U.S. Environmental Protection Agency, 2007, Method 1699: Pesticides in water, soil, sediment, biosolids, and tissue by HRGC/HRMS: USEPA, Washington, DC, EPA-821-R-08-001, 96 p.
Brief Method Summary
This method involves extraction of the sample using procedures that vary based on the media being analyzed. Extracts are macro-concentrated using rotary evaporation, a heating mantle, or a Kuderna-Danish evaporator. Extracts to be injected into the HRGC/HRMS are concentrated to a final volume of 20 uL using nitrogen evaporation (blowdown). Extracts of aqueous, solid or mixed phase samples are cleaned up using an aminopropyl SPE column followed by a microsilica column. Extracts may be further cleaned up using gel permeation chromatography (GPC) or solid-phase cartridge techniques. Extracts in which the organo-chlorine pesticides only are to be determined may be further cleaned up using silica gel, Florisil, or alumina chromatography. Immediately prior to injection, a labeled injection internal standard is added to each extract and an aliquot of the extract is injected into the GC. The analytes are separated by the GC and detected by a high-resolution (>8,000) mass spectrometer. Two exact m/z's for each pesticide are monitored throughout a pre-determined retention time window. An individual pesticide is identified by comparing the GC retention time and ion abundance ratio of two exact m/z's with the corresponding retention time of an authentic standard and the theoretical or acquired ion-abundance ratio of the two exact m/z's. Quantitative analysis is performed in one of two ways using SICP areas.
Scope and Application
This method is for determination of selected organochlorine, organo-phosphorus, triazine, and pyrethroid pesticides in multi-media environmental samples by HRGC/HRMS.
Applicable Concentration Range
Variable based on analyte and media
Interferences
Solvents, reagents, glassware, and other sample processing hardware may yield artifacts, elevated baselines, and/or lock-mass suppression causing misinterpretation of chromatograms. Specific selection of reagents and purification of solvents by distillation in all-glass systems may be required. Where possible, reagents are cleaned by extraction or solvent rinse. Proper cleaning of glassware is extremely important, because glassware may not only contaminate the samples but may also remove the analytes of interest by adsorption on the glass surface. All materials used in the analysis must be demonstrated to be free from interferences by running reference matrix method blanks initially and with each sample batch. Interferences co-extracted from samples will vary considerably from source to source, depending on the diversity of the site being sampled. Interfering compounds may be present at concentrations several orders of magnitude higher than the pesticides. Frequently encountered interferences are chlorinated biphenyls, chlorinated and brominated dibenzodioxins and dibenzofurans, methoxy biphenyls, hydroxydiphenyl ethers, benzylphenyl ethers, brominated diphenyl ethers, polynuclear aromatics, and polychlorinated naphthalenes. Because very low levels of pesticides are measured by this method, elimination of interferences is essential. The cleanup steps given in the method report can be used to reduce or eliminate these interferences and thereby permit reliable determination of the steroids and hormones. Reusable glassware should be numbered to associate each piece with the processing of a particular sample. This will assist in tracking possible sources of contamination for individual samples, identifying glassware associated with highly contaminated samples that may require extra cleaning, and determining when glassware should be discarded. Refer to the method report for interferences specific to biosolids and tissue.
Quality Control Requirements
Each laboratory that uses this method is required to operate a formal quality assurance program. The minimum requirements of this program consist of an initial demonstration of laboratory capability, analysis of samples spiked with labeled compounds to evaluate and document data quality, and analysis of standards and blanks as tests of continued performance. Laboratory performance is compared to established performance criteria to determine if the results of analyses meet the performance characteristics of the method.
Sample Handling
Collect samples in amber glass containers following conventional sampling practices; collect field and trip blanks as necessary to validate the sampling. Each media being sampled require specific handling procedures; refer to the method report for each description.
Maximum Holding Time
Aqueous samples:Extract within 7 d of collection; analyze w/n 40 d of extraction.
All other sample media:Extract and analyze within 1 yr. Sample storage >14 d, hermetically seal sample container or adjust final concentration based on
The accuracy and precision were determined after analysis of 4 samples in reagent water at a single laboratory.
For beta-endosulfan, disulfoton, and methamidophos, biosolid data is presented in NEMI since reagent water data was not available.
For permethrin, the elution order of cis/trans permethrin is unknown, refer to the method report for performance data.
Detection Level Note:
The detection limits in this method are dependent on the level of interferences rather than instrumental limitations and were determined using methods described in 40 CFR 136, appendix B. The detection limits presented are those that can be determined in the absence of interferences.
For permethrin, the elution order of cis/trans permethrin is unknown, refer to the method report for detection limits.
Revision
PDF/Link
December 2007
The Water Quality Portal contains
sample results from
sites that use this method.
