LC-MS/MS Determination of 8 Sudan Dyes in Concentrated Carrot Juice

LC-MS/MS was applied to the determination of 8 Sudan dyes,i.e.,Sudan orange G,Sudan red G,Sudan red 7B,Sudan yellow,Sudan red Ⅰ,Sudan red Ⅱ,Sudan red Ⅲ and Sudan red Ⅳ,in concentrated carrot juice.The sample was extracted by n-hexane,concentrated to near dryness in a rotary evaporator at 39 ℃,and evaporated to dryness by N2-blowing.The residue was dissolved with 1 mL of a mixed solvent of methanol and 0.1%(φ) formic acid(1+1).Hypersil GOLD(50 mm×2.1 mm,1.9 μm) column was used as chromatographic column,and mixtures of methanol and 0.1%(φ) formic acid in various ratios were used as mobile phase in the gradient elution;positive electrospray ionization as well as multiple reaction monitoring mode was used in the detection.Linear relationships between values of peak area and mass concentration of 8 Sudan dyes were kept in the same range of 30-100 μg·L-1,with lower limits of determination(10S/N) in the range of 5-30 μg·kg-1.Tests for recovery were made by addition of standard solutions at 3 different concentration levels,values of recovery found were in the range of 72.0%-96.0%,with values of RSD′s(n=6) in the range of 6.2%-9.6%.