Deep eutectic solvent coated paper: Sustainable sorptive phase for sample preparation

Abstract

Paper-based sorptive phases have gained attention recently due to the low-cost and sustainable character of the cellulosic substrate. However, the sustainability of the resulting phase can be limited by type of coating used for analytes isolation. In this article, this limitation is overcome by using deep eutectic solvents (DES) as coating. To this aim, a Thymol-Vanillin DES is synthesized and deposited on pre-cut cellulose paper strips. The paper-supported DES is employed as sorptive phase for the isolation of selected triazine herbicides for environmental waters analysis. The isolated analytes are finally determined by gas chromatography-mass spectrometry using selected ion monitoring. The method is optimized according to the critical variables that potentially affect its analytical performance such as sample volume, extractant amount, extraction time and sample ionic strength. The method was characterized in terms of sensitivity, accuracy and precision and its applicability was evaluated for the analysis of real environmental water samples. Good linearity values (R2>0.995) were obtained for all the analytes. Limits of detection (LODs) ranged from 0.4 to 0.6 µg L−1 and the precision, expressed as relative standard deviation (RSD) was better than 14.7%. The relative recoveries, calculated in spiked well and river samples, were in the range 90–106%.