FAAS Determination of Micro-amount of Zinc in Ground Surface Water after Extraction with Ionic Liquid

An ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (［Bmim］PF6), was synthesized, and used to extract Zn(Ⅱ) from water sample. Three mL of 10 g·L-1 EDTA solution and 5 mL of the ionic liquid were added to 500 mL of water sample, and the mixture was shaked for 5 min. The ionic liquid phase was separated and back extracted with 10 mL of 1.0 mol·L-1 HCl, in which the Zn(Ⅱ) content was determined by FAAS. Linear relationship between values of absorbance and mass concentration of zinc was obtained in the range of 0.005-0.02 mg·L-1, with detection limit (3σ) of 0.75 μg·L-1. The proposed method was used in the analysis of surface water, giving values of recovery in the range of 85%-110%.