S1011: Water Quality Methodology for Crop Protection Chemicals (S271)
Statement of Issues and Justification
Isolation of crop management chemicals from water presents many different problems. Large volumes of water must be extracted to obtain the sensitivity necessary for governmental regulations. Often large volumes of water have to be refrigerated and transported to analytical laboratories. Depending on the methods of shipment this can be expensive as well as difficult to obtain without interferences and breakage. Possible chemical degradation of the sample prior to analysis and the EPA suggestion that analysis be accomplished within 24 hours can also impose complications.In addition to these technical difficulties, the analysis of some crop management chemicals in the past has typically consumed large volumes of solvents, which then become large volumes of hazardous wastes that laboratories must dispose of properly. The need for the analysis of crop management chemicals is not likely to end in the near future even though the amount of organically grown produce is increasing at a rate of approximately 20% each year in the United States (NRC report). The National Research Council report (Berenbaum et al., 2000) suggested that there is no indication that chemical pesticides will be abandoned in the near future. The committee associated with the report concluded that chemical pesticides will continue to play a significant role in US agriculture for at least another decade because of two major factors:
Effective and affordable alternatives to crop management chemicals are not universally available
Environmental compatibility and safety of newer crop management chemicals is increasing.
Reluctance of some countries and people to accept the use of genetically modified foods will also result in a continued reliance on the use of crop management chemicals for controlling plant diseases, weed species and insects in the foreseeable future.
Due to the continuing use of crop management chemicals in US agriculture there needs to be a continued improvement in the methodology used for the extraction and analysis of these chemicals. Work associated with a previous Multi-State Regional project has indicated that solid phase extraction (SPE) techniques can be used for the extraction of pesticides at one site with shipment of disks to a second analytical laboratory with minimal losses (Mueller et al., 2000). This technique has been tested with a variety of pesticides. These SPE procedures seem to be generally applicable, although some pesticides such as bifenthrin, chlorpyrifos and chlorothalonil, gave low recoveries from water (Mersie et al., 2002).
SPE extraction disks have been available for many years and they have several advantages in that they are particularly effective when extractions from large volumes of water with a corresponding increase in sensitivity are needed. There are several different types of disks currently available for different compounds. The use of these disks can eliminate the need for large amounts of organic solvents during the extraction procedure. Several problems have been associated with the use of these disks especially in field situations. These problems include the need for glassware for an extraction manifold which can be easily broken, realignment of the disk at a cooperating laboratory after the disk has been transported from the extraction site to the site of analysis even when laboratories have the same type of manifold, and the need to pre-filter turbid surface water samples prior to disk extraction.
New approaches to the use of solid phase extraction may eliminate problems noted in earlier research (Mueller et al., 2000, Senseman et al., 2003). Companies are continually introducing new products to be used in the extraction of various crop management chemicals from water which could alleviate some of the problems known in extraction procedures. It is necessary to investigate these new products and develop procedures which can be utilized throughout the world to obtain reliable accurate results. Testing of these materials across a multidisciplinary interlaboratory group and transporting these materials across state and regional borders provides the basis for the widespread utilization of these procedures for various applications while proving the validity and robustness of the procedures. Research concerning the applicability, robustness, and validity of a new analytical procedure is necessary before a procedure can be widely adapted for use in the analysis of crop management chemicals. The research proposed in this project will have a significant impact on the development of better and more environmentally friendly procedures while developing methods that can be used in remote field situations, where laboratory and analytical equipment for analysis may be unavailable.
The added advantage of this research is that it will be applicable to many important environmental chemicals. These chemicals may include pesticides as well as mycotoxins, plant growth regulators, and animal and secondary plant products which are associated with agricultural operations. The research is also applicable to various industrial chemicals associated with water resources.
The proposed research is appropriate to two of the goals outlined for the Southern Region Priority areas for Multi-State Research activities. These goals are: Goal 4. Greater Harmony between Agriculture and the Environment and Goal 5. Enhanced Economic Opportunity and Quality of Life for American. The improvement in analytical techniques for the analysis of crop management chemicals is important to air, soil and water resource conservation and enhancement, natural resource and ecosystem management, environmental policies and regulations, risk management and assessment in agricultural systems, and agriculture-related social and consumer concerns which are associated with these Goals. To accomplish these goals we have to be able to provide valid and sensitive analytical techniques for the presence of crop management chemicals upon which the general public and our stakeholders can rely. The development of new and improved methodology for the detection, extraction and analysis of crop protection chemicals as well as other chemicals associated with agricultural operations must be conducted by a multidisciplinary interlaboratory group. The reasons for this are often illustrated when one laboratory is unable to reproduce methods published by a second laboratory. The use of an interlaboratory group in method development allows for the identification of problems in the early stages of method development. The time involved in the development of new EPA and FDA methods illustrates how slow this process can be. Their methods must be extensively tested in multiple laboratories prior to their approval. The group assembled to conduct this research has different research emphasis areas such as crop, soil and plant sciences, pesticide research, watershed research, biochemistry, and water quality and environmental toxicology. This mix provides a good basis of individuals with knowledge to identify potential problem chemicals which can be incorporated into the research. The soil and water resources associated with member sites also provide different climatic and geological sites for testing of procedures. For example, research in a previous multistate project showed that Puerto Rico had problems related to high humidity when compared to Texas and methods were amended to obtain a final method that was amenable to both sites. This type of collaborative development is expected in the proposed research. The consequences of not conducting this research will be that the adaption of more environmentally friendly extraction and analysis methods will be slowed.
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