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

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.The authors would like to thank the Regional Government of Valencia (Spain) (PROMETEO/2018/087) for the financial support, Agilent Technologies Inc. for the loan of the ICP-OES spectrometer, and Ingeniatrics for the OneNeb® provided. Financial support from Universidad Nacional del Sur is gratefully acknowledged. A. S. Lorenzetti, E. Vidal and C. E. Domini wish to thank Consejo Nacional de Investigaciones Científicas y Técnicas for the financial support received. The authors extend their appreciation to the Ministry of Science, Innovation and Universities for granting the Spanish Network of Excellence in Sample Preparation (RED2018-102522-T). This article is based upon work from the Sample Preparation Study Group and Network, supported by the Division of Analytical Chemistry of the European Chemical Society