engleski

Determination of chromium (VI)and chromium (III) in liquid environmental samples by EDXRF method

A rapid, sensitive and selective procedure for determination of Cr(III) and Cr(VI) in environmental and industrial liquid samples via preconcentration with ammonium pyrrolidine dithiocarbamate (APDC) and determination by means of the EDXRF was described. The effect of pH in the range of 3-11 on the recovery of Cr(III) and Cr(VI) has been investigated separately and in combination of these two species. The influence of organic matter, carbonate species and elements V, Mn and Fe on the recovery of each chromium specie (separately/in combination) over whole pH range was also tested in order to simulate condition occurring in natural waters that usually contain certain amount of dissolved organic matter and carbonate ions. Characteristic of Cr(VI) and Cr(III) to create complexes with APDC in the different pH ranges makes possible to separate those two species. It was found that Cr(VI) create complexes with APDC (separately/in combination) only in the pH range from 3 to 5 with quantitative recovery (app. 98%) at pH 3, but there was no recovery of Cr (III) at that pH. On the contrary, pH range for Cr (III) - APDC complex formation (separately/in combination) was from 6 to 11 with quantitative recovery at pH 11. Zero recovery of Cr (VI) was obtained in that pH range. All created complexes of Cr(VI) and Cr(III) with APDC were characterized by IR spectroscopy.

Cr (VI) ; Cr(III) ; APDC ; EDXRF ; preconcentration

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