A graphene oxide based poly(2,6-diaminopyridine) composite for solid-phase extraction of Cd(II) prior to its determination by FAAS

The authors describe the preparation of a graphene oxide based poly(2,6-diaminopyridine) composite by in-situ polymerization. The material was characterized by Fourier transform infrared spectrometry, powder X-ray diffraction and scanning electron microscopy. The composite was placed in a column and used for solid phase extraction (SPE) of Cd(II) ions from water samples. The adsorbed Cd(II) was then eluted with HCl and injected into a flame atomic absorption spectrometer. The effects of pH values, volume and flow rate of sample, and the kind, volume and concentration of eluent were optimized. The calibration plot for the assay is linear in the 2 to 100 mu g.L-1 Cd(II) concentration range. Other figures of merit include (a) a 0.47 mu g.L-1 limit of detection, (b) a relative standard deviation of 1.6% (for n = 7; at 20 mu g.L-1 of Cd(II)), and (c) a preconcentration factor of 50. The method was validated by analyzing the certified reference material NIST SRM 1643f and spiked real samples. The method was successfully employed to the determination of Cd(II) in tap, river, seawater and wastewater samples.