Multielement analysis of geological and related non-conducting materials using spark ablation and a sequential spectrometer

Abstract

Spark ablation (SA) coupled to a sequential inductively coupled plasma atomic emission spectrometer (ICP-AES) is evaluated for multielement analysis of geological and related non-conducting materials. Long-term stability conditions were established which allowed the determination of major, minor, and trace elements (Si, Ca, Ti, Al, Mg, Fe, Mn, Sr, Ba, Zr, Cr, V and Zn). The influence of the observation height was determined and the role of water vapor in the plasma evaluated. In the latter case the presence of water vapor resulted in a reduction of intensity and magnification of interference effects. The intensity and RSDs increased and improved, respectively, with decreasing particle size from about 3% to 1%. In the case of fine grained sediments, intensities for the involatile elements were relatively higher, possibly due to more efficient atomization and ablation rates. Scanning electron micrographs indicate that while melting still played a role in the ablation process, materials were also removed by mechanical ablation. The accuracy was determined using a wide range of geological standard reference materials. The use of Si I 251.611 nm as the internal standard resulted in a significant improvement in accuracy and compensation of particle size effects. Without Si as the internal standard the mean correlation coefficient was 0.62 ± 0.37; with Si the mean coefficient was 0.97 ± 0.36.