240FS AA - Atomic Absorption Systems

In flame atomic absorption spectroscopy (AAS), the sensitivity is defined as the concentration of analyte that produces 1% absorption signal (0.0044 Abs). This proved to be a very valuable diagnostic concept. When instrumental conditions were set correctly, this value for sensitivity was very predictable. As graphite furnace AAS deals with an absolute amount of analyte, it seems preferable that mass be substituted for concentration. By analogy with flame AAS, it is defined as the amount in mass units that produces 0.0044 integrated absorbance (1% absorption). Characteristic Mass In 1955, Alan Walsh (1) noted that graphite furnace AAS could be an absolute method. In 1984, Walter Slavin (2) proposed the concept of characteristic mass in graphite furnace, defined as the absolute mass of analyte giving a peak area of 0.0044 absorbance. In 1986, Boris L'Vov (3) published a comparison of the theoretical and calculated characteristic mass for 40 elements using integrated absorbance signals. If the results showed some limitations of the absolute method, the experimental characteristic mass became a tool to control/ check the day to day operation of a given GFAAS instrument and the applied methodology. The Stabilized Temperature Platform Furnace (STPF) concept (6), developed by Slavin in 1981, demonstrated that the characteristic mass can be relatively independent of the sample matrix. Theoretical characteristic masses were calculated with the model developed by L’Vov in 1986 (3). This correlation can be used to optimize operating conditions and steps of the temperature program to give an experimental mass close to theoretical characteristic mass.