The performance of a new laboratory-constructed cathodic-sputtering atomizer in atomic absorption spectrometry

Abstract

The performance characteristics of a laboratory-constructed cathodic sputtering atomizer for atomic absorption spectrometry have been evaluated. The new atomizer allows for the independent control of argon flow rate and pressure, whereas the only cathodic-sputtering atomizer commercially available for atomic absorption spectrometry (Atomsource, manufactured by Analyte Corporation) does not. Our results follow the model of consecutive, first-order reactions: ▪ where A is the analyte atom that has not yet entered the analysis volume of the atomizer, B is the analyte atom that absorbs and C is the analyte atom that is removed from the analysis volume, and k 1, and k 2 are first order rate constants. The importance of independent control of argon flow rate and pressure is shown by the increase in the k 1 k 2 ratio for Ag for the new atomizer compared to that for the Atomsource. The peak height sensitivity of the new atomizer is up to a factor of 5 better than that of the Atomsource, which does not allow independent control of argon flow rate and pressure. Also, the value of k 2 for the new atomizer has been decreased, the result is a peak area sensitivity for the new atomizer that is 1–2 orders of magnitude better than that of the Atomsource. A parametric evaluation of the new atomizer has shown that most of the improvement in peak area sensitivity results from the increased residence time of the analyte atoms. A comparison of the sensitivity of the new atomizer with the sensitivity of the Atomsource has been made using both peak height and peak area absorbance.