Extensible automated dispersive liquid-liquid microextraction

Songqing Li; Lu Hu; Ketao Chen; Haixiang Gao

doi:10.1016/j.aca.2015.02.061

Extensible automated dispersive liquid-liquid microextraction

Anal Chim Acta. 2015 May 4:872:46-54. doi: 10.1016/j.aca.2015.02.061. Epub 2015 Feb 27.

Authors

Songqing Li¹, Lu Hu¹, Ketao Chen¹, Haixiang Gao²

Affiliations

¹ Department of Applied Chemistry, China Agricultural University, Yuanmingyuan West Road 2#, Haidian District, Beijing 100193, China.
² Department of Applied Chemistry, China Agricultural University, Yuanmingyuan West Road 2#, Haidian District, Beijing 100193, China. Electronic address: hxgao@cau.edu.cn.

PMID: 25892068
DOI: 10.1016/j.aca.2015.02.061

Abstract

In this study, a convenient and extensible automated ionic liquid-based in situ dispersive liquid-liquid microextraction (automated IL-based in situ DLLME) was developed. 1-Octyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide ([C8MIM]NTf2) is formed through the reaction between [C8MIM]Cl and lithium bis[(trifluoromethane)sulfonyl]imide (LiNTf2) to extract the analytes. Using a fully automatic SPE workstation, special SPE columns packed with nonwoven polypropylene (NWPP) fiber, and a modified operation program, the procedures of the IL-based in situ DLLME, including the collection of a water sample, injection of an ion exchange solvent, phase separation of the emulsified solution, elution of the retained extraction phase, and collection of the eluent into vials, can be performed automatically. The developed approach, coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD), was successfully applied to the detection and concentration determination of benzoylurea (BU) insecticides in water samples. Parameters affecting the extraction performance were investigated and optimized. Under the optimized conditions, the proposed method achieved extraction recoveries of 80% to 89% for water samples. The limits of detection (LODs) of the method were in the range of 0.16-0.45 ng mL(-1). The intra-column and inter-column relative standard deviations (RSDs) were <8.6%. Good linearity (r>0.9986) was obtained over the calibration range from 2 to 500 ng mL(-1). The proposed method opens a new avenue for automated DLLME that not only greatly expands the range of viable extractants, especially functional ILs but also enhances its application for various detection methods. Furthermore, multiple samples can be processed simultaneously, which accelerates the sample preparation and allows the examination of a large number of samples.

Keywords: Automated dispersive liquid–liquid microextraction; Benzoylurea insecticides; Fully automatic SPE workstation; Ionic liquid; Nonwoven polypropylene fiber.