Multi-walled carbon nanotubes for the dispersive solid-phase extraction of the phytoestrogen genistein from water samples using high performance liquid chromatography

A modified method based on dispersive solid-phase extraction (dSPE) combined with high performance liquid chromatography (HPLC) was developed for the determination of genistein (GEN) in water samples. In this study, multi-walled carbon nanotubes (MWCNTs) were used as a dSPE adsorbent for the preconcentration of analytes. HPLC was used for separation and detection. This is the first time that GEN was simultaneously extracted and preconcentrated by MWCNTs-based dSPE. Several experimental parameters, including the amount of sorbent, extraction time, pH and ionic strength of sample solution, and desorption conditions, were evaluated. Besides, the adsorption type, and dynamics and thermodynamics of adsorption of GEN on MWCNTs were investigated in detail. Under optimal experimental conditions, good linearity was observed in the range of 1.0-500.0 ng mL(-1) with a correlation coefficient of 0.9990. The limit of detection and quantification were 0.29 ng mL(-1) and 0.97 ng mL(-1), respectively. The MWCNTs have higher stability within eight removal-regeneration recycles and up to 95% of recovery could be achieved using ionic liquid elution. The present method was applied to the analysis of different water samples, and the recoveries of GEN obtained were in the range of 88.3-101.4% with relative standard deviations lower than 6.8%. The results showed that the proposed method is a rapid, convenient and feasible method for the determination of GEN in water samples.