Determination of Sudan Dyes Contents in Foods by Three Special Solid Phase Extraction Cartridges Coupled with High Performance Liquid Chromatography

A method was established for the determination of Sudan dyes in foods by special solid phase extraction cartridges combined with high performance liquid chromatography. Samples were extracted with n-hexane,purified and enriched by the solid phase extraction cartridges for Sudan dyes. Afterwards,the elution was dried by the rotary evaporation in a water bath at 40℃ and dissolved with methyl tertiary butyl ether-methanol(4:6 of volume ratio)to a constant volume. Sample solution was separated by Waters Symmetry C₁₈ column(150 mm×4.6 mm,5 μm)with the gradient elution using the mobile phase of acetonitrile-water. Sudan dyes were detected with diode array detection and qualified by the external standard method. Results showed that the linear correlation coefficients of the four Sudan dyes were all above 0.9999 within 0.16~2.56 μg/mL. Detection limits for different kinds of foods were 2.3~9.7 mg/kg. Various brands of SPE cartridges for Sudan dyes had diverse abilities to remove matrix interferences and enrich target analytes,and the suitable SPE cartridge could be selected according to food types. ProElut SDH SPE column was generally suitable for the pretreatment of different kinds of foods. CNW Poly-sery MIP-SDR SPE column was available to the pretreatment of most foods except chili powder. Cleanert Sudan SPE column was applicable for the pretreatment of light-colored and low-fat foods. After treated by ProElut SDH SPE cartridges,recoveries of 6 kinds of foods at the spiked level of 2.0 mg/kg were 83.7%~91.1%,and the relative standard deviations were 2.4%~6.2%(n=6). The method is good at purification and enrichment. Compared with GB/T 19681-2005,it has advantages such as easy operation,good repeatability,high accuracy,short analysis time,solvent saving.