COMPARISON OF INSTRUMENTAL METHODS FOR THE DETERMINATION OF TOTAL SELENIUM IN ENVIRONMENTAL-SAMPLES

Choosing the appropriate instrumental method for the determination of total Se in environmental samples is difficult, considering the wide choice of methods currently available. By use of a sediment matrix, an objective comparison is made between fluorimetry, hydride generation atomic absorption spectrometry (HGAAS), hydride generation inductively coupled plasma atomic emission spectrometry (HG-ICP-AES), hydride generation inductively coupled plasma mass spectrometry (HG-ICP-MS) and radiochemical neutron activation analysis (RNAA) methods, involving technical criteria such as detection limits, reproducibility, time taken for analysis and interferences. A novel flow injection (FI) system was constructed and adapted for AAS to improve the efficiency of HG systems and shows that the method of hydride sample injection can have a substantial influence on over-all performance. Consideration is given to the definition and use of the term limit of detection. The conclusions of the study are that fluorimetry, HGAAS and HG-ICP-AES will continue to be usefully employed for routine, laboratory analyses, although with the fluorimetric method, performance characteristics are inferior in comparison with those of more recent analytical techniques. The FI-HGAAS method is superior to the single sample HGAAS system. For samples of low Se concentration, HG-ICP-MS and RNAA methods are superior.