Trace neonicotinoids analysis in atmospheric particulates by dispersive liquid-liquid microextraction combined with microemulsion electrokinetic chromatography

The analysis of trace pesticides in atmospheric particulate matter (APM) is of great significance for environmental pollution monitoring and human health risk assessment. However, the pesticides that possibly present in APM with complex matrix are at extremely low concentration levels (about pg-ng/m 3 ), which poses a great challenge to analytical methods. In this work, disperse liquid–liquid microextraction (DLLME) was combined with microemulsion electrokinetic chromatography (MEEKC) to improve the enrichment factor (EF) of the method. Sweeping was used for the on-column enrichment, and a new method of DLLME-sweeping-MEEKC was established for the analysis of five neonicotinoids (clothianidin, imidacloprid, thiamethoxam, acetamiprid and thiacloprid). Under the optimal conditions, the extraction recoveries of five neonicotinoids by the DLLME system were 46–81 %. The detection limits of the proposed method for five neonicotinoids were 1.11–4.31 μg/L (in the extract) and 0.93–3.59 ng/m 3 (in the atmosphere, converted by using sampling flow rate of 100 L/min and sampling time of 24 h), and the EF was 1.39 × 10 3 -4.61 × 10 3 times. In real sample analysis, the recoveries of five neonicotinoids in PM 2.5 , PM 10 and TSP were 81.7–110 %, 82.1–114 % and 86.8–113 %, respectively.