EFFECT OF SAMPLE INJECTION MODES ON RESIDUE DEPOSITS IN GRAPHITE-FURNACE ATOMIC-ABSORPTION

Two modes of liquid sample deposition into the graphite furnace were studied: injection of a single droplet by micropipet and injection of an aerosol spray. The deposition modes were compared with respect to structure of the deposit, corrosive effects on the graphite, and analytical data for Se with Ni matrix modification. Examination of the deposits by scanning electron microscopy revealed that, contrary to previous assumptions, deposition of an aerosol resulted in solids with larger crystals than that produced by micropipet injection (under the conditions used in the study). Corrosion of the surface of the graphite tube was more severe in general with aerosol injection. Analytical data demonstrated that deposits with larger crystals resulting from aerosol injection produced increased sensitivity for Se under the conditions of the study.