Title | Guidance for the WDOE NWTPH-Dx Method for Testing Groundwater: Silica Gel Cleanup Protocol Revision |
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Guidance for the WDOE NWTPH-Dx Method for Testing Groundwater: Silica Gel Cleanup Protocol Revision (Number of pages: 49) (Publication Size: 1354KB)
Appendix B. Analytical QC Tables (16 pages) (865KB) Appendix C. Data Validation Report (12 pages) (637KB)
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Author(s) | Hobbs, W., K. Bailey, J. Protasio, and C. Frans | ||||||
Description | In 1997, the Washington State Department of Ecology (Ecology) published analytical methods for analyzing total petroleum hydrocarbons (TPH) (NWTPH; Ecology 1997). Under guidance by Ecology’s Toxic Cleanup Program (TCP), a silica gel cleanup (SGC) step can be employed where groundwater may contain a component of naturally occurring polar compounds that may interfere with the NWTPH analysis for diesel range organics (DRO). The goal of this project was to provide an updated protocol on how laboratories use silica gel cleanup (SGC) on groundwater samples contaminated with weathered DRO. Twenty-three regional labs accredited by Ecology for the NWTPH method were surveyed to determine what SGC protocols are being used. Thirteen labs responded, and current protocols varied across labs. Manchester Environmental Laboratory (MEL) wrote and tested a revised SGC protocol based on published silica gel column approaches and EPA Method 3630. The revised protocol also incorporated a reverse surrogate of decanoic acid to evaluate the efficacy of removing polar compounds. Seven of the 13 contract labs agreed to participate in a paid inter-laboratory comparison study with MEL to evaluate the revised protocol. The results of the inter-lab study showed that the revised SGC protocol is repeatable and reproducible among the labs. TCP should begin disseminating the revised protocol internally to site managers and consider revising the NWTPH method guidance. |
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NOTES | Erratum for revised version (April 2024): Table 2 updated to include Friedman & Bruya, Inc.'s silica gel cleanup method information. | ||||||
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Contact | William Hobbs at 564-669-3028 or william.hobbs@ecy.wa.gov | ||||||
Keywords | polar metabolite, hydrocarbon, NWTPH, NWTPH-Dx analytical method, Silica Gel Cleanup (SGC), Diesel-range organics, Silica Gel | ||||||
RELATED PUBLICATIONS | Title:
Quality Assurance Project Plan: Guidance for the WDOE NWTPH-Dx Method for Testing Groundwater Implementation Memorandum No. 23: Concentrations of Gasoline and Diesel Range Organics Predicted to be Protective of Aquatic Receptors in Surface Waters Environmental Effects-Based Concentrations for Weathered Diesel-Range Organics: Toxicity in Marine Water and Freshwater Addendum to Quality Assurance Project Plan: Environmental Effects-Based Concentrations for Total Petroleum Hydrocarbons (TPH) in Marine Water and Freshwater Environmental Effects-Based Concentrations for Total Petroleum Hydrocarbons (TPH): Toxicity in Marine Water and Freshwater Quality Assurance Project Plan: Environmental Effects-Based Concentrations for Total Petroleum Hydrocarbons (TPHs) in Marine Water and Freshwater |
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