Abstract:

A method was developed for the determination of congo red in beef. The analyte was identified by high performance liquid chromatography-tandem quadrupole time of flight mass spectrometry (LC-QTOF MS) and quantitatively determined by ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry. After purified by liquid-liquid extraction, the congo red in the beef sample was separated on an Agilent ZORBAX Eclipse Plus C₁₈ Rapid Resolution HD UPLC column (50 mm×2.1 mm, 1.8 μm) HPLC, using 95% (volume percentage) methanol as the mobile phase at 0.2 mL/min. The detection was performed on an AB 4000⁺ triple quadrupole mass spectrometer utilizing electrospray ionization (ESI) interface operated in negative ion mode and multiple-reaction monitoring (MRM) mode. The results showed that the linear range of congo red mass concentration was 0.03-1 mg/L with the correlation coefficient of 0.9998. The method had a good precision with the RSDs lower than 5% and the recoveries ranging from 88% to 91%. The limit of detection (LOD) of congo red was 0.01 mg/L. With good reproducibility, the method is simple, fast and effective for the determination of the illegally added congo red in beef and other meat products.

Key words: beef, congo red, high performance liquid chromatography-tandem quadrupole time of flight mass spectrometry (LC-QTOF MS), ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry (UPLC-MS/MS)