RECENT ADVANCES IN ABSOLUTE ANALYSIS BY GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY

Some results are presented applying the STPF technique in GFAAS to the solution of the main problems obstructing progress toward absolute analysis, namely, elimination of matrix interferences, stabilization of calibration and theoretical calculation of sensitivity (characteristic masses,m0). Recent advances in the calculation of the values of m0 for 35 elements are discussed in detail. Compared with earlier publications, the present calculations make use of improved values of some physical constants (f,α,γ') and include the effects of the adjacent lines and Doppler line width in the light source. The largest discrepancy, always less than a factor of two between the calculation and experiment, is observed for Cs, Li and Rb, and is most probably due to partial ionization of the atoms. A study of the degree of ionization of Ba supports this assumption. The average value of m0 cal/ m0 exp for the remaining group of 32 elements was found to be 0.85 ± 0.10. No depressive effect was observed on the sensitivity of determination of the less volatile elements due to the spatial non-isothermality of the furnace. Theoretical calculations of the relative sensitivities in a.c. Zeeman AAS have been carried out. Satisfactory agreement was obtained with experiment. © 1990.