Development and Validation of Reliable Quantitative Methods for Ethoxyquin in Chicken by Fluorescence Detection (LC-FLD) and Isotope Dilution Tandem Mass Spectrometry (LC-IDMS/MS)

Abigail Grace Bion, Aaron Dacuya, Alleni Junsay, Benilda Ebarvia

Abstract

Ethoxyquin (EQ), a quinoline-based antioxidant, is widely used in food and animal feed, often leading to residues in animal tissues—raising health concerns. This study developed and validated two quantification methods: liquid chromatography with fluorescence detection (LC-FLD) and isotope dilution tandem mass spectrometry (LC-IDMS/MS). Sample preparation employed the QuEChERS technique with enhanced matrix removal-lipid (dSPE EMR-lipid). The LODs/LOQs were 2.4/3.6 μg/kg (LC-FLD) and 1.7/2.5 μg/kg (LC-IDMS/MS). Both methods showed excellent linearity (R = 0.999) using matrix-matched calibration. Recoveries at three spiking levels ranged from 94% to 106%, while repeatability (RSD ≤ 4.2%, n = 10) and intermediate precision over one, two, and three month period (RSD ≤ 7.6%, n = 3) complied with Horwitz criteria. The methods proved suitable for reliable EQ monitoring in chicken and similar matrices and were fit-for-purpose for homogeneity and stability studies and reference value assignment of a chicken-based reference material.

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IMEKO-TC8-11-24-2025-006.pdf

DOI

10.21014/tc24-2025.006

IMEKO TC

TC24 - Chemical Measurements

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