Dispersive solid phase micro-extraction of mercury(II) from environmental water and vegetable samples with ionic liquid modified graphene oxide nanoparticles

Abstract

A new dispersive solid phase micro-extraction (dispersive-SPME) method for separation and preconcentration of mercury(II) using ionic liquid modified magnetic reduced graphene oxide (IL-MrGO) nanoparticles, prior to the measurement by cold vapour atomic absorption spectrometry (CV-AAS) has been developed. The IL-MrGO composite was characterized by Brunauer–Emmett–Teller method (BET) for adsorption-desorption measurement, thermogravimetric analysis (TGA), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The method is based on the sorption of mercury(II) on IL-MrGO nanoparticles due to electrostatic interaction and complex formation of ionic liquid part of IL-MrGO with mercury(II). The effect of experimental parameters for preconcentration of mercury(II), such as solution type, concentration and volume of the eluent, pH, time of the sorption and desorption, amount of the sorbent and coexisting ion concentration have been optimized. Under the optimized conditions, a linear response was obtained in the concentration range of 0.08–10 ng mL^-1 with a determination coefficient of 0.9995. The limit of detection (LOD) of the method at a signal to noise ratio of 3 was 0.01 ng mL^-1. Intra-day and inter-day precisions were obtained equal to 3.4 % and 4.5 %, respectively. The dispersive solid phase micro-extraction of mercury(II) on IL-MrGO nanoparticles coupled with cold vapour atomic absorption spectrometry was successfully used for extraction and determination of mercury(II) in water and vegetable samples