Application of Effervescent Tablets Based on Magnetic Charcoal for the Preconcentration and Determination of Dichlorophenoxyacetic Acids and Their Metabolites by Gas Chromatography–Mass Spectrometry in Soils and Natural Waters

Abstract

A method for obtaining effervescent tablets, consisting of magnetic carbon, tartaric acid, sodium carbonate and sodium bicarbonate, and their use for the adsorption of dichlorophenoxycarboxylic acids (DCPA)—2,4-dichlorophenoxyacetic, 2,4-dichlorophenoxypropionic and 2,4-dichlorophenoxybutyric acids and their metabolites—2,4-dichlorophenol and 4-chlorophenol is proposed. The tablets are immersed in an analyzed solution with a neutral reaction medium. To analyze soils, extraction with an alkali solution followed by the neutralization of the extract is carried out. After CO2 separation is completed, the sorbent is removed with a neodymium magnet and the analytes are desorbed with acetone. The acetone extract is evaporated under a stream of nitrogen, and the concentrate is analyzed by gas chromatography–mass spectrometry. The method was tested on model systems—samples of river water and typical chernozem, which were artificially contaminated with DCPA and chlorophenols (CP). In analyzing river waters, the limits of determination for DCPA are 0.7–0.9 μg/L, for CP—40 ng/L. In soils, the limit of detection is 3–4 and 0.1 μg/kg for DCPA and CP, respectively.