Occurrence and Distribution of Carbamate Pesticides and Metalaxyl in Southern Ontario Surface Waters 2007-2010.

Surface water sampling in 2007-2010 measured the occurrence of carbamates and metalaxyl during base flow conditions and wet weather events in southern Ontario surface waters. Carbaryl, metalaxyl and pirimicarb were the most frequently detected compounds. In 2008 these three compounds were detected in over 50 % of the samples. Overall mean concentrations of carbaryl and metalaxyl over the course of the study (2007-2010) were 15 and 18 ng/L, respectively. Elevated concentrations of carbaryl (~100 to ~950 ng/L) appeared associated with wet weather (high flow) events, while highest concentrations of metalaxyl (~20-1330 ng/L) were correlated with base flow conditions. We attributed these observations as the result of runoff of carbaryl from the watershed during rain events, while metalaxyl contamination may have resulted primarily from spray drift.

Sorption of 14C-carbofuran in Austrian soils: evaluation of fate and transport of carbofuran in temperate regions.

Carbofuran is an anticholinesterase carbamate commonly used as an insecticide, nematicide and acaricide in agricultural practice throughout the world. However, data on its sorption in temperate soils from Europe is limited. Laboratory studies were conducted to determine the adsorption of carbofuran on three distinct Austrian soils using batch experiments and radiometric techniques. Carbofuran adsorption capacity of the soils was found to be low in the three soils tested and showed to be related to the soils clay and organic carbon contents. The pesticide presented linear adsorption isotherms in all of the three soils. Due to the low sorption of carbofuran in the soils tested and to its high water solubility, there is a risk of migration to water bodies through run off and consequent negative effects on aquatic organisms and soil biota.

Factorial design optimization of experimental variables in preconcentration of carbamates pesticides in water samples using solid phase extraction and liquid chromatography-electrospray-mass spectrometry determination.

An experimental design was applied for the optimization of extraction process of carbamates pesticides from surface water samples. Solid phase extraction (SPE) of carbamates compounds and their determination by liquid chromatography coupled to electrospray mass spectrometry detector were considered. A two level full factorial design 2(k) was used for selecting the variables which affected the extraction procedure. Eluent and sample volumes were statistically the most significant parameters. These significant variables were optimized using Doehlert matrix. The developed SPE method included 200mg of C-18 sorbent, 143.5 mL of water sample and 5.5 mL of acetonitrile in the elution step. For validation of the technique, accuracy, precision, detection and quantification limits, linearity, sensibility and selectivity were evaluated. Extraction recovery percentages of all the carbamates were above 90% with relative standard deviations (R.S.D.) in the range of 3-11%. The extraction method was selective and the detection and quantification limits were between 0.1 and 0.5 µg L(-1), and 1 and 3 µg L(-1), respectively.