Modified QuEChERS-LC-MS/MS for the simultaneous detection of eight prohibited dyes in complex food matrices: method validation and application to real samples

Abstract

The illicit use of industrial dyes in food products remains a critical food safety concern due to their potential toxicity and carcinogenic properties. This study developed and validated a robust method for the simultaneous determination of eight prohibited organic dyes (Auramine O, Rhodamine B, Chrysoidine G, Methylene Blue, Brilliant Green, Sudan Yellow, Toluidine Red, and Sudan Red G) in various food matrices using a modified QuEChERS extraction technique coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The extraction procedure was optimized to maximize recovery efficiency, effectively remove matrix interferences, and enhance analytical sensitivity. The LC-MS/MS system operated in multiple reaction monitoring (MRM) mode, utilizing a C18 column and a gradient mobile phase to achieve efficient separation of dyes with diverse physicochemical properties. The method demonstrated high linearity (R² > 0.9991), with limits of detection (LOD) ranging from 0.048 to 2.868 µg kg⁻¹ and limits of quantification (LOQ) from 0.160 to 9.561 µg kg⁻¹. Recoveries ranged between 76.8% and 113.1%, with repeatability (RSD_r) < 15% and intermediate precision (RSD_iR) < 22% across complex matrices such as chili sauce, wine, sausage, durian, dried chili, and potato chips. The proposed method is rapid, accurate, and highly selective, making it suitable for current routine food safety monitoring programs.