Reversed-phase dispersive liquid-liquid microextraction for elemental analysis of gasoline by inductively coupled plasma optical emission spectrometry

Abstract

In this work a green and fast sample preparation method based on reversed-phase dispersive liquid-liquid microextraction (RP-DLLME) was developed for the separation and preconcentration of several elements (i.e., Ag, As, Ba, Cd, Cr, Cu, Hg, Mn, Mo, Ni, Pb, S, Se, Sn and V) in gasoline samples before determination by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The extraction procedure was carried out in a reverse mode, since a small volume of the aqueous phase (i.e., 8 M HCl) is used to extract a relatively high volume of the organic phase (i.e., gasoline sample). Unlike conventional DLLME, in RP-DLLME the analytes were extracted from the organic phase into the aqueous phase. The experimental conditions for the microextraction procedure were: 5 g of sample, 8 M HCl as the extractant phase, mechanical agitation by vortex as the dispersion system, 115 μL of extractant volume, and 2 min extraction and 5 min centrifugation time. Under optimized extraction conditions the enrichment factor ranged between 3 and 53, and the limits of detection ranged between 0.02 and 50 μg kg-1. The proposed analytical method was validated and successfully used to analyze three gasoline samples. All gasoline samples were spiked at 100 μg kg-1 for all analytes, except sulfur (in this case at 1000 μg kg-1), obtaining recovery and RSD values within the range of 88-109% and 2-9%, respectively.