title: Rapid and sensitive analysis of microcystins using ionic liquid-based in situ dispersive liquid-liquid microextraction.
abstract: Three structurally different ionic liquids (ILs), namely 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]), 1-(6-hydroxyethyl)-3-methylimidazolium chloride ([HeOHMIM][Cl]) and 1-benzyl-3-(2-hydroxyethyl)imidazolium bromide ([BeEOHIM][Br]), were applied as extraction solvents using in situ dispersive liquid-liquid microextraction (in situ DLLME) for the preconcentration of two microcystin variants, microcystin-RR (MC-RR) and microcystin-LR (MC-LR) from aqueous samples. Extraction parameters including sample solution pH, ratio of IL to metathesis reagent, sample volume, IL quantity, and salt concentration were optimized to achieve the best extraction efficiency. The [BeEOHIM][Br] IL, which contains both an aromatic moiety and a hydroxyl group within its chemical structure, exhibited superior extraction efficiency compared to the other two ILs. The analytical performance of the [BeEOHIM][Br] IL as an extraction solvent for in situ DLLME of microcystins was investigated using HPLC-UV and HPLC-MS. The limits of detection (LODs) for MC-RR and MC-LR were 0.7μgL(-1) using UV detection with a linear range from 1 to 50μgL(-1). The separation method was successfully adapted for ESI-MS/SIM detection, wherein the LODs for MC-RR and MC-LR were greatly improved to 0.005 and 0.003μgL(-1), respectively. The accuracy of the method was demonstrated by examining the relative recovery using tap water and river water and produced recoveries ranging from 45.0 to 109.7% and from 46.3 to 103.2%, respectively.
authors.affiliation: Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA.
authors.forename: Honglian
authors.initials: H
authors.lastname: Yu
authors.affiliation: Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA.
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Clark
authors.affiliation: Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA; Department of Chemistry, Iowa State University, Ames, IA 50011, USA. Electronic address: andersoj@iastate.edu.
authors.forename: Jared L
authors.initials: JL
authors.lastname: Anderson
mesh_terms: D002853:Chromatography, Liquid; D052578:Ionic Liquids / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D057230:Limit of Detection; D059627:Liquid Phase Microextraction; D013058:Mass Spectrometry; D052998:Microcystins / Q000032:analysis*; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D052578:Ionic Liquids; D007477:Ions; D052998:Microcystins; D014874:Water Pollutants, Chemical; D014867:Water; C078588:microcystin
keywords: Cyanobacterial blooms; Dispersive liquid–liquid microextraction; High performance liquid chromatography; Ionic liquid; Microcystin