The application of new method based on EM-DLLME for analysis of five poly aromatic hydrocarbons by gas chromatography–mass spectrometry

Electro membrane extraction (EME) is a method based on analyte migration from an aqueous sample into an acceptor solution under an applied electrical potential[1]. Inthis work, A highly efficient and simple two-step method, electro membrane extraction followed by dispersive liquid-liquid microextraction (EM-DLLME) and analysis by gas chromatography–mass spectrometry (GC–MS), was developed for the determination of trace level of five poly aromatic hydrocarbons in environmental water samples. This method was applied for determination of tricyclic antidepressants, previously[2]. At this work, for electroactivating of analytes was used initial derivatization the same of that was used in voltammetric technique [3]. In the first step, the analytes were extracted, under electrical potential, from the sample solution into the acceptor solution (acidic aqueous solution), which was held in a polypropylene membrane tube with toluene as the supported liquid membrane. The acceptor solution from the first step was then employed as the sample solution for the second step of (EM-DLLME). In this step, the target analytes were extracted into a solvent with lower density than water (1-octanol) that was dispersed in the sample solution with the assistance of vortex. The extract was separated from the sample solution by centrifugation and collected as the upper layer. Finally, the extract was injected into a GC–MS system for analysis. Five poly aromatic hydrocarbons, naphthalene, acenaphtylene, acenapthene, fluorene and phenanthrene were selected here as model compounds for developing and evaluating the method. The amount of extraction increases when the potential is applied, compared to when the potential is not applied. At the beginning of the research, the response was different in two modes, without potential and with potential. This is relevant to the applied potential area and in a particular potential region, the poly aromatic compounds are partially charged and ionized. Several factors influencing the extraction were investigated using Taguchi design. With the EM-DLLME procedure, high enrichment factors of up to 2710 were achieved. Under the most favorable conditions, good limits of detection (lower than 0.03 μg/L), linearity (R2  0.988) (from 0.07–15 to 0.1– 20 μg/L, depending on the analytes), and repeatability of extraction (RSDs below7.5%, n=5) were obtained. The proposed method was applied to determine poly aromatic hydrocarbons in rain-water samples and good relative recoveries (89-106%)obtained under the optimized conditions.