Thin film microextraction of PAHs from wastewater samples using an oxine modified iron mesh followed by dispersive liquid–liquid microextraction prior to gas chromatography analysis

In the present research, an attempt has been made to develop a new thin film microextraction method for the extraction of several polycyclic aromatic hydrocarbons from aqueous samples collected from different industrial units prior to their analysis by gas chromatography combined with a flame ionization detector. In this approach, a thin iron mesh was modified by the formation of iron(II) oxinate on its surface and used for the extraction of analytes without an additional sorbent. For this purpose, first, the mesh was immersed in a sulfuric acid solution and then transferred into an 8-hydroxy quinoline (oxine) solution dissolved in ammonia solution. By doing so, iron(II) oxinate was formed on the surface of the mesh and enhanced its adsorption efficiency towards the analytes. It is worth noting that the unique structure of the prepared mesh provided a large contact area and high affinity for adsorption of the analytes. After desorption of the analytes from the sorbent surface with an elution solvent, the analytes were more concentrated by performing dispersive liquid-liquid microextraction. Under optimum conditions, the method demonstrated limits of detection and quantification within the ranges of 0.27-54 and 0.89-1.7 ng mL^-1, respectively. The relative standard deviation values for intra- and inter-day precisions ranged from 5.2-8.1% and 8.2-11.6%, respectively. Furthermore, the enrichment factors for the target analytes varied between 200 and 255, while the extraction recoveries fell within the range of 40-51%. These findings illustrate the sensitivity, precision, and effectiveness of the method for quantifying the desired analytes.