Validation and expanded uncertainty determination of pesticides in water; and their survey on paddy rice irrigation water from Argentina.

A solid-phase microextraction (SPME) coupled to gas chromatography-mass spectrometry method was validated for the simultaneous determination of penconazole, cyproconazole, epoxiconazole, deltamethrin, azoxystrobin and kresoxim-methyl in paddy rice irrigation water. Different SPME fiber coatings and pH values were tested. Polydimethylsiloxane (PDMS) and pH 7 were chosen to optimize extraction. All pesticides presented a recovery percentage between 90.5 and 104.2%; and detection and quantification limits were 0.03 and 0.05 µg/kg for azoxystrobin and cyproconazole, 0.02 and 0.05 µg/kg for deltametrhin and epoxiconazole, 0.02 and 0.03 µg/kg for kresoxim-methyl, and 0.01 and 0.02 µg/kg for penconazole. The expanded uncertainty was estimated for all pesticides showing results lower than 20%. A total of 100 paddy rice irrigation water samples, collected in different rice fields from Argentina, were evaluated. The study showed that 86 of them presented residues. The concentrations exceeded the values that were set by European legislation and the frequencies were higher than 86% so the agricultural practices should be revised.

Pesticide survey in water and suspended solids from the Uruguay River Basin, Argentina.

The Uruguay River is receptor of pollutants, such as pesticides, from agriculture activities along its course. The present study reports concentration levels of organochlorinate, organophosphorus, and other pesticides in water and suspended solids in nine sampling sites of the Uruguay River. Data analyses included principal component analysis (PCA) to assess differences between sampling sites contamination. Most of the tested pesticides were ubiquitous due to the widely use in the chemical control of pests implemented in the region. Detected concentrations of aldrin, chlordane, dieldrin, endrin, heptachlor epoxide, lindane, 4,4'-DDT, endosulfan, chlorpyrifos, diazinon, methyl-parathion, and malathion were found to be over regional and international concentration level guidelines, according to the European Union, the US Environmental Protection Agency, or the Argentinean Secretariat of Environment and Sustainable Development. For this reason, future studies in Uruguay River Basin are needed.

Development and validation of an SPME-GC method for a degradation kinetics study of propiconazole I, propiconazole II and tebuconazole in blueberries in Concordia, the main production area of Argentina.

An analytical method for the simultaneous determination of propiconazole isomers and tebuconazole residues in blueberries was developed using solid-phase microextraction (SPME) coupled to gas chromatography. Confirmation was performed by gas chromatography-mass spectrometry in selected-ion monitoring mode. The SPME fibre coating selected was CWX-DVB, and the pH was adjusted to 7 with NaOH. The method is selective with adequate precision and high accuracy and sensitivity. Recoveries ranged between 97.4% and 98.9% for all compounds; and detection and quantification limits were respectively 0.21 and 0.49 µg kg-1 for propiconazole I; 0.16 and 0.22 µg kg-1 for propiconazole II; and 0.16 and 0.48 µg kg-1 for tebuconazole. The degradation of these fungicides in blueberries followed first-order rate kinetics. The half-life times for flowering and fruit set applications were respectively 4.0 and 10.3 days for propiconazole I, 4.0 and 11.4 days for propiconazole II, and 3.5 and 12.4 days for tebuconazole.

Mycotoxigenic potential of fungi isolated from freshly harvested Argentinean blueberries.

Alternaria alternata, A. tenuissima, Fusarium graminearum, F. semitectum, F. verticillioides, Aspergillus flavus, and Aspergillus section Nigri strains obtained from blueberries during the 2009 and 2010 harvest season from Entre Ríos, Argentina were analyzed to determine their mycotoxigenic potential. Taxonomy status at the specific level was determined both on morphological and molecular grounds. Alternariol (AOH), alternariol monomethyl ether (AME), aflatoxins (AFs), zearalenone (ZEA), fumonisins (FBs), and ochratoxin A (OTA) were analyzed by HPLC and the trichotecenes deoxynivalenol (DON), nivalenol (NIV), HT-2 toxin (HT-2), T-2 toxin (T-2), fusarenone X (FUS-X), 3-acetyl-deoxynivalenol (3-AcDON), and 15-acetyl-deoxynivalenol (15-AcDON) by GC. Twenty-five out of forty two strains were able to produce some of the mycotoxins analyzed. Fifteen strains of Aspergillus section Nigri were capable of producing Fumonisin B1 (FB1); two of them also produced Fumonisin B2 (FB2) and one Fumonisin B3 (FB3). One of the F. graminearum isolated produced ZEA, HT-2, and T-2 and the other one was capable of producing ZEA and DON. Two A. alternata isolates produced AOH and AME. Four A. tenuissima were capable of producing AOH and three of them produced AME as well. One Aspergillu flavus strain produced aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), and aflatoxin G1 (AFG1). To our knowledge, this is the first report showing mycotoxigenic capacity of fungal species isolated from blueberries that include other fungi than Alternaria spp.

Method development and validation for cyprodinil and fludioxonil in blueberries by solid-phase microextraction gas chromatography, and their degradation kinetics.

A method of analysis for residues of cyprodinil and fludioxonil in blueberries was developed. Fungicide residues were determined by solid-phase microextraction coupled to GC with nitrogen-phosphorous detection. The effect of pH values and fibre coatings was studied. The solid-phase microextraction fibre coating selected was 100 µm polydimethylsiloxane. The method was selective, with adequate precision and high accuracy and sensitivity. Apparent recoveries ranged within the 99-101% range for cyprodinil and the 98-100% range for fludioxonil; LODs and LOQs were 1.2 and 3.9 µg/kg for cyprodinil and 0.4 and 1.3 µg/kg for fludioxonil, respectively. Statistical parameters indicated a matrix effect; consequently, calibration was performed on spiked samples. Degradation of cyprodinil and fludioxonil was studied in a blueberry field located in Concordia (Argentina), with fruit from Emerald and Jewel varieties. The degradation of these fungicides in both blueberry varieties studied followed first-order rate kinetics for both fungicides, and the half-life for cyprodinil was 2.2 and 3.4 days for Emerald and Jewel cultivars, respectively, and for fludioxonil was 12.7 and 16.3 days, respectively.

Method development and validation for boscalid in blueberries by solid-phase microextraction gas chromatography, and their degradation kinetics.

Analytical method for the residues of boscalid in blueberries was developed. Fungicide residues were determined by solid-phase microextraction (SPME) coupled to gas chromatography with micro-electron capture (µ-ECD) detector. The effect of pH values and fiber coatings were studied. The SPME fiber coating selected was 100 µm PDMS. The method is selective with adequate precision and high accuracy and sensitivity. Recoveries ranged within the 98-104% range, and detection and quantification limits were 1.33 and 4.42 µg/kg, respectively. Statistical parameters indicated the occurrence of matrix effect; consequently calibration was performed on spiked samples. Degradation of boscalid was studied in a blueberry field located in Concordia, Argentina, with fruits from Emerald and Jewel varieties. The degradation of boscalid in both blueberry varieties studied followed a first order rate kinetics and the half-life for boscalid was 5.3 and 6.3 days for Emerald and Jewel cultivars, respectively.