Analytical Performance of New Mixed Oxide (SiO2/TiO2/ZnO)-Based Sorbent for Development of a Reliable Mechanized Enrichment System for Copper Determination in Water and Food Samples

In the present study, a new composite material (SiO2/TiO2/ZnO) for copper preconcentration in water and food samples was evaluated. The sorbent was characterized by scanning electronic microscopy (SEM), Fourier transform infrared spectrophotometry (FT-IR), textural data analyses, energy dispersive X-ray fluorescence (EDXRF) and X-ray diffractometry (XRD). The on-line preconcentration and visible spectrophotometric determination was based on loading 20.0 mL of sample at pH 7.0 through 50 mg of sorbent at a flow rate of 6.4 mL min(-1). A fixed volume of 0.3 mL of 0.5 mol L-1 HNO3 elutes copper ions, in which react with 0.3% (m/m) diethyldithiocarbamate (DDTC) whose complex formed (Cu(DDTC)(2)) is monitored at 452 nm. The selectivity of sorbent has been examined by assessing the effect of interfering ions. The proposed method provided linearity ranging from 20.0 to 230.0 mg L-1 (r = 0.998), preconcentration factor of 35.9 and limit of detection of 5.6 mg L-1. Water and food samples were successfully analyzed by proposed method and the accuracy was checked by analysis of certified reference materials of protein and liver of fish.