Online electrothermal heating of laser-generated aerosols: effects on aerosol particle size and signal intensities in ICPMS

To achieve separation of isobaric interferences and minimization of matrix related interferences for laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) electrothermal heating of laser generated aerosols was investigated by analyzing a range of solid samples: NIST SRM 610, MBH B26, BAM M381, BAM M601 and Tantalum. ICPMS measurements showed that individual elements can be removed from the laser-generated aerosol at characteristic temperatures for different solid materials. Signal reduction as high as 3 orders of magnitude were achieved for volatile elements, such as Ag and Cd when heating laser-generated aerosol of NIST SRM 610 silicate glass. A signal reduction of more than 99% was obtained for Rb while Sr remained practically unaffected. A temperature- and matrix-dependent change of particle size distribution after aerosol heating was observed by means of laser light scattering (direct aerosol visualization) and scanning electron microscopy. In the temperature range between 900 and 1,200 °C, element unspecific signal suppression was observed, which could be related to a change of the particle size distributions.