Determination of chromium by AAS using volatileβ-diketonate complexes

Summary

A new method is proposed for the determination of chromium, which is based on atomizing the volatile phase, generated from itsβ-diketonates, in a silica tube. For this purpose, an electrically-heated volatilization system was designed, in which the chelate is injected and volatilized, and then carried by nitrogen to the silica tube, which is heated with an air-acetylene flame. The system parameters were optimized and the analytical characteristics established, the following values being obtained: characteristic mass (measuring area under peak) 0.15 ng, reproducibility (expressed as the relative standard deviation) 5.6%, and linearity up to 25 ng. The results obtained were compared with those found when atomizing solutions ofβ-diketonates in an air-acetylene flame and in a graphite furnace. Atomization of chromiumβ-diketonates (after first volatilizing them) increases the sensitivity 54-fold as compared with the nebulization of aqueous solutions of dichromate with atomization in the flame.