Studies On The Extraction Method Of Sudan Dyes In Environmental And Foodstuff Samples

Sudan dyes are a group of synthetic lipophilic azo dyes and widely used ascoloring agents in industry. Due to the dyes and their metabolites may cause liver,spleen and bladder cancer, International Agency for Research on Cancer (IARC) hascategorized Sudan dyes as class3carcinogen. However, the dyes are lost inevitablyduring dyeing operation and easily enter environmental water system with industrialeffluents. In addition, Sudan dyes were unlawfully added in foodstuffs insteadof the coloring agent in food by unscrupulous merchants to restore the natural colorsduring the processing. Therefore, to protect human health and guarantee food security,it is very necessary to develop an efficient, convenient and green extraction method.Different pretreatment methods were established for extraction of Sudan dyes(Sudan I-IV) in environmental and foodstuff samples. There are two parts in thethesis:1. Homogeneous ionic liquid microextraction of Sudan dyes from environmental andfoodstuff samplesHomogeneous ionic liquid microextraction was introduced for extracting Sudandyes from water and foodstuff samples followed by detection using ultrafast liquidchromatography. The extraction of the analytes and formation of insoluble ionicliquid can be performed simultaneously. The consumption of organic solvent was very low, which could be considered as a green analytical method. Under the optimizedconditions, the limits of detection and quantification of the analytes were in the rangeof0.299-0.655ng/mL and0.989-2.162ng/mL, respectively. The intra-day andinter-day precision were in the range of1.29-4.68%(n=5) and2.11-6.41%(n=5),respectively. Recoveries obtained by analyzing seven kinds of real samples werebetween65.95and112.82%with the relative standard deviations lower than6.41%.The present method is more convenient, faster and environmentally friendlier thanother extraction methods.2. Magnetic solid-phase extraction of Sudan dyes in environmental water samplesMagnetic solid-phase extraction based on Fe3O4@polyaniline particles followedby ultrafast liquid chromatography was applied for determination of Sudan dyes inenvironmental water samples. The magnetic adsorbent can be used repeatedly. Underthe optimized conditions, the limits of detection of four kinds of Sudan dyes were0.041-0.151ng/mL and quantifications were0.989-2.162ng/mL, respectively. Theintra-day and inter-day precision were lower than6.8%. Recoveries obtained byanalyzing five kinds of environmental water samples were in the range of92.4-106.9%. Compared with other extraction methods, the present method is moreeffective with the advantages of convenience, low solvent consumption, shortextraction time and cost saving.