The influence of a temperature ramp on the absorbance in graphite furnace atomic spectroscopy has been investigated with the use of a computer simulation of the absorption process. For increasing temperature, the absorbance will increase for low values of the damping constant at constant
pressure and all values of the damping constant at constant volume. For large values of the damping constant at constant pressure (the presumed real situation), the absorbance decreases with increasing temperature due to the narrowing of the collisional profile. Hyperfine structure diminishes
the change in absorbance within limits. The evaluation of the number density of analyte for temperatures (times) other than the peak maximum temperature could be in error if the peak maximum absorbance of a GFAAS peak is used to derive the number densities at the other temperatures. In effect,
the relative absorbances on the peak in GFAAS are not totally representative of the relative atom release and removal peak. The presence of multiple ground states can, under certain circumstances, improve the absorbance-atom density relationship between the peak maximum absorbance and other
absorbances on the peak. The temperature ramp has no deleterious effect on the analytical capabilities of GFAAS when the effect of temperature on absorbance is considered.
Department of Chemistry, North Dakota State University, Fargo, North Dakota 58105
Publication date: September 1, 1985
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