Experimental and density functional theory studies during a new solid phase extraction of phenolic compounds from wastewater samples prior to GC–MS determination

In this work a commercial polymer-based dispersive solid phase extraction approach has been used in phenolic compounds extraction from wastewater samples. In the extraction procedure, firstly the sorbent (polyvinylpyrrolidone) forms a homogenous solution with aqueous phase contacting the analytes and then its solubility was decreased by adding sodium chloride which leads to its dispersion into the aqueous solution as tiny particles. During this step, the investigated phenolic compounds were adsorbed onto the polymer. Then, a deep eutectic solvent synthesized from choline chloride and alpha-terpineol was used for elution of the compounds from the polymer surface. Optimization of the effective factors showed that the subsequent conditions are suitable for extraction of the analytes: sorbent (polyvinylpyrrolidone) amount, 125 mg; sample solution pH, 4; NaCl concentration, 20%, w/v; and desorption solvent volume, 75 µL. Acceptable figures of merit consist of limits of detection and quantification in the ranges of (0.13–0.36 ng/mL and 0.43–1.2 ng/mL, relative standard deviations ≤ 6%, and extraction recovery and enrichment factor in the ranges of 60–92% and 80–122 were obtained. The powers of the interactions between the studied chemical species were analyzed with the help of Conceptual Density Functional Theory calculations and important quantum chemical parameters related to the chemical reactivity. The obtained theoretical data were in a good agreement with experimental observations.