Selective extraction of Cu+ and Cu2+ ions from mushroom and lichen samples prior to analysis by micro-volume UV-Vis spectrophotometry: Application of a novel poly (SMIm)-Tris-Fe3O4 nanocomposite

In this study, a novel poly (SMIm)-Tris-Fe3O4 nanocomposite was prepared for selective extraction of Cu+ and Cu2+ ions by ultrasound assisted-cloud point extraction (UA-CPE). The nanocomposite was characterized by analysis of ATR-FT-IR, H-1 NMR and XRD. After optimization of the extraction conditions, the copper ions were independently detected against sample blank at 347 nm by micro-volume UV-vis spectrophotometer. Under the optimal conditions, good linear relationship was obtained in the ranges of 0.3-150 and 10-350 mu g L-1 for each ion at pH 7.0 and pH 5.0, respectively, with a better regression coefficient than 0.992. The method detection limits, accuracy and precision were 0.095 and 3.03 mu g L-1, 91.5-96.0 % and 93.0-98.5 %, and 2.5-4.5 and 3.8-7.1 % (n:5, 25 and 100 mu g L-1) for Cu+ and Cu2+ ions, respectively. A preconcentration of 70-fold was obtained from 35-mL of sample. After validation, the method was successfully applied to determination of total Cu levels in lichen and mushroom samples after pre-reduction at pH 7.0, and the recoveries in the range of 90-96 % were obtained by two calibration approaches after spiking with 10 mu g L-1. The results were also statistically compared with those obtained by FAAS analysis to ensure accuracy and precision.