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.