Optimization of deep eutectic solvent based liquid phase microextraction of PAHs in environmental samples using response surface methodology

The presence of polycyclic aromatic hydrocarbons (PAHs) in wastewater poses significant health risks. To address this, a novel deep eutectic solvent- based ferrofluid (DES-ferrofluid) was developed for liquid phase microextraction with back extraction (LPME-BE) to detect PAHs. The DES-ferrofluid was characterised for its physicochemical properties and morphology using FTIR, VSM and SEM-EDX. Key parameters in the LPME-BE process were optimised using response surface methodology (RSM) based on a Box?Behnken design (BBD). Optimal conditions included 15 mg of tetraethyl orthosilicate- -coated magnetic nanoparticles (MNPTEOS), 25 ?L of DES 1 (caprylic acid and lauric acid), 800 mg NaCl and a 10 min extraction time. Analysis of variance (ANOVA) confirmed strong alignment between experimental data and the model, with an R2 of 0.8799 and adj. R2 of 0.7395. The method achieved limits of detection (LODs) of 0.4?1.7 ng mL-1 and limits of quantification (LOQs) of 1.33?5.67 ng mL-1. Recoveries for spiked samples ranged from 75.78 to 118.65 %, with RSD < 15 %. This DES-ferrofluid LPME-BE method with BBD optimization shows promise as an effective alternative for PAH detection in wastewater samples.