azoxystrobin and diflufenican

Pesticides residues in aquatic ecosystems are an environmental concern which requires efficient analytical methods. In this study, we proposed a generic method for the quantification of 13 pesticides (azoxystrobin, clomazone, diflufenican, dimethachlor, carbendazim, iprodion, isoproturon, mesosulfuron-methyl, metazachlor, napropamid, quizalofop and thifensulfuron-methyl) in three environmental matrices. Pesticides from water were extracted using a solid phase extraction system and a single solid-liquid extraction method was optimized for sediment and fish muscle, followed by a unique analysis by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Limits of quantification were below 5 ng L(-1) for water (except for fluroxypyr and iprodion) and ranged between 0.1 ng g(-1) and 57.7 ng g(-1) for sediments and regarding fish, were below 1 ng g(-1) for 8 molecules and were determined between 5 and 49 ng g(-1) for the 5 other compounds. This method was finally used as a new routine practice for environmental research.

Topics: Acetamides; Aminoimidazole Carboxamide; Animals; Benzimidazoles; Carbamates; Chemical Fractionation; Chromatography, Liquid; Environmental Monitoring; Fishes; Geologic Sediments; Hydantoins; Isoxazoles; Methacrylates; Muscles; Naphthalenes; Niacinamide; Oxazolidinones; Pesticide Residues; Pesticides; Phenylurea Compounds; Propionates; Pyrimidines; Quinoxalines; Reproducibility of Results; Solid Phase Extraction; Strobilurins; Sulfonylurea Compounds; Tandem Mass Spectrometry; Thiophenes; Water Pollutants, Chemical

The extent of within field variability in the degradation rate of the pesticides isoproturon, azoxystrobin and diflufenican, and the role of intrinsic soil factors and technical errors in contributing to the variability, was investigated in sites on sandy-loam and clay-loam. At each site, 40 topsoil samples were taken from a 160 x 60 m area, and pesticides applied in the laboratory. Time to 25% dissipation (DT25) ranged between 13 and 61 weeks for diflufenican, 5.6 and 17.2 weeks for azoxystrobin, and 0.3 and 12.5 weeks for isoproturon. Variability in DT25 was higher in the sandy-loam in which there was also greatest variability in soil chemical and microbial properties. Technical error associated with pesticide extraction, analysis and lack of model fit during derivation of DT25 accounted for between 5.3 and 25.8% of the variability for isoproturon and azoxystrobin, but could account for almost all the variability for diflufenican. Azoxystrobin DT25, sorption and pH were significantly correlated.

Topics: Animals; Biodegradation, Environmental; England; Environmental Monitoring; Hydrogen-Ion Concentration; Methacrylates; Niacinamide; Pesticides; Phenylurea Compounds; Pyrimidines; Soil; Soil Microbiology; Soil Pollutants; Strobilurins; Time Factors; Water Movements