title: Passive sampling of anionic pesticides using the Diffusive Gradients in Thin films technique (DGT).
abstract: DGT passive samplers using Oasis®HLB or Oasis®MAX sorbent were developed for anionic pesticides sampling. They were tested using four model compounds (i.e. bentazon, chlorsulfuron, ioxynil and mecoprop). Polyacrylamide diffusive gel was found to be more suitable than agarose gel for most anionic pesticides sampling. An elution procedure was optimized and diffusion coefficients were determined for quantitative use of the samplers. Depending on the DGT configuration used (HLB or MAX), accuracies better than 30% were demonstrated in laboratory for pH from 3 to 8 and ionic strengths from 10-2to 1 M. Combined with the effective binding capacities of samplers (≥9 μg for each pesticide) and limits of quantification of the method (≤13 ng.L-1using Q-TOF detector) monitoring of numerous aquatic systems can be expected. Except for ioxynil, accurate quantifications were demonstrated in laboratory using a spiked natural water for HLB-DGT whereas MAX-DGT did not give satisfactory results. A further in situ validation was performed in two rivers and showed identical detection frequency between HLB-DGT and POCIS of anionic pesticides (bentazon and mesotrione) whereas calculated concentrations, although within the same order of magnitude, could differ (<70%). HLB-DGT could therefore constitute an interesting alternative to other passive samplers for the monitoring of several anionic pesticides in aquatic systems but more work is required for quantification of molecules from hydroxybenzonitrile chemical group (ioxynil).
authors.affiliation: University of Limoges, Research Group on Water, Soil and Environment (GRESE), 123 Avenue Albert Thomas, 87060, Limoges Cedex, France.
authors.forename: Robin
authors.initials: R
authors.lastname: Guibal
authors.affiliation: University of Limoges, Research Group on Water, Soil and Environment (GRESE), 123 Avenue Albert Thomas, 87060, Limoges Cedex, France. Electronic address: remy.buzier@unilim.fr.
authors.forename: Rémy
authors.initials: R
authors.lastname: Buzier
authors.affiliation: University of Limoges, Research Group on Water, Soil and Environment (GRESE), 123 Avenue Albert Thomas, 87060, Limoges Cedex, France.
authors.forename: Adeline
authors.initials: A
authors.lastname: Charriau
authors.affiliation: University of Limoges, Research Group on Water, Soil and Environment (GRESE), 123 Avenue Albert Thomas, 87060, Limoges Cedex, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Lissalde
authors.affiliation: University of Limoges, Research Group on Water, Soil and Environment (GRESE), 123 Avenue Albert Thomas, 87060, Limoges Cedex, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Guibaud
keywords: Anionic pesticides; Diffusive Gradients in Thin films; Herbicides; Passive sampling; Water analysis