Utilization of inverted dispersive liquid–liquid microextraction followed by HPLC-UV as a sensitive and efficient method for the extraction and determination of quercetin in honey and biological samples

A sensitive, rapid and efficient method for the extraction of quercetin as well as its determination in honey and biological samples was developed using inverted dispersive liquid–liquid microextraction (IDLLME) and HPLC-UV. The extraction method is based on the application of an extracting solvent lighter than water in the ternary component solvent (aqueous solution: extracting solvent: disperser solvent) system. The extraction parameters such as type and volume of extracting and disperser solvent, pH of sample, stirring rate and extraction time were optimized. Under the optimal conditions (extracting solvent: 100 μL 1-octanol; disperser solvent: 300 μL acetonitrile; pH of sample: 4.5 and stirring rate: 1000 rpm) a linear calibration curve was obtained in the range of 0.5–1000 ng mL−1 with R2 = 0.9993 (n = 10). The limits of detection and quantification were 0.26 and 0.78 ng mL−1, respectively. The extraction recovery was 97% and the preconcentration factor was 243. While the relative standard deviation for 25 ng mL−1 was 3.51 (n = 5), it was 2.12 (n = 5) for 500 ng mL−1 of quercetin. The method was successfully applied for the preconcentration and determination of quercetin in honey, urine and plasma samples.