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1 Wiadomości Chemiczne

1 2002

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Rozdział i oznaczanie Cr(III) i Cr(VI) w próbkach środowiskowych

Kalembkiewicz J., Sočo E.

Wiadomości Chemiczne

2002

[Z] 56, 9-10

855-873

Learning the biochemical properties of Cr(III) and Cr(VI), especially mutagenic activity of Cr(VI) caused quick development of investigation of Cr speciation in environmental samples. Complex composition of matrix, possible course of the redox reaction of Cr and its low concentration often make difficult application of direct methods of determination of Cr(III) and Cr(VI). The investigation of speciation of Cr by preliminary separation of Cr(III) and Cr(VI) and their preconcentration eliminates a series of analytical problems and creates a possibility of Cr detection with various techniques, also in coupled systems. The Cr(III) and Cr(VI) in systems HPLC-ICP-AES, HPLC-ICP-MS, HPLC-AAS, HPLC-FI-AAS, HPLC-UV were separated, preconcetrated and determined. Independently from HPLC also other chromatographic techniques were used. Ion-exchange was applied mainly to separation of Cr(III) and Cr(VI), as well as to separation of Cr(VI) or Cr(III) [58] from other ions. To separation of Cr(III) and Cr(VI) there were applied: sorption, biopolymer coating and bioaccumulation. Separation and preconcentration of Cr(III) and Cr(VI) is possible by applying solvent extraction. To extraction of Cr(III) and Cr(VI) and their separation were applied amines, ammonium salts and non-ammonium salts, amine oxides, carboxylic and hydroxycarboxylic acids and other reagents. To separation and preconcentration of Cr(III) and Cr(VI) there are proposed ion-exchange membrane, electrophoresis, precipitation and co-precipitation and other methods of separation. Determination of Cr(III) and Cr(VI) without preliminary separation is possible in environmental samples, in which at the stage of preparing to analysis or during analysis the redox reactions with participation of Cr do not proceed. For direct determination of Cr(VI) spectrophotometric method (UV) is applied with the use of 1,5-diphenylcarbazide, methylene blue, iodonitrotetrazolium chloride, tetrazolium violet , 5-Br-PADAP, dibenzyl-dithiocarbamate, rhodamine 6G, nitrotetrazolium blue and neotetrazolium chloride, whereas for determination of Cr(III) there were applied: EDTA, triphenylmethane reagents, PAR and PAN. For direct determination of Cr(VI) or Cr(III) polarography and others methods were applied.