Application of multiwalled carbon nanotubes modified by diphenylcarbazide for selective solid phase extraction of ultra traces Cd(II) in water samples and food products.

A novel sorbent for separation of cadmium ions was prepared by functionalizing multiwall carbon nanotubes with diphenylcarbazide and underutilised to develop a solid-phase extraction method to separate and concentrate trace amounts of cadmium ions from some real samples by flame atomic absorption spectrophotometry measurements. The optimum experimental conditions such as pH, flow rates, type and the smallest amount of eluent for elution of cadmium ions, break through volume and effect of coexisting ions on the separation and determination of cadmium ions were evaluated. In the proposed method, the extraction efficiency for cadmium ions were greater than 97% and limit of detection (LOD) was 0.05 ng mL(-1). The preconcentration factor was 360 for cadmium and the relative standard deviation (RSD) of the method was 2.4%. The adsorption capacity of the modified MWCNT was 86 mg g(-1) for cadmium ions. Validation of the outlined method was performed by analysing certified reference material soil (NCS DC 73323). The practical applicability of the developed sorbent was examined in some real samples.