Use of sol-gels as solid matrixes for trace analysis by UV laser ablation and laser-enhanced ionization detection

Zirconium and silicon sol-gels were investigated as solid materials for trace elemental analysis of pelletized solid samples by laser ablation and laser-enhanced ionization. The highly homogeneous dispersion of an internal standard spiked in the solid material obtained with the sol-gel formation process leads to a significant improvement in signal repeatability and to an increase in the precision of measurements through better correction of variations in the laser ablation rate. Signal repeatability values of 5-8% RSD were obtained for Pb in NIST 1632c Bituminous Coal sample pellets prepared using both sol-gels, as compared to 9-21% for graphite-based sample pellets. Furthermore, the zirconium sol-gel was shown to offer better resilience to signal bias due to preferential ablation and a more accurate correction of ablation rate using the internal standardization method.