Simple and effective dispersive micro-solid phase extraction procedure for simultaneous determination of polycyclic...

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.