Determination of chromium (III) and chromium (VI) by ammonium pyrrolidine dithiocarbamate-methyl isobutyl ketone-furnace atomic absorption spectrometry

Abstract

This paper explores the feasibility of directly complexing both Cr(III) and Cr(VI) by ammonium pyrrolidine dithiocarbamate (APDC) at room temperature, extracting these subsequently into methyl isobutyl ketone (MIBK) and determining the individual Cr species in the MIBK phase by GFAAS (Graphite Furnace Atomic Absorption Spectrometry). The solution parameters studied include: pH of the aqueous phase, concentration of APDC, concentration of potassium hydrogen phthalate (PHP) buffer, and length of time needed for complete extraction. These studies showed that, by careful optimization of the concentrations of APDC, PHP, pH and extraction time, the APDC-MIBK system could be used to: (i) selectively separate Cr(VI) from Cr(III); and (ii) simultaneously extract Cr(III) and Cr(VI) at room temperature without the need to oxidize Cr(III) or Cr(VI).