Abstract

This paper illustrates the development of a procedure based on the use of a low transition temperature mixture (LTTM) for the dispersive liquid-liquid microextraction (DLLME) of fungicides, insecticides and acaricides from surface waters. The LTTM preparation involves the heat-mixing of choline chloride and acetylsalicylic acid in a molar ratio 1:2 (ChCl(ASA)(2)). The resulting mixture appears as a clear viscous liquid at room-temperature, denser than water (1.20 +/- 0.01 g mL(-1)). For its characterization, differential scanning calorimetry (DSC) provided crucial evidence to classify it as a LTTM rather than as a deep eutectic solvent (DES) since it revealed an intense glass transition at -37 degrees C. Large-angle X-ray scattering (LAXS) confirmed the lack of any long-distance order. Due to the LTTM immiscibility with water, an evaluation study was carried out to test ChCl(ASA)(2) as an effective alternative to the conventional chlorinated solvents for DLLME. To this end, 24 pesticides were used as model compounds, extracted from surface water samples (5 mL) and analyzed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The definitive procedure required the optimization of some key parameters such as volume of extracting solvent, type and volume of dispersing solvent, volume of the aqueous sample, LTTM dispersion procedure, and extraction time. Depending on pKa and logP values, recoveries ranged from 18 (for very polar compounds) to 96%, revealing that the ideal candidates for the extraction with ChCl(ASA)(2) are neutral compounds with logP >2. After complete validation, the method was applied to analyze water samples from the River Tiber where dodine and dimetomorph were found at low mu g L-1 concentration levels. (C) 2019 Elsevier B.V. All rights reserved.

Keywords

Low transition temperature mixture; Deep eutectic solvents; Dispersive liquid-liquid microextraction; Sample preparation; Environmental samples; LC-MS

Published in

Journal of Chromatography A
2019, Volume: 1605, article number: 360329
Publisher: ELSEVIER

SLU Authors

• Persson, Ingmar

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

Ensure availability and sustainable management of water and sanitation for all
Ensure healthy lives and promote well-being for all at all ages


UKÄ Subject classification

Environmental Sciences
Analytical Chemistry


Publication identifier

DOI: https://doi.org/10.1016/j.chroma.2019.06.050

Permanent link to this page (URI)

https://res.slu.se/id/publ/103176