LUMEX Ltd. - RA-915+/PYRO-915

PRINCIPLE OF OPERATION

Direct atomic absorption mercury determination (without any pre-treatment procedures) in the samples with complex matrix (foods, vegetation, oil and its products, soils, sediments, various biological materials) is complicated by presence of organic compounds. When such samples are atomized much smoke is produced and practically in all cases the total absorption in the cell is out of the working range of the spectrometer. Using a spectrometer with background correction - Zeeman atomic absorption mercury spectrometer RA-915+ and a developed two-chamber catalyst atomizer (PYRO-915), the direct mercury determination problem is solved.

After inserting the sample in the first chamber of the atomizer it is heated up to 800 C (all mercury compounds are known to be dissociated at such temperatures). Less volatile mercury compounds are dissociated but more volatile species, e.g. mercury organic compounds, can leave the first chamber as compounds during warming up of the chamber. In addition presented organic compounds of the matrix originate much smoke and variously compounds, which are able to produce strong background absorption in the analytical cell. All products are transported from the first chamber to the second one by the carried gas (in our case it is air). The second chamber is continuously heated about 800 C. There, all mercury compounds are dissociated and smoke and interference compounds are burst producing mostly carbon dioxide and water. Zeeman corrector of the spectrometer eliminates the rest background absorption. The catalyst improves the efficiency of oxidation and dissociation in the second chamber.

FEATURES AND BENEFITS