4. Conclusions
It has been shown that pellets produced from spiked keratin
powder do not make suitable standards for analysis of fingernails
by LIBS. We suggest that this is because of the supramolecular
structure (fibers, supercoils, etc.) of keratin in fingernails. It has
also been shown that standards made by depositing aqueous
solutions onto filter paper give plasma temperatures, electron
densities, and ablation properties that are similar to those
observed on nails. Thus, these filter paper standards are more
appropriate for use in calibrating the LIBS experiment for analysis