Is microwave assisted digestion a suitable preparation method for Pt determination in biological samples by adsorptive cathodic stripping voltammetry (ACSV)?

In: Analytica Chimica Acta, Jg. 635 (2009) ; Nr. 1, S. 53-57
ISSN: 0003-2670
Zeitschriftenaufsatz / Fach: Biologie
Abstract:
The occurrence of Pt in environmental matrices is increasing since the introduction of automobile catalytic
converters. Given that Pt is bioavailable and causes biological effects in plants and animals, respective
biomonitoring programs are in high demand. But the analytical methods for conducting such programs
have not yet been sufficiently established. Therefore, a study was carried out to develop a microwave
digestion of biological samples, which allows a rapid determination of Pt by adsorptive cathodic stripping
voltammetry.
A high pressure microwave system was used and the digestion was performed in HNO3 and HCl. After
digestion the HNO3 was evaporated with a microwave assisted vacuum concentration set. The study
resulted in a procedural detection limit of 37.5 ng L−1 and a relative standard deviation of 18%. A recovery
study resulted in a Pt loss below5%. The microwave assisted evaporation ofHNO3 performed satisfactorily
and up to 500mL of the sample solution could be used for the voltammetric measurements without any
effect on the peak heights. A direct comparison of Pt concentrations conducted after microwave digestion
and digestion by high pressure ashing showed similar values. However, these promising results were not
persistent throughout the repeated analysis using the same Teflon vessels. The vessels did not endure the
harsh conditions and due to aging processes the Pt loss consistently increased until Pt determination in
environmental relevant concentrations became impossible. Quartz vessels could not be employed as an
alternative to the Teflon vessels, due to a lack of compatibility with the vacuum concentration system.
Consequently, the results of this paper showthat there is a need for further development of more resistant
Teflon materials.

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