. | Image Credit: © LIGHTFIELD STUDIOS - stock.adobe.com
Over 350 million pets reside in Europe, approximately 65% of which are dogs and cats. This has brought with it a focus on pet care and nutrition. A large part of animal health is pet feed, with dry feed being one of the most popular choices due to its extended shelf life and ease of storage, among other benefits. Pet feed can include various components, such as protein sources, fruits, vegetables, and grains. Due to the diverse nature of its composition, pet food comes with an increased risks of introducing harmful compounds, such as mycotoxins and pesticide residues.
Pesticide residues have been detected in the serum, hair, and urine of cats and dogs, highlighting potential exposure through environmental and dietary sources. Pesticide exposure has been associated with several health issues in companion animals, including bladder cancer and mammary tumors in dogs and hyperthyroidism in cats, among others. Despite this, no specific regulations exist for pesticide residues in pet feed in the European Union. In lieu of this, the European Union's Regulation (EC) No 396/2005, which sets maximum residue levels (MRLs) for feed of plant and animal origin for production animals, is typically referenced.
In this study, the researchers validated a Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS)-based multi-residue method for analyzing 211 pesticide residues in cat and dog feed through liquid chromatography–tandem mass spectrometry (LC–MS/MS) and gas chromatography–tandem mass spectrometry (GC–MS/MS). They particularly focused on optimizing clean-up to address challenges posed by high-fat matrices. Three different clean-up strategies were tested: d-SPE with PSA, Enhanced Matrix Removal-Lipid (EMR-Lipid), and freezing-out, both alone and in combination with each other. The validated method was then further tested on commercial samples to evaluate their applicability.
The freeze-out yielded the best results, with 91.9% of analytes achieving recoveries within 70–120% and RSDs ≤ 20%, and using two freezing cycles proved sufficient for effective matrix removal while maintaining analyte recoveries. According to the scientists, this is the first validated QuEChERS method to use freezing-out as a standalone clean-up strategy, offering a simplified and cost-effective solution for high-fat matrices. The method was then validated in terms of linearity, accuracy, and precision. Matrix-matched calibration curves (R² ≥ 0.99) were used for all analytes. Recoveries were within 70–120 % for all spiking levels in most compounds, with a few analytes showing recoveries between 60–130 % in the extended range allowed by SANTE guidelines. All RSDs were below 20 % by established validation guidelines.
Overall, the method demonstrated high sensitivity, with most analytes achieving limits of quantification (LOQs) below the generic 10.0 µg/kg MRL established by EU feed regulations. All limits of detection (LODs) were equal to or below 10.0 µg/kg. Further, the method was demonstrated by analyzing 16 commercial pet feed samples, where 112 residues of 39 pesticides were detected.
(1) Macías-Montes, A.; Luzardo, O. P.; Zaccaroni, A.; Acosta-Dacal, A. Optimization and Validation of a QuEChERS-Based Method with a Freezing-Out Clean-Up for Pesticide Residues in Commercial Dry Food for Dogs and Cats. J. Chromatogr. A 2025, 1756, 466093. DOI: 10.1016/j.chroma.2025.466093
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