Spider-web-like chitosan/MIL-68(Al) composite nanofibers for high-efficient solid phase extraction of Pb(II) and Cd(II)

The authors describe the synthesis of spider-weblike chitosan/MIL-68(Al) composite nanofibers, their application to fast solid phase extraction (SPE) of trace levels of Pb(II) and Cd(II), and their quantitation by ICP-OES. The composite nanofibers were characterized by X-ray diffraction, scanning electron microscopy, N-2 adsorption-desorption experiments and FT-IR. The pH value of sample solutions, amount of sorbent, eluent concentration and type and volume of the eluting solvent were optimized using factorial experimental design. Under the optimum conditions, the detection limits are 0.16 mu g L-1, and linear ranges extend from 0.5-50 mu g L-1 for both Pb(II) and Cd(II). The intra-day relative standard deviations (RSDs) of <3.8% and inter-day RSDs of <4.3% are quite acceptable. The accuracy of the method was tested by the analysis of the certified reference material IAEA-407 and by recovery measurements on spiked real samples (phylum, gastropoda, Trochus erythraeus mollusks) which demonstrated the good performance of the method for SPE and determination of Pb(II) and Cd(II) ions.