United States Environmental Protection Agency National Exposure Research Laboratory Research Triangle Park, NC 27711 Research and Development EPA/600/SR-97/110 January 1998 Project Summary Development of Analytical Methods for Specific Lawn- Applied Pesticides in House Dust Marcia G. Nishioka, Hazel M. Burkholder, Marielle C. Brinkman, and Sydney M. Gordon The methods developed in this pro- gram were designed for detection of specific lawn-applied pesticides in house dust and in polyurethane foam (PDF) sleeves. PDF sleeves are used in a dislodgeable surface residue col- lection device, the PUF Roller. The method developed for the herbicide acids was applicable, as well, to the analysis of pentachlorophenol and 2,4-dichlorophenol. The method de- veloped for the dinitro-aniline herbi- cides was also applied successfully to the analysis of several thiophos- phate insecticides and a chlorinated fungicide. Methods developed here provided recoveries better than 80% at spike levels that approximate house dust levels. The methods incorporated sur- rogate recovery standards and inter- nal standards (for quantification) that are tailored to the specific analyte classes. This use of structurally simi- lar surrogate recovery standards and internal standards provides a greater degree of confidence in the methods when they are used for field samples: the recovery of surrogates gives a clear picture of the expected analyte recovery. Structurally similar internal standards compensate for the minor chromatographic differences between samples and standards and these more accurately reflect the chroma- tography of the analytes. The methods that were developed are rigorous and rugged, and per- formed well when applied in field stud- ies of simulated track-in of lawn- applied pesticides into the home. Recoveries of surrogate recovery stan- dards were generally greater than 90% in these studies. This Project Summary was developed by EPA's National Exposure Research Laboratory, Research Triangle Park, NC, to announce key findings of the re- search project that is fully documented in a separate report of the same title (see Project Report ordering infor- mation at back). Introduction House dust appears to be a long-term sink within the home for pollutants, in gen- eral, and pesticides, in particular. Scien- tists, and now homeowners, are interested in the concentrations of hazardous pollut- ants adsorbed on house dust. Young chil- dren appear to ingest significant quanti- ties of dust while crawling and playing on carpeted surfaces. With their less sophis- ticated immune systems and high degree of developmental change, younger chil- dren may be at greater risk to ingestion of contaminated dust than older children or adults. House dust is a more complex matrix than soil or plant material. Debris from human skin and human activities (e.g. food, household cleaners) combined with combustion source-derived pollutants will be encountered in the house dust. Poten- tial chemical interferences in the analysis of pesticides in dust include, but are not limited to, fatty acids, lipids, phenols, poly- cyclic aromatic hydrocarbons, and carpet additives. The ease in applying standard soil analysis methods to house dust samples for outdoor-applied pesticides will be compromised further by pesticide lev- ------- els that are expected to be significantly lower due to the dilution that occurs dur- ing any migration process. Therefore, methods suitable for outdoor levels are unlikely to be suitable for lower indoor levels in a specific matrix like house dust. Results and Discussion Two different analyte derivatization methods were developed and used on this program, methylation with diazo- methane and pentafluorobenzyl bromide (PFBBr) derivatization. Methylation of analytes with at least two chlorines pro- vides sufficient sensitivity for detection by GC/ECD (gas chromatography with elec- tron capture detection) of mid to low ppb concentration levels. Detection limits for the mono-chloro phenoxy herbicide acids can be as much as a factor of 1000-fold higher, compared to the di-chloro phe- noxy herbicide acids, with methylation and GC/ECD analysis. PFBBr derivatization offers the possibility of detection with en- hanced sensitivity for these mono-chloro herbicide acids. The analyte spike levels for studies involving methylation spanned a concen- tration range of 1000. Despite this wide concentration range, very similar recover- ies were achieved for all analytes; recov- eries were generally >85%. As seen from the study of recovery from PUF, the re- covery of the 2,4-D sodium salt was only slightly less than the recovery of the 2,4-D free acid. We conclude that these meth- ods are useful for recovery of herbicide salts that are typically applied to turf. For analyses using the PFBBr derivatization, the spike levels of the analytes were iden- tical and recoveries were similar (>85%). Conclusions Methods developed here provided re- coveries better than 80% at spike levels that approximate house dust levels. The methods incorporated surrogate recovery standards and internal standards (for quan- tification) that are tailored to the specific analyte classes. The methods that were developed were rigorous and rugged, and performed well when applied in field studies of simulated track-in of lawn-applied pesticides into the home. Recoveries of surrogate recovery standards were generally greater than 90% in these studies. Sonification was shown to be useful for extraction of both acidic herbicides and polar dinitro-aniline herbicides. This ap- proach was rapid and eliminated the need for solvent-intensive Soxhlet extraction. Extraction of PUF sleeves by manual squeezing of the PUF in a polyethylene zip-lock bag was shown to be an efficient method for obtaining an extract of trace dislodgeable surface residues. Due to the complexity of the house dust matrix, cleanup procedures had to be de- veloped with each method. With sample extract cleanup, analyses could be per- formed using relatively low-cost, automated GC/specific detector analyses, rather than higher-cost, GC/MS analyses. The cleanup procedures also reduced significantly the organic burden placed on GC columns, thus prolonging their lifetime and enhanc- ing their performance. Solid phase extrac- tion with disposable prepacked cartridges was shown to be an effective and efficient method of cleanup. Additional liquid parti- tion steps were used as necessary. Analyses of nine residential house dust samples for herbicide acids and penta- chlorophenol were carried out using the designated extraction and cleanup meth- ods and both GC/ECD and NCI GC/MS analyses. These analyses showed good agreement in quantification between the two techniques, and no detectable inter- ferences to the analytes of interest. Recommendations We recommend a further method development effort for the analyses of glyphosate in house dust. Degradation in GC column performance and/or detector performance was found with the method developed, indicating the need for devel- opment of an additional sample cleanup technique. This report was submitted in partial ful- fillment of Contract No. 68-DO-0007 by Battelle under the sponsorship of the U. S. Environmental Protection Agency. This work was conducted during the time pe- riod of October 1991 to September 1993, and was completed as of April 30, 1993. ------- Marcia G. Nishioka, Hazel M. Burkholder, Marielle C. Brinkman and Sydney M. Gordon are with Battelle, Columbus, OH 43201. Robert G. Lewis is the EPA Project Officer (see below). The complete report, entitled "Development of Analytical Methods for Specific Lawn- Applied Pesticides in House Dust," (Order No. PB9; Cost: $25.00, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: National Exposure Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati, OH 45268 BULK RATE POSTAGE & FEES PAID EPA PERMIT NO. G-35 Official Business Penalty for Private Use $300 EPA/600/SR-97/110 ------- |