The photochemical process of UV oxidation represents a promising alternative for the decomposition of dissolved organic carbon (DOC) in liquid samples. This technique uses the synergistic action of UV light in combination with a chemical oxidiser (e.g. H2O2) to mineralise interfering organic compounds converting it almost completely to CO2, H2O, and inorganic salts. Advantageous is mainly the low acid demand, followed by the elimination of a potential source of contamination and an improvement of the detection limit. Until now, UV instrumentation, especially developed for the purpose of sample preparation, was only capable of decomposing sample matrices of low organic content due to the limited maximum reaction temperatures of 65-90°C. In this project we develop a novel, microwave-assisted, high-temperature UV digestion procedure for the accelerated decomposition of interfering DOC prior to trace element analysis of liquid samples. The technique is based on a closed, pressurised, microwave digestion device. Generation of UV irradiation is not achieved by a single source as in batch devices, instead a multiple immersion system is applied. Appropriate electrodeless discharge lamps operated by the oscillating microwave field distributed within the oven cavity were developed in-house. This system allows maximum reaction temperatures up to 250-280°C, resulting in considerably increased degradation rates.
|Effective start/end date||1/04/99 → 31/03/03|
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