Rapid determination of 61 acid dyes in chili paste, hotpot seasoning, and bearnaise using double liquid-liquid extraction and UHPLC-Q-Orbitrap-MS.

Abstract

The aims of this study were to establish a novel method for simultaneously determining 61 acid dyes in chili, hotpot seasoning, and bearnaise sauce using double liquid-liquid extraction (d-LLE) technology. A mixture of water, methanol, and dichloromethane (1:3:1, v/v/v) was used as the extraction solution, which was actively separated into aqueous and organic phases at a fixed ratio. The clean-up step was initially completed by discarding the organic phase layer, which contained abundant lipophilic compounds. Subsequently, the aqueous phase was further separated by salting out, which effectively removed interference from the highly hydrophilic compounds. As a result of these two purification steps, the matrix suppression effect was significantly reduced by a minimum of 16.9%. Finally, the extract was analyzed using an ultrahigh-performance liquid chromatography-quadrupole Orbitrap mass spectrometer (UHPLC-Q-Orbitrap-MS), and the characteristic ion fragments (SO3 - , m/z 79.9557) of the acid dyes were utilized for the preliminary qualitative analysis. The results showed that the 61 acid dyes showed a good linear relationship in the range of 0.01-0.2µg/mL, and the limit of quantification (LOQ) was 0.01mg/kg. The average recoveries were 74.3%-99.7%, with relative standard deviations (RSD) ≤10%. The proposed method can rapidly identify and quantify acid dyes in complex foods at a low cost, with high sensitivity and reliability.