Application of palladium as a chemical modifier in electrothermal atomic absorption spectrometry with a tungsten tube atomizer

Abstract

The characteristic mass, expressed as integrated absorbance, determined for a number of volatile elements in a tungsten tube atomizer (WETA) is higher by a factor of 3–10 compared with a graphite furnace (GF). The use of palladium as a chemical modifier increases the sensitivity for most of the elements of interest, except for silver, by 20–200% in the WETA. This effect has not been encountered in the GF. The temperatures to which the elements could be stabilized by palladium are comparable to those in the GF and are typically between 850 and 1300 °C. Up to 15% hydrogen in the argon purge gas had no influence on the sensitivity but increased the lifetime of the tungsten tubes. Higher concentrations of hydrogen in the purge gas resulted in a decrease in sensitivity for most of the elements investigated. Interference of HClO₄ in the WETA was found to be less pronounced than has been reported for the GF. Most of the interferences due to sodium chloride, calcium chloride, hydrochloric acid and perchloric acid are significantly reduced by the addition of palladium as a chemical modifier.