Comparison of the lead 168-nm and 220-nm analytical lines in high iron and aluminium matrices by inductively coupled plasma-optical emission spectrometry

Virtually all photomultiplier-based inductively coupled plasma spectrometers (ICPS) use the lead (Pb) 220.3-nm analytical line, even though it has severe background continuum and interelement interference from the aluminium (Al) 220.4-nm line, and background shift due iron (Fe). Many Pb analytical lines above 220 nm are unsuitable due to poor detection limits. There are no reports in the literature on the use of Pb analytical lines below 220 nm, especially the 168.2-nm line recommended by Spectro Analytical (Kleve, Germany). The Pb 168-nm analytical line has a superior detection limit and is less prone to matrix, background continuum radiation and inter-element interference from high concentrations of Al and Fe compared to the Pb 220-nm analytical line. This has been demonstrated by the better precision and accuracy of analysis of soils containing high levels of Al and Fe.