Simple analytical methodology based on solid phase extraction for monitoring pesticide residues in natural waters.

Pesticide contamination of natural waters due to agricultural activities has been a widely publicized topic over the past 30 years and will continue to be a problem in the future. The determination of pesticide residues in water samples is necessary for solving various environmental problems. The aim of this work was to develop an efficient method on the basis of solid phase extraction (SPE) technique for the determination of 34 multiclass pesticides in natural waters. SPE using C18 extraction disks followed by gas chromatography (GC-MS) and liquid chromatography (LC-MS) were used for the determination of various pesticides residues in environmental waters. The developed SPE method provided good repeatability and reproducibility range, high extraction efficiency and low LODs. The performance results confirm the usefulness of the proposed methodology for the analysis multiclass pesticides in natural waters. The key benefits of this methodology are:•It possesses the advantages of SPE (fast, simple, highly sensitive) and could be potentially extended to other classes of pesticides.•It can be used as a useful tool for monitoring purposes on natural waters.•The validated methodology meets regulatory requirements established by the EU [1] and other authorities of developed countries [2].

Environmental monitoring and risk assessment of pesticide residues in surface waters of the Louros River (N.W. Greece).

Estuarine environments are being constantly stressed by new sources of pollution (e.g. pesticides) derived from activities of industry and intensive agriculture. The present study aims at quantify pesticides of three different categories (fungicides, herbicides and insecticides) in the Louros River (Epirus region, North-Western Greece). A monitoring study of 34 compounds was carried out in surface river waters from June 2011 until May 2012. Seven water sampling stations were established and 35 water samples were collected. A solid-phase extraction (SPE) method coupled with gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS), depending on the compound, was developed and validated. During the monitoring study 25 pesticides were detected (13 herbicides, 9 insecticides, 3 fungicides). The most commonly encountered pesticides were quizalofop-ethyl, trifluralin and pendimethaline. Tebufenpyrad was found in all sampling stations and seasons, with the highest concentrations of 0.330 µg/L at Tsopeli Lagoon exceeding the rather low concentrations reported nationwide. Regarding the environmental risk due to the presence of target compounds in surface waters, this was estimated by calculating risk quotients (RQs) for different aquatic organisms (algae, zooplankton and fish). The results denoted a possible threat for the aquatic environment, rendering in this way the RQ method as a useful screening tool. In any case, further extensive study is needed for acetochlor, pirimiphos-methyl, endosulfan-a and azinphos-ethyl in order to better correlate their occurrence and potential toxic effects in aquatic life and humans.