ABSOLUTE ANALYSIS IN ELECTROTHERMAL ATOMIZATION ATOMIC-ABSORPTION SPECTROSCOPY - AN ATOMIZATION SYSTEM FOR CONFINING ALL THE ATOMS INJECTEDIN THE OPTICAL BEAM

The apparatus presented in this paper is able to simultaneously confin e all the atoms injected into the atomizer within the optical beam. As a consequence, during the time interval fulfilling this condition, th e absorbance is constant. Experimental absorbance vs time curves, with Cd as analyte, show a constant value for more than 0.2 s. The curve s hapes are in agreement with those theoretically derived for pure diffu sion. This finding should lead to a method for absolute analysis that is more accurate than the methods used in ETA-AAS up to now. In fact, with this approach, one has to measure a constant signal while in the case of area measurements one has to integrate a signal that exponenti ally decays toward the baseline value. Data presented in this paper re fer to the most volatile elements (Cd, Hg and Pb) in simple matrices. The possibility of extending the presented method to complex matrices and less volatile elements is dependent on the availability of both a more powerful power supply system and well-suited atomizer design.