Effect of Stray Light on Characteristic Mass in Zeeman Graphite Furnace Atomic Absorption Spectrometry

The characteristic mass (m₀), the effective stray light (α), the Zeeman rollover absorbance (A_r), and the Zeeman sensitivity ratio (R) were studied systematically as a function of lamp current and slit width. The effective stray light, α, was considered to be the sum of all effects that either are different sources of stray light or behave like stray light. Mathematical expressions are presented to describe the relationships between m₀, R, α, and A_r. The characteristic mass, m₀ is directly related to the effective stray light and the Zeeman sensitivity ratio. R. The Zeeman rollover absorbance, A_r, is a quantitative measure of the effective stray light. By taking α and R into account, a stable characteristic mass value, ^cm₀ was obtained for copper, silver, thallium, and chromium for different lamp currents and slit widths. This gave rise to a new concept "the corrected characteristic mass." Without correction for these effects, the relative standard deviations (RSDs) of measured characteristic mass values, m₀, were 8% for Cr, 19% for Tl, 20% for Cu, and 26% for Ag, for a wide range of currents and/or slit widths. After correction for the effects of rs and R, the corrected characteristic masses, ^cm₀, were stable with an RSD of only 4% for Cu, Cr, and TI, and 7% for Ag.