Magnetic solid-phase extraction of polycyclic aromatic hydrocarbons in water samples by Fe3 O4 @polypyrrole/carbon nanotubes

A magnetic solid-phase extraction method coupled with gas chromatography was proposed for the determination of polycyclic aromatic hydrocarbons in the environmental water samples. The magnetic adsorbent was prepared by incorporating Fe3 O4 nanoparticles, multi-walled carbon nanotubes, and polypyrrole. The main factors affecting the extraction efficiency including the amount of the sorbents, desorption conditions, extraction time, salt concentration, and sample solution pH were investigated and optimized. Under the optimum conditions, good linearity was obtained within the range of 0.03-100 ng/mL for all analytes, with correlation coefficients ranging from 0.9942 to 0.9973. The method detection limits (S/N = 3) were in the range of 0.01-0.04 ng/mL and the limits of quantification (S/N = 10) were 0.03-0.1 ng/mL. Repeatability of the method was assessed through five consecutive extractions of independently prepared solutions at concentrations of 0.1, 10, and 100 ng/mL of the compounds. The observed repeatability ranged 3.4-10.9% depending of the compound considered. The proposed method was successfully applied in the analysis of PAHs in environmental samples (tap, well, river, and wastewater). The recoveries of the method ranged between 93.4 and 99.0%. The procedure proved to be efficient and environmentally friendly.