Double salting-out effect assisted heat-shrinkable tubing liquid phase microextraction followed by high performance liquid chromatography for determination of flavonoids in human plasma

This paper proposed a double salting-out effect assisted heat-shrinkable tubing liquid phase microextraction (LPME). In the study, a low price and handy heat-shrinkable tubing was used as carrier of extraction solvent and salt film, which was placed in sample solution containing certain concentration of salt for concentrating and enriching flavonoids from human plasma. Through the double salting-out effect in different regions, this microextraction method has a good present to enhance the extraction efficiency and enrichment factors of the target analytes. Several key parameters affecting the extraction efficiency were investigated, including the type of extraction solvent, the occurring region of salting-out effect, salt concentration, pH of sample phase, stirring rate, extraction time, and volume of sample phase. Also, the mechanism of the procedure was described. Under the optimum conditions, excellent linearities with r >= 0.9912 were obtained, the limits of detection were 2.5-150 ng/mL, the average recoveries ranged from 90.3% to 111.2%. In the new procedure, the low-cost and stable heat-shrinkable tubing was first used as carrier in LPME, combined with high performance liquid chromatography (HPLC), has been successfully applied for the determination of the trace-level target analytes in human plasma. (C) 2019 Elsevier B.V. All rights reserved.