tesis doctoral montti - RiuNet - Universidad Politécnica de Valencia

analytes that are easily removed from aqueous solutions, solid
phase microextraction is the best choice, with high injected mass
and consequently leading to better chromatographic response than
those observed in other methods. The use of the programmed
temperature vaporization injector is more appropriate than
traditional injection techniques when an organic solvent extraction
is needed. The implementation and optimization of solid phase
microextraction and large sample volume injection by multiple
injections on solvent vent mode, in the programmed temperature
vaporization injector, have allowed the determination and
identification of triadimefon, penconazole, propiconazole and
tebuconazole residues in fresh blueberries and blueberry juices
spiked and in real samples by gas chromatography and mass
spectrometry with adequate precision and high recovery and
sensitivity. The limits of detection and quantification of these
techniques are about two orders lower than the maximum residue
guideline limits for these analytes and are comparable to those
observed in published literature. On the other hand, when a
sample contains very low residue levels, the sensitivity of the
method could be significantly increased by extending the fiber
immersion time. The implementation and optimization of the
extraction process, using polidimetilsiloxan as polymers coating,
and changes in the chromatographic conditions allowed
determination of other pesticides commonly used for crops in the
region. Residues of malathion, chlorpyrifos, tebuconazole,
trifloxystrobin, chlorothalonil, fludioxonil and boscalid were
detected and quantified in real samples. Spiked samples were
used in all cases for calibration because of the matrix effect.