New modified cellulose nanoparticles for solid-phase extraction of some metal ions in biological and water samples

A preconcentration procedure for heavy metal ions in biological and water samples has been presented. The procedure is based on the sorption of Cu2+, Cd2+, Hg2+, and Pb2+ on cellulose nanoparticles modified with folic acid. The prepared adsorbent was characterized by FT-IR, SEM, TEM, and BET measurements. Potentiometric titration is used to prove the complexation between metal ions and the modified cellulose as well as to calculate the cation-exchange capacity of the sorbent. The influences of the analytical parameters including pH, amount of adsorbent, shaking time, temperature, conditions of desorption, and the effects of matrix ions were studied. Under the optimized conditions, the calibration curves for Cu2+, Cd2+, Hg2+, and Pb2+ were linear in the range of 2.7-200, 0.5-50, 0.37-150, and 10-300 mu g L-1, respectively. The detection limits (3s, n = 10) for Cu2+, Cd2+, Hg2+, and Pb2+ were 0.81, 0.15, 0.11, and 3.9 mu g L-1, respectively. The proposed method offers a preconcentration factor of 200 for all of the ions studied and an enhancement factor for Cu2+, Cd2+, Hg2+, and Pb2+ of 40.0, 30.8, 40.4, and 34.2, respectively. The accuracy of the suggested method was tested by analyzing spiked samples. The method was successfully applied to the determination of these metal ions in water and blood samples.