Facile synthesis of magnetic MWCNT functionalised 8-hydroxyquinoline: characterisation and application for selective enrichment of cadmium ions in food samples

A simple and efficient approach for preparing modified magnetic multi-walled carbon nanotubes (MMWCNT) with 8-hydroxyquinoline was developed. This short-cut method has reduced the contact time of modification from 2 days to 10 hours. The properties of MMWCNT modified 8-hydroxyquinoline were characterised by scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and Fourier transform infrared spectrophotometer (FT-IR). This adsorbent was found to be a new, selective, low-cost and high capacitance for enrichment of cadmium in solid-phase extraction (SPE). In addition, based on the easily separated modified MMWCNT from the aqueous solutions with the help of an external magnet, no filtration or centrifugation was needed. The variables of interest in the SPE, such as pH, ionic strength, extraction time, desorption time, type and volume and concentration of eluent, were optimised. The calibration graph was linear over the range of 0.42-127 mu gl(-1). The limit of detection was 0.12 mu gl(-1) and the relative standard deviation of 2.25% at 30 ng ml(-1) Cd(II) ions was obtained (n = 8). The preconcentration factor and adsorption capacity of the sorbent were 160 and 60.2 mg g(-1) respectively. Finally, practical applicability of the developed adsorbent was confirmed by preconcentration of Cd(II) ions from water, vegetable and food samples.