An open microwave digestion of oxide materials continuously analyzed by ICP emission spectrometry

A device for microwave digestion in an open system was designed, with which a slurry automatically produced from solid sample powders can be processed continuously and then be transported directly into the ICP spectrometer by an online method. The success of this procedure is dependent to a high degree on the behavior of the material to be analyzed and the instrumental device used. In principle, it can be easily installed in a laboratory by combining single units like a mill, a pump, a microwave oven, and an ultrasonic bath in front of an ICP spectrometer. As examples, converter sludge and sinter were processed. In contrast to the sludge, the sinter material was difficult to homogenize sufficiently well. This led to recovery problems, especially for oxides of Si, Al or Ti being separated from the matrix by long-time milling. To overcome the blocking of valves, an open microwave digestion system is applied here (as usual by acid attack). Furthermore, the ICP source is able to excite the particles of a slurry much more efficiently than any other flame. The sufficient results obtained for the online method described here showed it to be a fast method for routine analysis.