Determination of Paraquat in Environmental Water by Ionic Liquid-Based Liquid Phase Extraction with Direct Injection for HPLC

A simple method for the determination of paraquat in environment samples was developed. 1‑Ethyl-3-methylimidazolium ethyl sulfate and anhydrous potassium hydrogen phosphate were used to form aqueous two-phase system. The system was applied to the extraction of paraquat and its determination by HPLC. To achieve optimum extraction performance, several experimental parameters, including the type and the amount of salt, the amount of ionic liquid, extraction time, were investigated and optimized. Under the optimal experimental conditions, good linearity was observed in the range of 10–5 × 103 ng/mL. The limit of detection was 8 ng/mL along with enrichment factor of 18. The phase behavior of aqueous two-phase system and extraction mechanism were investigated by UV-Vis spectroscopy. The present method was successfully applied to the determination of paraquat in environment samples, and the recovery was in the range of 92.3–95.1%. The results showed that the present method is rapid, feasible and environmentally friendly.