Anomalous curving of Arrhenius plots for data obtained from electro-thermal vaporization at atmospheric pressure

Abstract

Arrhenius plots are often used in electrothermal atomization atomic absorption spectroscopy (ETA-AAS) to obtain activation energies ( E a ) of vaporization processes. However, these plots are often nonlinear, and the exact cause of the curvature is not clear. This phenomenon has been attributed to multiple generation functions, diffusion of atoms through the graphite walls, changes in the size of the generating particles, changes in the surface coverage and interferences of the removal function with the supply function. This paper examines several other possibilities using computer simulations on a micro-computer. These possibilities include the effects of diffusion, errors in the assumed order of the reaction and small systematic errors. These can create curving very similar to that observed in typical ETA-AAS and should be considered before assigning the curvature to other chemical or physical properties of the system.