Direct determination of aluminium in natural waters by laser stepwise photoionization

Abstract

The development of new, highly sensitive, methods of analysis of microelements and aluminium, particularly in natural waters, is important because: (1) aluminium, one of the most important elements in the lithosphere, is used in lithology and geochemistry of ocean as an indicator of terrigenous runoff; and (2) there are data^1,2 relating aluminium dissolved in sea-water to certain biological processes. However, the sensitivity of conventional analytical methods in most cases is insufficient for a direct determination of aluminium dissolved in sea and ocean waters^3,4. Modern laser methods of single atom detection (see refs 5, 6) seem promising for this purpose due to their high detection efficiency; of particular interest is the method of laser stepwise photoionization of atoms^7,8. We describe here a new highly sensitive analytical method based on this technique which involves thermal atomization of the sample in vacuum and detection of the element atoms through their stepwise excitation to a Rydberg state and following ionization by electric field pulse.