Theoretical evaluation of solid sampling electrothermal atomic absorption spectrometry for screening purposes

Obtaining results in the determination of metals by electrothermal atomic absorption spectrometry is conditioned by the non-homogeneity of the sample and the possible appearance of outliers, which make it difficult to obtain reliable results with only a few measurements. In order to establish the optimum conditions for using the technique as a screening method, 18 000 results corresponding to different possible situations were simulated by computer and subsequently analysed using information theory. In view of the results obtained, it can generally be claimed that the median can be used to better effect than the mean value as the former is less affected by the potential presence of outliers. Using the median and with normal working conditions, the minimum number of measurements that need to be carried out to guarantee a recall of over 0.95 in a screening method ranges from 5 to 20, involving between 15 min and I h work.