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Volume 46, Number 6
(November - December 2001) |
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Volume 46, Number 6
(November - December 2001) |
Critical Evaluation of the Effectiveness of Nitric Acid Oxidizing Systems: Pressurized Microwave-Assisted Digestion Procedure
by Henryk Matusiewicz
Technical University of Poznan, Department of Analytical Chemistry, 3 Piotrowo Street, 60-965 Poznan, Poland
Key words:
The possibilities of enhancement of a medium-pressure microwave-assisted
digestion system for sample preparation in trace element analysis of biological
material was investigated. Based on optimal digestion conditions for oxidizing
systems with nitric acid, different digestion procedures were examined
to minimize residual carbon. The substitution of nitric acid and the addition
of hydrogen peroxide and ozone to nitric acid was evaluated. The residual
carbon content of the digestate was determined coulometrically. Addition
of hydrogen peroxide during organic oxidation reactions does not lower
the dissoleved carbon in the solution. Ozone was tested as a additional,
potentially non-contaminating, digestion/oxidation system to the nitric
acid used in the sample preparation method. The digestion efficiency of
an optimized nitric acid system was improved by 13% by adding oxidizing
agent like ozone.
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