New di-(2-Ethylhexyl)Phosphoric Acid-Based Supramolecular Solvent (DEHPA-SUPRAS) Microextraction Coupled to High Performance Liquid Chromatography (HPLC) for the Determination of Organophosphorus Pesticides in Tea Drinks

Abstract

A new supramolecular solvent (SUPRAS) made up of di-(2-ethylhexyl)phosphoric acid (DEHPA) surfactant its introduced and its application was assessed through the microextraction of organophosphorus pesticides (OPPs) including fenitrothion, phosalone, and chlorpyrifos from tea drinks before being determined by high performance liquid chromatography with ultraviolet detection (HPLC-UV). The method was based upon the extraction of the analytes into the SUPRAS phase spontaneously formed in the ternary mixture of DEHPA, tetrahydrofuran (THF), and the aqueous sample. A phase diagram delimiting the SUPRAS region was constructed and the microstructure of supramolecular aggregates constituting SUPRAS was examined under the optical microscope. After optimizing the main variables in the procedure, the method provided extraction recoveries and preconcentration factors from 77 to 98% and 15 to 19, respectively. The limits of detection (LODs) for the studied pesticides were from 6 to 10 µg L−1. The intra- and inter-day relative standard deviation (RSD) values were from 4.4 to 8.9 and 9.0 to 9.5%, respectively. The developed method has been successfully applied to the several tea drinks and acceptable recoveries for spiked samples were obtained between 82 and 106% with relative standard deviations of less than 9.3%.