Abstract
A trace amount of chromium(VI) was extracted as diethyldithiocarbamate from (1001000) ml of sea water into (1030) ml of methyl-iso-butyl ketone, and determined by atomic absorption spectrophotometry with an acetylene-air flame or a graphite furnace.
Various analytical parameters for the measurements of chromium by the flame and the flameless methods were examined. When the extraction was carried out at pH 4, the interference of coexisting chromium(III) was eliminated. The optimum concentration of sodium diethyldithiocarbamate in the aqueous phase was found to be 2.0×10-3 M for the extraction of 500 ppb of chromium(VI). Calibration curves were linear and the sensitivities were 0.4 ppb of chromium (VI) for 1% absorption using the flame method and 0.02 ppb using the flameless method when 1000 ml of aqueous and 30 ml of organic layers were used. No serious interference was observed when 1.0 ppb of chromium(VI) was determined in the presence of 10 ppb of Sr(II), Cu(II), Pb(II), Zn(II), Cd(II), Hg(II), Ni(II), As(III), Mn(II), Co(II), Be(II), Al(III), Fe(III), Mo(VI).
The proposed method was applied to the determination of chromium(VI) in artificial sea water and several actual sea water samples. When known amounts of chromium (VI) was added to the sea water samples, the chromium(VI) was recovered satisfactorily.
