Analysis of soil and sediment samples by laser ablation inductively coupled plasma mass spectrometry

The analysis of soil and sediment samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was studied. Solution-based ca libration was used for the quantification of trace elements in these sample s. In most cases, the measured concentrations were within +/- 20% of the ce rtified values using Ni-60 or Ag-107 as the internal standard. Measurements with Ag were carried out to investigate whether an internal standard could be spiked into soils for quantification purposes. The influence of particl e size on the applicability of sample spiking was briefly studied, and it w as demonstrated that particle size could significantly influence measuremen ts if only the surface constituents of the particle were ablated. Use of Ca -43 or Ca-44 as an internal standard produced poorer results owing to inter ferences at these masses. In some cases, such as with Sr, Ba, Y and Rb, the measured concentrations were low by a factor of 2-3. This could be remedie d by using one of these elements as an internal standard for the others. Th e effects of elemental speciation, organic content and particle size were i nvestigated. Elemental speciation and organic content of the soils did not appear to significantly affect the LA-ICP-MS measurements. Particle size, h owever, was found to influence the precision and sensitivity of the measure ments. Samples with smaller particle sizes yielded higher signal levels and better precision.