Switchable solvent-based liquid phase microextraction of copper(II): optimization and application to environmental samples

A switchable solvent-based liquid phase microextraction (SS-LPME) procedure has been established for the preconcentration of copper prior to its determination by microsampling flame atomic absorption spectrometry (FAAS). Triethylamine (TEA) was adopted for the study as a green and cheap switchable solvent. The Cu(II)-1-(2-pyridylazo)-2-naphthol (PAN) complex was extracted into the TEA phase by converting the protonated carbonate (P-TEA-C) to TEA. The experimental conditions have been comprehensively studied and optimized. The limit of detection (LOD) and repeatability (RSD%) of the method were 1.80 mu g L-1 and 3.8%, respectively, and its accuracy was assessed against certified reference materials (TMDA-64.2 fortified water, TMDA-53.3 fortified water, TMDA-51.3 fortified water, 1573a tomato leaves, INCT-OBTL-5 oriental basma tobacco leaves and NCS ZC 8100 2b human hair), and by addition-recovery tests. The SS-LPME-FAAS method was also applied for the determination of trace amounts of copper in water, food and hair samples.