Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2005
Publication Date: 6/29/2005
Citation: Riley, M.B., Dumas, J.A., Gbur, E.E., Massey, J.H., Mattice, J.D., Mersie, W., Mueller, T.C., Potter, T.L., Senseman, S.A., Watson, E. 2005. Pesticide extraction efficiency of two solid phase disk types ofter shipping. Journal of Agricultural and Food Chemistry. 53:5079-5083. Interpretive Summary: To address concerns about adverse water quality impacts that may result from agricultural pesticide use and evaluate management practices designed to keep impacts to a minimum, robust analytical methods for measurement of residues in water samples are needed. Ideally methods should be validated by inter-laboratory testing to ensure that measurements are accurate, representative and reproducible. This is the focus of the multi-state southern region project, S-1011: Water Quality Methodology for Crop Protection Chemicals. Participants include academic pesticide research groups located in Texas, Virginia, Arkansas, South Carolina, Mississippi, Tennessee, Kentucky and Puerto Rico and the USDA-ARS Southeast Watershed Laboratory. Annual inter-laboratory collaborations are conducted which systematically evaluate methods for trace level pesticide residue analysis of water. In the past year, the groups compared the performance of two commercially available products for the extraction and enrichment of pesticides from water. One of the products, Empore' Discs was the subject of a prior inter-laboratory study. Results showed that pesticide recoveries from water were high and that results were reproducible, but some laboratories noted that some filter discs clogged during sample extraction. This is a significant limitation in their general use for analysis of environmental water samples. In the current study, pesticide recoveries from water with Empore' disks were compared to a new product, Speedisks' C18XF. Results indicate that Speedisks' C18XF could be used as an alternative to Empore' disks with no significant losses in recovery. Speedisks' C18XF are enclosed in a plastic housing so they can be used more easily in remote sampling sites and Speedisks' C18XF design makes them much less susceptible to clogging. These are significant advantages which should be of interest to laboratories throughout the country who are involved in testing water samples for pesticides.
Technical Abstract: An interlaboratory study was conducted to compare pesticide recovery of Empore' C18 and Speedisks' C18XF solid-phase extraction disks. Four pesticides were used for the comparison of the two disk extraction materials: atrazine, diazinon, metolachlor, and tebuconzole. These pesticides were chosen to provide a range of physicochemical properties. Water samples were extracted onto the disk types and shipped to a cooperating laboratory for elution and analysis. Mean recovery from Empore' disks was atrazine 95%, diazinon 91%, metolachlor 92%, and tebuconazole 83% while recovery from Speedisks' C18XF was atrazine 89%, diazinon 87%, metolachlor 86%, and tebuconazole 79%. Means were not statistically different, but there was more variability with Speedisks' C18XF compared to Empore' disks. Results indicate that Speedisks' C18XF could be used as an alternative to Empore' disks with no significant losses in recovery. Speedisks' C18XF are enclosed in a plastic housing so they can be used more easily in remote sampling sites.