Determination of Four Sudan Dyes in Chili Products Using Ultra-high Performance Liquid Chromatography-tandem Quadrupole Mass Spectrometry

Using a basic alumina column, which has stronger reaction with sudan dye, as a solid phase extraction(SPE) column, an ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry(UPLC-MS) method was developed for the determination of four sudan dyes in chili products. The extraction solvent, washing liquid for the SPE column, eluent solvent, and liquid chromatography conditions were optimized separately. The sudans were extracted by using 10 m L mixed acetonitrile and dichloromethane solution(3:2, V/V) was used to extract the Ten milliliters of n-hexane and 4 m L mixed ethyl acetate and n-hexane(1:1, V/V) were used as washing liquids. Twelve milliliters of a mixed 5% acidified methanol and ethyl acetate solution(1:1, V/V) was used for elution. An ACQUITY BEH C18 chromatography column(2.1 × 100 mm, 1.7 μm) was used with mobile phases composed of 0.3% formic acid acetonitrile solution and 0.3 % formic acid water solution. The substrate spiked standard curves of the four sudan dyes had good linear correlations in the range 10~500 μg/L, with all correlation coefficients above 0.995. The limits of detection(LOD) of the four sudan dyes were 5.0, 5.0, 4.0, and 4.0 μg/kg. The recovery experiment, performed by adding samples, was carried out with blank samples at concentrations between 10-150 μg/kg. The average recovery ratio was 71.4%~104.2%, and the relative standard deviation(RSD, n = 6) was 4.6%~8.9%. Three hundred and eighty samples were examined using this method, and 36 samples were positive for sudans, and the component was primarily sudan IV.