Permanent modifiers for electrothermal atomization atomic absorption spectometry

Abstract

The technique of electrothermal atomization atomic absorption spectrometry (ETA-AAS) is widely used for the analysis of samples originating from many sources, such as from the industry and from the environment. Many of these analyses which are performed, are vital for the operation, quality control and monitoring of the products produced in the industry, as well as the byproducts and effluents produced by these processes. Unfortunately, many of these analyses are prone to interferences, which lead to troublesome, inaccurate and costly analyses. Traditionally, chemical modifiers were used to overcome these interferences, but owing to certain limitations of these modifiers, a need arose for a new type of modifier. The envisaged modifier must be able to improve the quality of analyses by improving the sensitivity, detection limits and versatility of the conventional chemical modifiers. This investigation involves the use of a low pressure argon glow discharge. The discharge will sputter a solid metal chemical modifier, such as iridium or rhodium, onto the inside of a graphite tube to produce a permanent modifier. To begin with, the operational characteristics and optimization of the sputtering process for each of the modifiers were investigated. Secondly, the ashing curves and other analytical performance characteristics were determined for Pb and As in three matrices, namely sulphate, nitrate and chloride using the permanent modifiers. The analytical characteristics of the permanent modifiers were compared to the performances of the conventional chemical modifiers and comparisons and conclusions were drawn as to the performance and effectiveness of the permanent modifiers.