Simultaneous determination of fat-soluble vitamins and carotenoids in human serum using a nanostructured ionic liquid based microextraction method

•A SAIL-based DLLME was used to extract fat-soluble micronutrients from human serum.•The liquid crystal structured DLLME was found to be simple, fast and efficient.•A HPLC method was established to simultaneously determine 10 micronutrients.•The DLLME and HPLC method was fully validated and had been successfully applied. The determination of fat-soluble vitamins and carotenoids in human serum provides reliable information for diagnosing malnutrition and for establishing appropriate intervention programs. Due to the complex composition of the biological samples, the efficient sample preparation is the key to the analysis. We report here a surface active ionic liquid (SAIL)-based dispersive liquid-liquid microextraction (DLLME) method coupled with a high performance liquid chromatography (HPLC) to determine four fat-soluble vitamins and six carotenoids in human serum simultaneously. Liquid crystal structures were formed in the extract phase. And the enrichment factor of the analytes treated by DLLME was 4 to 26 times of the traditional LLE method except lycopene. The limit of determination for these compounds was determined to be between 0.002 and 0.076 µg/mL. The accuracy was validated by the standard addition method with recoveries ranging from 82.4 to 114.1%. The intra-day and inter-day relative standard deviations were 2.76–12.63% and 4.01–13.54%, respectively. The proposed DLLME coupled with the HPLC method was successfully applied in the determination of fat-soluble micronutrients in human serum.