Separation/preconcentration and speciation of chromium by syringe to syringe dispersive liquid phase microextraction-flame atomic absorption spectrometery

Chromium exists in nature at very low concentrations and predominantly in two oxidation states of chromium (III) and (VI) which have different toxicities and biochemical reactivity. Cr(III) is considered as an essential trace elemental species that controls glucose, lipid and protein metabolism in mammals. Cr(VI) is a highly toxic species for both plants and animals as well as being potentially carcinogenic [1]. Chromium (VI) is a danger to human health, mainly for people working in the steel and textile industries or smoking tobacco. So, determination of trace amounts of chromium species in water and biological samples is essential [2].A syringe to syringe dispersive liquid phase microextraction combined with flame atomic absorption spectrometry has been developed for separation, preconcentration, and speciation of chromium in real samples. The speciation of chromium was based on the formation of a complex between Cr(III) and 8-hydroxy quinolone dissolved in isobutyl methyl ketone. Total chromium was determined after reduction of Cr(VI) to Cr(III) with hydroxylamine. The variable affecting the preconcentration were optimized by the univariable method. Under the optimized conditions, the linear range, enhancement factor, limit of detection and limit of quantification were found to be 5.0-250.0 µg L-1, 33, 0.094 µg L-1 and 0.313 µg L-1, of Cr(III), respectively. The method was successfully applied to the determination of chromium species in tap water, spring water, Caspian sea water and brown sugar