In-situ ionic liquid-dispersive liquid-liquid microextraction (IL-DLLME) method was developed as a pretreatment method for the detection of six chlorophenols (CPs) in honey samples. The hydrophobic ionic liquid [C4MIM][NTf2], formed in-situ by the hydrophilic ionic liquid [C4MIM][BF4] and the ion exchange reagent LiNTf2 was used as the microextractant solvent of CPs from honey sample. Then the enriched analytes were back-extracted into 40 μL of 0.14 M NaOH solution and finally subjected to analysis by high-performance liquid chromatography. The method showed low limit of detection of CPs, 0.8-3.2 μg/L and high enrichment factor, 34-65 with the recoveries range from 91.60% to 114.33%. The method is simple, rapid, environmentally friendly and with high extraction efficiency.

The aim of this work is to shed light on the origins of unique properties by studying the relationship between viscosity and hydrogen‐bonding interactions of terpene‐based natural deep eutectic solvents (NADES). Five systems including camphor/formic acid, menthol/acetic acid, menthol/β‐citronellol, menthol/lactic acid, and thymol/β‐citronellol are prepared (molar ratio 1:1). Their structures and nature of the associated hydrogen bonds are investigated through multiple methods and theories. The viscosity of NADES is consistent with the product of hydrogen‐bond number and lifetime. Through visualization of non‐covalent interactions, terpene‐acid‐based NADES with single sites show the lowest viscosity among the studied systems because of weak and unstable hydrogen bonding. Inversely, multi‐site terpene‐acid‐based NADES possess relatively high viscosity. Owing to the stability of hydrogen bonds in the network, the terpene‐terpene‐based system is in the middle level of viscosity. In‐depth analysis of these hydrogen bonds shows that they can be classified as “weak to medium” and are mainly derived from electrostatic interactions. Moreover, there is an obvious connection between viscosity and hydrogen‐bonding strength (integrated core‐valence bifurcation index) in the networks. The discovery of intrinsic rules between viscosity and hydrogen‐bonding interactions is beneficial for the design of novel low‐viscosity NADES in the future.