Biosorption using chitosan thiourea polymer as an extraction and preconcentration technique for copper prior to its determination in environmental and food samples by flame atomic absorption spectrometry: Synthesis, characterization and analytical applica

The present work describes the synthesis and use of the chitosan thiourea polymer (CT polymer) as a novel biosorbent for copper preconcentration prior to its determination by flame atomic absorption spectrometry (FAAS). CT polymer submitted in the present study was synthesized by the direct reaction between chitosan isolated from penaeus monodon chitin and ammonium thiocyanate, then the chemical structure and morphology of polymer were investigated by spectroscopic measurements, thermal analysis, X-ray diffraction (XRD) and scanning electron microscope (SEM). The results of SEM and XRD show that the prepared CT polymer has rough and hard surface with pores and nanofibers structure in the α-form. The height equivalent to the theoretical plates (HETP), the plates number (N), LOD and LOQ of CT polymer packed column were calculated to be 0.10 ± 0.04 mm, 100 ± 2.02, 0.3 μg L−1and 0.99 μg L−1, respectively. The developed column was employed in combination with FAAS for the analysis of copper in a certified reference material (NRCC-SLRS-4 Riverine water), potato, tea, and rice. Furthermore, the structure of the copper complex with CT polymer was proven with the aid of different spectroscopic and magnetic measurements.