Rapid Determination of Illegal Addition of Industrial Dyes in Foods by QuEChERS Using EMR-Lipid Sorbent Combined with Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

An analytical method based on quick, easy, cheap, effective, rugged and safe (QuEChERS) cleanup using an enhanced matrix removal lipid (EMR-Lipid) sorbent combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established for the rapid determination of 57 industrial dyes illegally added in foods. The sample was extracted with acetonitrile, and the extract was purified by QuEChERS. The analytes were separated on an Agilent ZORBAX Eclipse RRHD C₁₈ column (3.0 mm × 150 mm, 1.8 μm) with gradient elution using a mobile phase composed of acetonitrile and 0.1% formic acid, detected using an electrospray ionization source operated under the positive mode with multiple reaction monitoring (MRM), and quantified by an external standard method. The results showed that good linearity was observed for all analytes in the concentration range from 20 to 300 ng/mL with correlation coefficients higher than 0.999. The limits of detection (LOD) and quantitation (LOQ) were 10 and 25 μg/kg, respectively. The recoveries at 3 spiked levels (25, 100 and 250 μg/kg) were 72.1%–119.1%, with relative standard deviations (RSDs, n = 6) of 0.19%–4.58%. The developed method was used to detect illegal addition of industrial dyes in soybean products, condiments, aquatic products, and meat products (n = 20 for each type). Alkaline yellow was detected in one bath of Sichuan pepper powder at a level of 32.9 μg/kg. In conclusion, this method is rapid, accurate, sensitive, and suitable for the determination of the 57 industrial dyes illegally added in foods.