Speciation of Chromium by Magnetic Solid Phase Microextraction Using an Activated Charcoal-Molybdenum (IV) Selenide-Magnetite Composite with Flame Atomic Absorption Spectrometric (FAAS) Detection.

A simple and sensitive magnetic solid phase extraction (MSPE) method was developed for the separation-preconcentration and speciation of Cr in water samples. The system is based on the adsorption of Cr (VI)-ammonium pyrrolidinedithiocarbamate (APDC) complex on the activated charcoal@MoSe2@Fe3O4 composite. Total chromium has also been determined after the conversion of Cr (III) to Cr (VI) by oxidation with KMnO4. Cr (III) was determined as the difference between the total content of the Cr and Cr (VI). For quantitative recoveries, the effects of solution pH, adsorbent amount, volume of the sample, ligand volume, eluent type, and volume and effect of foreign ions were investigated. The limit of detection and limit of quantification for Cr was 0.36 ng mL−1 and 1.19 ng mL−1, respectively. The procedure was applied for the determination and speciation of chromium in water samples. [ABSTRACT FROM AUTHOR]