Statistical optimization of surfactant assisted dispersive liquid-liquid microextraction for trace mercury determination by GF-AAS

Abstract

A new method of surfactant assisted dispersive liquid-liquid microextraction prior to graphite furnace atomic absorption spectroscopy (GF-AAS) has been developed for determination of trace amounts of mercury in aqueous solutions. In this method, Triton X-114 (TX-114), a non-ionic surfactant, compared with DLLME, was substituted as disperser solvent and emulsifier agent that could afford effective emulsification and make the extraction comparatively greener. The effects of different experimental factors on the extraction was examined using two experimental design methods; a screening design to identify more effective parameters and a central composite design at five levels of the operating parameters to find out optimum values. Under the optimal conditions, the limit of detection (LOD) for mercury was 0.023 µg.L−1, with enhancement factor (EF) of 125 and the relative standard deviation (RSD) of 8.1% (n= 5, C = 1.0 µg.L−1). The proposed method was applied for preconcentration and determination of mercury in different aqueous samples and the recoveries for the spiked samples were in the range of 95 – 106%.