  The occurrence of polar pesticides in sediments has not been extensively
investigated because of their relatively poor hydrophobicity and apparently
less persistence in the environment. However, their continuous release into the
aquatic systems calls for the evaluation of their potential accumulation in
sediments and the role of this matrix as a potential source of these compounds.
Considering this, a method based on pressurized liquid extraction (PLE),
extract clean-up by solid phase extraction (SPE) and analyte determination by
liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was
developed and validated to analyze 50 relevant (frequently used and/or
regulated or found in water) medium to highly polar pesticides in sediments.
The method showed good performance regarding accuracy (relative recoveries
between 76% and 124%), precision (relative standard deviation values <20%),
sensitivity (LODs in the low ng/g for most compounds), linearity (coefficients
of determination >0.99), and matrix effects (negligible for all analytes). The
use of an isotope dilution approach for quantification ensures results
reliability. As a part of the validation process, the method was applied to the
analysis of the target pesticides in sediments from the Llobregat River (NE
Spain) showing the presence of five of them, namely, terbutryn, dichlorvos,
terbuthylazine, diazinon, and irgarol. All 5 pesticides, due to both the
concentrations found and their physical-chemical characteristics, demonstrate
high potential for bioaccumulation and risk to the aquatic organisms.
Additional multidisciplinary studies that investigate pesticides occurrence in
the different aquatic compartments and evaluate the potential risks for aquatic
ecosystems are required to assess the environmental impact and significance of
the presence of pesticides in sediments.
