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Nonionic surfactants based hydrophobic deep eutectic solvents for liquid-liquid microextraction of Sudan dyes in
Jia Chen1, Xiao Li2, Anqi Huang2
1Key Laboratory of Combinatorial Biosynthesis and Drug Discovery (Ministry of Education), and School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China; Scientific Research Center, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China.
Abstract:
A new type of high-density hydrophobic deep eutectic solvents (DESs) were synthesized with nonionic surfactants as hydrogen bond acceptors and hexafluoroisopropanol (HFIP) as hydrogen bond donor. Brij-35 was selected as the optimal nonionic surfactant for the preparation of Brij-35-HFIP-DES (molar ratio 1:20). A vortex-assisted DES-based liquid-liquid microextraction method was proposed for determination of Sudan dyes in tomato chili sauces. The whole pretreatment process only needs 5 min and 1.1 mL of organic solvent. The method with HPLC-DAD shows high efficiency (enrichment factors 89-176 and extraction rates 61.0-74.6%) and good performance with linearity (R ≥ 0.9997) in 0.04-2 μg g-1 range, detection limits of 0.0045-0.0118 μg g-1, recoveries of 91.6-104.5% and intra-/inter-day precision below 8.0%. A "DES in water in DES" aggregate microstructure was observed in DES-rich phase. The proposed method is simple, quick, eco-friendly, and suits for the efficient extraction and accurate determination of Sudan dyes in tomato chili sauces.

