Sulfonated metal organic framework loaded on iron oxide nanoparticles as a new sorbent for the magnetic solid phase extraction of cadmium from environmental water samples

A sulfonated metal organic framework loaded onto iron oxide nanoparticles (Fe3O4@MOF-235(Fe)-OSO3H) was used as a new sorbent and a magnetic solid phase extraction (MSPE) method was developed for the separation and preconcentration of cadmium prior to its determination by flame atomic absorption spectrometry. The Fe3O4@MOF-235(Fe)-OSO3H composite was characterized by thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD) analyses. The influence of the effective parameters such as solution pH, type, concentration and volume of the eluent, amount of the sorbent, sample volume and the extraction time on the extraction of cadmium was investigated and optimized. Under the optimized conditions, the limit of detection and the enrichment factor of the method were found to be 0.04 mg L-1 and 195.0, respectively. The inter-day and intra-day relative standard deviation (RSD) for five replicate measurements at 2.5 mg L-1 Cd(II) were 1.0 and 3.6%, respectively. The method was successfully applied to the extraction and determination of cadmium in environmental water samples.