The system was further tested by sampling a test aerosol of NIST Standard Reference Material 1648, Urban Particulate Matter. Up to 12 elements were analyzed in three separate batches by simultaneous multi-element atomic absorption spectroscopy. Elements were grouped according to similar analytical conditions and expected concentrations. Details of the experimental setup and analysis of samples will be presented. The determination of some elements, however, is complicated by spectral interferences which occur when the nominal mass of two species is the same.
Spectral interferences are particularly troublesome for determinations at trace levels.
Although mathematical corrections using the isotope ratios of the elements are available, it is difficult to correct for the contribution from polyatomics. For some elements, adjusting the operating conditions of the plasma and reducing the plasma potential is necessary to reduce interfering background ions. The cool plasma is attained by reducing the rf power, increasing the nebulizer gas flow rate, and increasing the sampling depth of the plasma. All elements except K have usable less abundant isotopes, but sufficiently low detection limits cannot be obtained under normal plasma conditions. The semiconductor industry is particularly interested in this method for evaluating reagent purity.