Comparison of the extractability of three organochromium(VI) complexes into four organic solvents

Abstract

The extractabilities of three chromium(VI) complexes into four extraction solvents were determined by flame atomic-absorption spectrometry with an air-acetylene flame using chromium acetylacetonate as a standard. The pH of a sample solution containing 50 µg of chromium was adjusted to a known value between 1 and 8. Next, sodium diethyldithiocarbamate, ammonium tetramethylenedithiocarbamate (ammonium pyrrolidinedithiocarbamate, APDC) or trioctylamine were added in a 500-fold molar excess over chromium. The extractabilities of chromium complexes into various volumes of isobutyl methyl ketone (IBMK), butyl acetate, ethyl acetate and isoamyl acetate were determined. The APDC complex showed excellent extractability into all solvents. It was easily extracted into both IBMK and isoamyl acetate, giving extractabilities of 93 ± 6 and 93 ± 3%, respectively, at pH 3. The results of replicate determinations produced a negative correlation coefficient between the extractability and the precision.