Simple and effective dispersive micro-solid phase extraction procedure for simultaneous determination of polycyclic aromatic compounds in fresh and marine waters

Abstract

In this work, we developed a simple, comprehensive, and effective device and procedure for sample preparation based on dispersive micro-solid phase extraction (d-μ-SPE) for the simultaneous determination of 30 polycyclic aromatic compounds or PACs (including 16 polycyclic aromatic hydrocarbons (PAHs), 3 quinones, and 11 nitro-PAHs) in water samples. The extraction/preconcentration step was carried out in a customized glass device (20–250 mL) using C18 as the sorbent. A mini-UniPrep syringeless filter was used as a desorption device, which allowed one-step desorption, filtration, and injection. The main factors affecting the d-μ-SPE were optimized using the Doehlert design. The optimal d-μ-SPE conditions were 100 mg of C18, 32 min of extraction at 1000 rpm, and 20 min of sonication (at the desorption step). The limit of detection (LOD) for PAHs and nitro-PAHs ranged from 0.8 ng L−1 (phenanthrene) to 1.5 ng L−1 (indene [1,2,3-cd]pyrene) and from 300 ng L−1 (2-nitrofluorene) to 500 ng L−1 (2-nitrobiphenyl), respectively. For quinones, it varied from 1.12 μg L−1 (1,4-naphthoquinone) to 1.70 μg L−1(9,10-phenanthrenequinone). Relative recoveries ranged from 59.1% (benzo[a]pyrene) to 110% (chrysene) for most PAHs and 68.9% (2-nitrofluorene) to 124% (1-methyl-6-nitronaphthalene) for the nitro-PAHs. The recoveries for quinones ranged from 65.3% (9,10-phenanthrenequinone) to 95.3% (9,10-anthraquinone). The enrichment factor varied from 213 (Nap) to 497 (Flu), from 39 (1,4-naphthoquinone) to 254 (9,10-anthraquinone), and from 122 (2-nitrobiphenyl) to 295 (1-methyl-4-nitronaphthalene) for the PAHs, nitro-PAHs, and quinones, respectively. After validation, the procedure was successfully applied toward the determination of PACs in river and marine water samples. Low-molecular-weight PAHs were detected with high frequencies (62.5–100%) and the total PAH concentration ranged from 2.30 ng L−1 (benzo[a]pyrene) to 1070 ng L−1 (pyrene). Quinones were found at concentrations ranging from below the LOD to up to 19.8 μg L−1. The proposed procedure was thus found to be comprehensive, precise, accurate, and suitable for determination of PACs in water samples.