A procedure is described for the analysis of individual atmospheric particles using an automated analytical scanning electron microscope (AASEM). The procedure incorporates a novel automatic video thresholding method that is essential for long-term unattended analysis of particles as small as 1 (μm in diameter. The procedure is evaluated by using particle dispersions prepared from USGS standard rock powders. Mineral particle types were identified by using cluster analysis. Typical precision of ±10% for major mineral types and ±20% for minor mineral types were determined from replicate analyses. The results of a chemical mass balance between individual particle analyses and bulk chemical compositions of the standard rock powders indicate a precision of better than ±15% for most elements. The accuracy of the procedure, when normalized to SIO2, ranges from 1 % to more than a factor of 3. Large discrepancies for some elements are due to errors in particle volume calculations and problems associated with analyzing minor mineral types.
ASJC Scopus subject areas
- Analytical Chemistry