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United States Department of Agriculture

Agricultural Research Service

Title: Determination of Metolachlor Volatile Flux from Soil Using Solid Phase Microextraction

Authors
item McConnell, Laura
item Kim, Hyunook
item Nochetto, Cristina
item Gish, Timothy
item Prueger, John

Submitted to: American Chemical Society National Meeting
Publication Type: Proceedings
Publication Acceptance Date: March 15, 2001
Publication Date: N/A

Interpretive Summary: When pesticides are applied to agricultural fields, some pesticide material is lost to the atmosphere either during or after the application. The pesticide material can be transported in the air to places where it may have toxic effects on wildlife or humans. In order to design farming techniques that minimize losses to the atmosphere, scientific experiments are required that accurately measure this effect. The traditional methods for measuring pesticide concentrations in air are very labor intensive. This project describes a new method, solid phase microextraction (SPME), that uses a small, passive air sampler that can be analyzed quickly in the field. A comparison of the SPME method with a traditional air sampler method showed consistently higher concentrations from SPME. However, these results are encouraging and have the potential to save scientists time and money, and allow them to carry out more detailed experiments. Information developed from these experiments will aid in the development of new farmin techniques that will protect air quality.

Technical Abstract: Volatile emissions from soil are an important release pathway to non-target areas for many semi-volatile and volatile pesticides. Pesticide residues released to the atmosphere during and after application can be transported long distances and re-deposited to ecologically sensitive areas. Therefore it is important to carry out valid field-scale experiments to accurately characterize the effects of different soil types, meteorologica conditions, and agricultural practices on the volatile release of pesticides. This project was designed to test the utility of solid phase microextraction (SPME) as a passive air sample collection method in the measurement of pesticide emissions from soil and to compare the results with the traditional polyurethane foam (PUF) sorbent method. The goal of this approach is to reduce the amount of time required to obtain air concentration results during volatile flux experiments using near real-time econcentration measurements and to increase the resolution of sample collection. Calibration of the fiber coating was carried out using a gas standard generator. In preliminary results, air concentrations measured with the SPME were a factor of 3-5 higher than with PUF. This suggests either a problem with the calibration method or enhance adsorption of metolachlor by the SPME fiber coating due to environmental conditions. These results are encouraging, however, and this methodology has the potential to greatly increase the efficiency and accuracy of volatile flux measurement experiments, providing scientists with important information of pesticide release to the atmosphere.

Last Modified: 7/31/2014
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