Experimental Design-Based Dispersive Liquid–Liquid Microextraction with GC-FID for Determination of Polycyclic Aromatic Hydrocarbons in Surface Water

Polycyclic aromatic hydrocarbons (PAHs), designated as persistent organic pollutants, are ubiquitous environmental contaminants extensively distributed across surface water ecosystems. This study applies multivariate optimization strategies to a dispersive liquid–liquid microextraction (DLLME) approach for the extraction of acenaphthene, fluorene, anthracene, phenanthrene, fluoranthene, pyrene, benzo(a)anthracene, and benzo(a)pyrene, followed by gas chromatography-flame ionization detection (GC-FID). Extraction selectivity and efficiency were systematically evaluated using extraction and dispersive solvents spanning a range of dielectric constants. A fractional factorial design (FrFD) was used to screen key DLLME variables, followed by Box-Behnken design (BBD) optimization. Separation of all target PAHs was achieved on a DB-5HT column with an analysis time of <19 min. The optimized method was linear over 5–200 μg/L, with limits of detection of 0.11–0.33 μg/L. Good precision was obtained with relative standard deviations of <10% for peak areas and <0.2% for retention times. The method achieved an AGREE greenness score of 0.57, enrichment factors of 19.6–48.1, and recoveries of 65–111%. The validated DLLME-GC-FID method was successfully applied to quantify PAHs in terrestrial waters (wastewater, lake, river, and drain water).