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As distinguished from other toxic pollutants, heavy metals can accumulate in living tissues. Among the elements that currently need to be determined in biological samples, chromium is important in view [...], In this study, a simple dispersive liquid--liquid microextraction method based on task-specific ionic liquids was applied for highly sensitive determination and speciation of chromium (III, VI) in human blood by electro-thermal atomic absorption spectrometry. In this method, a mixture containing of 1-(3-aminopropyl)-3-methylimidazolium hexafluorophosphate [APMIM][[PF.sub.6]] and 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][[BF.sub.4]] (extracting solvent), acetone (dispersant) and TX-100 (anti-sticking agent) were added to Cr(VI) solution in 1 mL blood samples that was extracted by binary mix ionic liquids. For extraction of Cr(VI) anions, the binary mix ionic liquids ([APMIM][[PF.sub.6]], [BMIM][[BF.sub.4]]) and acetone were used as extracting and dispersant solvent, respectively. Total chromium was simply obtained by oxidation of Cr(III) to Cr(VI) by [H.sub.2][O.sub.2] solution, and Cr(III) is calculated by difference between total chromium and Cr(VI). Under the optimal conditions, the calibration graph and limit of detection were 0.02-0.9 µg/L and 5 ng/L, respectively. The developed method was applied successfully to determination and speciation Cr (III, VI) in human blood samples. Keywords: chromium (III, VI), speciation, task-specific ionic liquids, dispersive liquid--liquid microextraction, electro-thermal atomic absorption spectrometry DOI: 10.1134/S1061934815120072

A 2-furaldehyde-selective PVC-membrane electrode is designed based on the host-guest interaction between tetrabenzyl ether Calix[4]arene, as an ionophore, and a lipophilic hydrazone derivative generated in situ from reaction of 2-furaldehyde and Girard's reagent T. At a pH of 9.2, the electrode exhibits a Nernstian response over the 2-furaldehyde concentration range of (5.0 x [10.sup.-5]) - (1.0 x [10.sup.-1]) M. The electrode has found to be chemically inert and of adequate stability with a response time of 15 s with a good reproducibility ([+ or -] 0.2 mV) and can be used for a long working lifetime. In order to improve the minimum detectable concentration of 2-furaldehyde, further studies have been performed using a coated graphite electrode and coated platinum and gold disks. Some analytical aspects of adsorptive square wave voltammetry have also been presented in order to elucidate the adduct formation between 2-furaldehyde and Girard's reagent T. The interfering effects of some [Na.sup.+], [K.sup.+], [NH.sub.4.sup.+], formaldehyde, 5-hydroxymethyl 2-furaldehyde (HMF), excess of Girard's reagent T and organic solvents such as isopropyl alcohol and N,N-dimethylformamide on the sensor's response have been studied. The viability of using the electrode for the trace determination of 2-furaldehyde in several Iranian oil refinery wastewater samples is also demonstrated. The results obtained from the developed method for real samples are compared with those from UV-spectrophotometric and high-performance liquid chromatographic experiments.