Room-temperature synthesis of ionic liquid@covalent organic frameworks for the solid phase extraction and analysis of six herbicides from water samples

Abstract

Waters contaminated with pesticides poses a potential hazard to ecosystems and human health, so sensitive and efficient analytical methods are essential for water monitoring. Herein, in order to efficiently extract six commonly used herbicides, a novel ionic liquid covalent organic framework (IL@COF) was prepared using a simple room-temperature synthesis in this study. As an adsorbent for solid phase extraction (SPE), the mesoporous material exhibits rapid adsorption performance for six typical herbicides from water samples. Under the optimal experimental conditions, wide linearities (500 ∼ 20,000 μg L–1) and low limits of detection (prometryn: 17.9 μg L–1; metribuzin: 36.7 μg L–1; bentazon: 14.5 μg L–1; isoproturon: 18.0 μg L–1; acetochlor: 19.6 μg L–1; butachlor: 37.1 μg L–1) for six analytes were obtained via high performance liquid chromatography (HPLC). The adsorbent has stable physical and chemical properties and can be reused for 10 times after effective elution. The applicability of this method is further evaluated by analyzing ten kinds of real water sample. The recoveries of six kinds of herbicides ranged from 85.3 % to 122.9 %. The mechanism of adsorption is the interaction between hydrogen bond acceptor and donor. These results indicate that HPLC after SPE with a new type of IL@COF as the SPE adsorbent is a promising technique for the simultaneous detection of six pesticides in environmental water samples.