Solid phase extraction of heavy metal ions in environmental samples on multiwalled carbon nanotubes

Multiwalled carbon nanotubes (MWNTs) were used as solid phase extractor for Cu(II), Cd(II), Pb(II), Zn(II), Ni(II) and Co(II) ions as ammonium pyrrolidine dithiocarbamate (APDC) chelates, in the present study. The influences of the experimental parameters including pH of the solutions, amounts of MWNTs, amounts of APDC, eluent type and volume, sample volume etc. on the quantitative recoveries of analyte ions were investigated. The effects of matrix ions of natural waters and some transition metals on the recoveries of the analyte ions were also examined in the model solutions. Tests of addition/recovery for analyte ions in real samples were performed with satisfactorily results. The detection limits (3 s) for the analyte ions were in the range of 0.30-0.60 μg l^-1. The concentrations of analytes in standard reference materials (NIST RM 8418 Wheat gluten, LGC 6010 Hard drinking water and NIST SRM 1515 Apple leaves) pretreated by the presented method were measured with FAAS and the analytical values were well agreed with the certified values and the reference values without the interference of major components. The presented method has been applied to the determination of analytes in food and environmental samples with satisfactory results.