Ionic liquid-based hollow fiber liquid-phase microextraction for the determination of trace lead (II) in environmental water and tea drinks samples by graphite furnace atomic absorption spectrometry

摘要

A three-phase hollow fiber liquid-phase microextraction (HF-LPME) was used to determine the trace amounts of Lead (II) in environmental water and tea drinks. In this approach, green solvent ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM]PF6) was used as membrane carrier that dissolved in hollow fiber pores. 1-(2-Pyridylazo)-2-naphthol (PAN) was placed in aqueous solution to form hydrophobic complex with Pb(II). Ethylene diamine tetraacetic acid (EDTA) was used as stripping agent that it can form water-soluble complex with Pb(II). After extraction, the acceptor solution was directly injected into the graphite furnace atomic absorption spectrometry (GF-AAS) for analysis. Some important parameters that influence the extraction efficiency were investigated, such as PAN concentration, pH, EDTA concentration, stirring rate, extraction time, and interfering metal ions. Under the optimized conditions, an enrichment factor (EF) of 210 and a limit of detection (LOD) of 0.004 ng mL(-1) were obtained. The calibration curve was linear in the range of 0.05-0.5 ng mL(-1) (R = 0.999). The relative standard deviation (RSD) at the 0.12 ng mL(-1) Pb(II) level is 4.5 % (n = 6). The proposed method was successfully applied to determination of Pb(II) in environmental water and tea drinks samples with satisfactory recoveries in the range of 94-105 %.