Fast, green and effective chromium bio-speciation using Sepia pharaonis endoskeleton nano-powder.

The development of a fast, effective, simple and low-cost procedure for chromium speciation is an analytical challenge. In this work, a new and simple method for speciation and determination of chromium species in different matrices was developed. Sepia pharaonis endoskeleton nano-powder was used as an adsorbent for the dispersive micro-solid-phase extraction. Finally, the desorbed chromium was determined using a graphite furnace atomic absorption spectrometer. The experimental results showed that Cr(III) could be quantitatively extracted by the adsorbent, while Cr(VI) adsorption was negligible. Concentrated HSO and ethanol reduced Cr(VI)-Cr(III), and total chromium content was assessed as Cr(III). Then, the Cr(VI) concentration in the sample was calculated as the difference. The optimum conditions were obtained in terms of pH, adsorbent amount, contact time, and type, concentration and volume of eluent. Under the optimum conditions that involved the speciation of chromium ions from 25 mL of the water samples at pH 7.0 using 0.025 g of the adsorbent with contact time of 5 min, the method was validated in terms of linearity, precision and accuracy. The calibration curve was linear over the concentration range of 0.01-25.00 μg L for Cr(III). The obtained limit of detection for the proposed method was 0.003 µg L. The maximum adsorption capacity of the adsorbent was found to be 995.57 mg g. The proposed method was validated by the speciation of Cr(III) and Cr(VI) in different real water and wastewater samples with satisfactory results. [ABSTRACT FROM AUTHOR]