However, performing a quantitative

However, performing a quantitative analysis is no simple matter,
as the element emission lines in the LIBS spectrum are closely
related with the matrix in which they are embedded. The matrix
effects occur in the LIBS spectra for several reasons, however the
major cause of them is the change of temperature and electron
density of the plasmas induced on different matrix targets. This
is due to variations in both the ablation and laser plasma interaction
processes, resulting also in possible variations of plume
expansion in the background gas. As a result, different excitation
and ionization levels of plasma species are achieved (Anzano, Villoria,
Ruíz-Medina, & Lasheras, 2006; Krasniker, Bulatov, & Schechter,
2001). This signal feature makes it difficult to find the
appropriate calibration standards for the LIBS methods. In some
cases the appearance of the so-called matrix effects can be reduced
by using a multivariate calibration, internal standard or calibration
free method (Ciucci et al., 1999; Doucet, Belliveau, Fortier, & Hubert,
2007; Mohamed, 2008; Vrenegor, Noll, & Sturm, 2005), however
significant efforts have been made to adapt conventional
calibration to LIBS methods.
In this paper, a new proposal for Ca quantitative determination
in breakfast cereal samples using LIBS was evaluated. Conventional
calibration using commercial cereals as standards was experimented
in order to minimize the matrix effects. The limit of detection
(LOD) of the LIBS method was estimated to assess its
application in quality control laboratories.