Pesticides are an important group of agrochemicals used for food crop protection. Unfortunately, these compounds are easily accumulable in soils becoming a real environmental pollution risk and can contaminate surface water directly as spray drift or run-off, and also via drainage through the soils of treated farmland [1, 2]. For these reasons, there is increasing need for the development of well validated, accurate, time-saving, low cost, modern, multicomponents methods. In the light of the aforementioned, the aim of this study was to validate a sensitive multi-residue method for the target analysis of sixteen pesticides in soils and waters.The selected pesticides were: alachlor, atrazine, buprofezin, chlorfenvinphos, chlorpyriphos, diazinon, diuron, fenitrothion, fenthion, hexythiazox, imazalil, isoproturon, malathion, prochloraz, tolclophos-methyl and trifluralin. Pesticides from soil were extracted by pressurized liquid extraction (PLE), using an ASE 200 system from Dionex. Soil samples (10 g) were introduced into 11 mL cell and heated to 100 ºC for 7 min and extracted by ethyl acetate with a flush volume of 100 % in one cycle. Water was extracted by solid-phase extraction (SPE). Water samples (500 mL) were acidified and then extracted using Oasis HLB cartridges previously conditioned with methanol and water. Analytes were eluted with 4 mL. The residue analyses were performed by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS) multi-residue method. Separation was made with a Luna 3μm C18 (Phenomenex®) analytical column. The mobile phase was MeOH and H2O 5 mM ammonium formate gradient composition, used in conjunction with positive mode electrospray ionization tandem mass spectrometry. Performance characteristics of the proposed method were established. Selectivity, linearity, precision, recoveries and limits of detection (LODs) and quantification (LOQs) were studied. The method allowed LOQ from 0.03 μg/kg to 0.05 μg/kg. Recoveries ranged from 75 to 95% with relative standard desviation < 18%. The results of the validation procedure confirmed that the method is suitable for the planned purpose. This method has been applied successfully to the analysis of incurred water and soil samples from Natural Park of L ́ Albufera. The results revealed the presence of some pesticides at several concentration levels both in the soil and water samples. Nevertheless, they exist in a range of residual levels

This work has been supported by the Spanish Ministry of Science and Innovation through the project Consolider-Ingenio 2010 CSD2009-00065, as well as by this Ministry and the European Regional Development Funds (ERDF) (project GCL2007-66687-C02 01/BOS).

Ponencia presentada en el 28th International Symposium on Chromatography celebrado en Valencia del 12 al 16 de septiembre de 2010

Peer Reviewed