Determination of Endocrine Disruptors in Bottom Sediments by Gas Chromatography–Mass Spectrometry with Analyte Preconcentration by Liquid–Liquid and Magnetic Dispersive Solid-Phase Extraction

A method is proposed for the extraction and preconcentration of six of the most common endocrine disruptors (dimethyl, diethyl, dibutyl phthalates; bisphenol A; and octyl- and nonylphenols) from river bottom sediments. The analytes are extracted by two-stage preconcentration. At the first stage, the analytes are extracted from an aqueous solution with an ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate in the presence of a surfactant (sodium dodecyl sulfate). The volumes of the extractant and surfactant solution (12 vol %) are 200 μL and 0.5 mL, respectively. Extraction duration is 2 min. At the second stage, magnetic dispersive solid-phase extraction with magnetic coals of plant origin modified with reversed phases of n-octyltrimethoxysilane and n-octadecyltrimethoxysilane is used. The recovery of analytes by liquid–liquid extraction is 91–99% and by magnetic solid-phase dispersive extraction, 89–99%. It is found that, during solid-phase dispersive extraction, the best conditions for the extraction of disruptors are achieved at pH 5.2–7.0, sorption duration of 5 min using a centrifuge (4000 rpm), and sorbent portion of 25 mg. The use of two-stage preconcentration in combination with gas chromatography–mass spectrometry ensures the determination of endocrine disruptors in bottom sediments at a level of 0.4–0.7 μg/kg.