Effect of Salt Matrices on the Atomization of Cadmium and Manganese in Graphite Furnace Atomic Absorption Spectrometry

Abstract

The effects of NaCl, CaCl₂ and MgCl₂ salts on the atomization process of Cd and Mn elements in a graphite furnace were investigated. The absorbance signals as a function of pre-atomization temperatures were obtained for the analyte, matrix and the analyte in the matrix. In addition, the matrix and the analyte were injected separately on the graphite surface. The comparison of the obtained data with the thermochemical and physical properties of the matrix and the analyte led to conclusions about the interference mechanisms. The type of interference that affects the sensitivity of the analyte depends on the thermal behavior of the matrix before and during the atomization of the element in the graphite furnace. If chlorine atoms are formed by the decomposition of the matrix at temperatures close to the atomization temperature of the element, formation of a metal chloride in the gas phase is responsible from the decrease in the sensitivity. On the other hand, when the matrix is present as a solid or liquid in the graphite furnace while the element atomizes, the occlusion of the element in the matrix occurs. The change of the sensitivity depends on the physical and chemical nature of the analyte and the matrix.