Drying furnace atomic spectroscopy

Figure 11.14 A typical time-temperature profile for graphite-furnace atomic absorption spectroscopy 1, drying 2, ashing 3, atomization 4, cleaning 5, cooling. From Dean, J. R., Atomic Absorption and Plasma Spectroscopy, ACOL Series, 2nd Edn, Wiley, Chichester, UK, 1997. Reproduced with permission of the University of Greenwich.

The air-dried spiked filters were digested and analyzed for their cadmium content by flameless atomic absorption spectroscopy using a heated graphite furnace atomizer following the procedure described in Section 3. A five-fold dilution of the spiked filter samples at 2 times the Action Level TWA was made prior to their analysis. The 0.05 to 20 ng/mL cadmium standards were used in the analysis of the spiked filters. 

The process starts with the preparation of polymer solutions, for instance, polyvinyl alcohol (PVA), and metal compounds, for instance, 3d-metal chlorides. Afterwards, the solutions with a certain concentration are mixed in the ratio PVA-metal chloride equals to 20 1-1 5 (better 5 1). Then the prepared solutions are dried till they obtain gel-like colored films with further temperature elevation up to 100°C. The films obtained are controlled by spectral photometry, and also with help of transmission optical microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. When the film color changes to black, the films are heated in the furnace according to the following program 100-200-300-400°C. As a result, the dark porous semiproduct with many microcracks is formed, that is milled in spherical or jet mill. The nanopowder obtained is steamed and dispersed in hot water. After filtration, the powder is dried and tested with the help of Raman spectroscopy. X-ray photoelectron spectroscopy, transmission electron microscopy and electron microdiffraction. 

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