3.2. Analytical performance, validation and application
One of the principal problems related with the determination of
trace elements in organic matrix is the lack of knowledge about the
form of the analyte in the sample. The standard addition techniques
provide the compatibility among the calibration curves
and samples in terms of possible matrix interferences, but also
may provide errors since the forms of element compounds in the
materials to be analysed behave differently to the spiked form
(dos Santos et al., 2007).