Extension of the standardless method of analysis in electrothermal atomic absorption spectroscopy to elements of medium volatility :experimental results for Co,Cr,Cu,Fe,Mn and Ni

摘要

In previous papers it has been demonstrated that by using a special atomiser and power supply it was possible with elements of high volatility like Hg,Cd,Pb and Ag to obtain absorbance vs.time curves of a form consistent with the assumption that all atoms presnet in a condensed state at the beginning of the atomisation step are simultaneously present in the vapour phase inside the atomiser.In fact,these absorbance vs.time curves closely fit a model,which assumes a very rapid atomisation and homogenisation of the atoms at the centre of the atomiser followed by diffusion out of he graphite tube.The absorbance in these curves is,theoretically,anasymptotic maximum,which is related,if the experimental conditions are wel chosen ,to the total number of atoms injected,through the Lambert-Beer law.In this case the absorbance data can be used,if the proportionality constant is known,for standardless analysis.The increase of the atomisation temperature,as a consequence of a new design of the atomisation system,has ade it possible to extend the method to elements of medium volatility like Co,Cr,Cu,Fe,Mn and Ni.The elements cited are those so far analysed but it is easy to predict that the method can be applied to the majority ofhe eleemnts,thus greatly increasing its usefulness in a large number of real samples.