Comparison of downhole and surface sampling for the determination of volatile organic compounds (VOCs) in ground water
- Oregon Dept. of Environmental Quality, Portland (United States)
- Oregon Graduate Inst. of Science and Tech., Beaverton (United States)
- Geological Survey, Trenton, NJ (United States)
- Picatinny Arsenal, Dover, NJ (United States)
The relative precision and accuracy of sampling and analysis methods for the determination of trace concentrations of volatile organic compounds (VOCs) in ground water were compared. Samples were collected from a well containing nanogram-per-liter (ng/L) to microgram-per-liter ({mu}g/L) levels of VOCs. A Keck helical rotor submersible pump was used to collect samples at the surface for analysis by purge and trap (P and T) and for analysis by adsorption/thermal desorption (ATD). Downhole samples were collected by passing water through an ATD cartridge. Although slight spontaneous bubble outgassing occurred when the water was brought to the surface, the relative precisions and comparabilities of the surface and downhole methods were generally found to be equivalent from a statistical point of view. A main conclusion of this study is that bringing sample water to the surface for placement in VOC vials (and subsequent analysis by P and T) can be done reliably under many circumstances. However, care must still be taken to prevent adsorption losses and cross contamination. Samples subject to strong bubble outgassing will need to be handled in a special fashion (e.g., by downhole ATD) to minimize volatilization losses. Additionally, the high sensitivity of the ATD method allows lower detection limits than are possible with P and T. For example, several compounds present at the ng/L level could be determined with confidence by ATD, but not by P and T.
- OSTI ID:
- 5245538
- Journal Information:
- Ground Water Monitoring Review; (United States), Vol. 12:1; ISSN 0277-1926
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GROUND WATER
CHEMICAL ANALYSIS
SAMPLING
VOLATILE MATTER
ACCURACY
COMPARATIVE EVALUATIONS
CONTAMINATION
DEGASSING
ECOLOGICAL CONCENTRATION
QUANTITY RATIO
WATER POLLUTION MONITORS
EVALUATION
HYDROGEN COMPOUNDS
MATTER
MEASURING INSTRUMENTS
MONITORS
OXYGEN COMPOUNDS
WATER
540220* - Environment
Terrestrial- Chemicals Monitoring & Transport- (1990-)