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In this paper, the potential of coupling liquid chromatography with hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF) for the determination of pesticides in a variety of fruit samples (orange peel and flesh, banana skin and flesh, strawberry and pear) has been explored. the quantitative application at residue levels has been proven for two insecticides (buprofezin and hexythiazox), which were satisfactorily determined at three concentration levels, 0.1, 1, and 5 mg/kg, obtaining a suitable linearity range (correlation coefficient > 0.99) of more than 2 orders of magnitude. Satisfactory recoveries have been obtained for both compounds at the three levels tested in all sample matrices, with lowest calibration levels (LCL) of 0.075 and 0.01 mg/kg. The excellent potential of QTOF for identification purposes is illustrated by the high number of identification points (IPs) earned, up to 21, at the highest concentration of 5 mg/kg, or between 11 and 21 at the 0.1 and 1 mg/kg levels. The application of LC-QTOF MS to real samples revealed the presence of several positives at concentrations close to the LCL, all of which were confirmed with more than 11 IPs. The potential of QTOF for elucidation of nontarget analytes has also been demonstrated by the finding of one transformation product (TP) of buprofezin in a banana skin sample. This TP was identified by obtaining the full scan product ion spectra at different collision energies with acceptable accurate mass deviation. The work performed in this paper illustrates the suitability and excellent confirmatory potential of LC-QTOF MS for pesticides residues analysis in food samples.

A series of analyses were performed for 64 days by using gas chromatography with mass spectrometric detection to evaluate the effect of washing on the presence of 5 pesticide residues in the olive fruits. As olives are not stored in olive mill but processed on the same day of the harvest it could be concluded that herbicides present in the olives by contamination due to short contact with the soil when they are harvested could be effectively eliminated by washing.

This study demonstrates a method of stabilizing specifically recombinant antibody fragments in nonpolar and polar solvents.

This article examines pesticide concentrations in the air, rain, and surface water of an estuary of Chesapeake Bay.

Model evaluations are commonly undertaken using relatively sparce data, and the criteria for such evaluations are often not fully addressed. For instance, less effort has been made to evaluate models based on their prediction capability. In this study we compared several chemically and physically based nonequilibrium models for their predictions of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) transport in a uniformly packed Sharkey soil (Vertic Haplaquept). The models compared were a nonlinear multireaction model (MRM), a second-order model (SOM), and their coupled versions with a mobile-immobile model (MIM), MRM-MIM and SOM-MIM. Model parameters were derived from kinetic batch experiments and were used to predict atrazine column breakthrough curves (BTCs) for different pore water velocities (0.52-2.17 cm [h.sup.-1]), aggregate sizes (0-2, 2-4, and 4-6 mm), flow interruptions (0, 4, and 16 d), and soil column lengths (10 and 15 cm). For each model, nine formulations reflecting various adsorption sites were evaluated. Based on root mean squared errors and sums of squared errors, considerable improvement in atrazine BTC predictions was achieved using SOM compared with MRM. Furthermore, SOM was more sensitive to different model formulations than MRM. Coupled MRM-MIM did not improve atrazine BTC prediction. Although goodness of mode] predictions varied with individual columns, we concluded that SOM-MIM with four parameters and a time-dependent mass transfer coefficient ([Alpha]) best described atrazine retention and transport in Sharkey soil.

Metabolites are commonly found more frequently in groundwater than their parent compounds. This was gleaned from an examination of the occurrence and distribution of selected pesticides and their metabolites from 837 water-quality samples from 303 wells throughout the Midwest, where five of the six most frequently detected compounds were pesticide metabolites. Alachlor ethanesulfonic acid was detected nearly 10 times as often and at more significant concentrations than its parent compound alachlor. Results indicate that the quantification of pesticide metabolites is necessary to accurately estimate the effects of chemical use on groundwater.

A systematic exposure assessment procedure was developed to assess the exposure of humans to chemicals in drinking water. The procedure was used to assess the exposure to atrazine, a widely used pesticide in the Corn Belt, of populations in Ohio, Illinois and Iowa. The results show that less than 0.25% of the assessed populations are exposed to atrazine above the lifetime health advisory level of 3.0 parts per billion (ppb), and that 94%-99% of assessed populations are exposed to atrazine levels of less than 1.0 ppb. It was concluded that atrazine is not a significant health threat based on the current knowledge of atrazine toxicity.

Supercritical fluid extraction (SFE) was used to recover s-triazines and phenylurea herbicides from spiked sediments to determine the effects of extraction temperature, time of extraction and supercritical fluid density on analyte recovery. Results showed that the use of unmodified supercritical carbon dioxide caused low and variable analyte recovery, but this can be improved with acetone modification. SFE was much faster than Soxhlet extraction, improved analyte recovery and reduced solvent and labor requirements.

In the global market for fresh fruit, the United States is a major exporter of apples and orange fruits to various countries. However, exporters need to be mindful of the [...]

Innovations in pesticide residue analysis are increasing with the development of more sophisticated instruments in liquid chromatography and gas chromatography. Details on these advancements are discussed.

This study illustrates the successful combination of fast GC and tandem mass spectrometry to determine 360 pesticides spiked in a QuEChERS apple extract. To handle the high number of monitored [...]

The EPA has agreed to implement the recommendations made by the National Academy of Sciences in its report entitled,'Pesticides in the Diets of Infants and Children.' The report urges the use of immature animals aside from mature ones as test subjects for pesticides being developed. In addition, it called on pesticide companies to conduct yearly food consumption surveys of children beginning from the age of five-years old. Also, the report called for increased pesticide residue sampling of food and non-food sources., EPA Administrator Carol Browner has announced actions that the Agency will take to carry out recommendations of the National Academy of Sciences report Pesticides in the Diets of Infants and [...]