Miniature Membrane Inlet Gas Chromatograph for Cone PenetrometersEPA Contract Number: 68D99040
Title: Miniature Membrane Inlet Gas Chromatograph for Cone Penetrometers
Investigators: Dvorak, Michael
Small Business: Dakota Technologies Inc.
EPA Contact: Richards, April
Project Period: September 1, 1999 through March 1, 2000
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (1999) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , SBIR - Monitoring , Small Business Innovation Research (SBIR)
Description:Dakota Technologies, Inc. (DTI) has successfully adapted three different gas chromatography (GC) detectors (photoionization, halogen-specific, and electron capture) for operation inside a cone penetrometer. They enable field screening for volatile organic compounds (VOCs) at concentrations below the mg/kg level in soil and the mg/L level in groundwater. A heated microporous membrane in the side of the soil probe transfers VOCs from the soil formation into a carrier gas stream leading to the detectors; data are collected continuously as the probe is advanced into the ground. In this Phase I project, DTI will achieve exceptional sensitivity and specificity by making GC measurements while the cone is stopped. A hollow fiber permeation membrane, a sorbent preconcentrator, and a short chromatographic column will be introduced between the microporous membrane and the detector. The result will be the complete functionality of a sophisticated gas chromatograph in a downhole configuration. In Phase II, DTI expects to specifically detect benzene, toluene, trichloroethylene, perchloroethylene, and methyl tertiary butyl ether in groundwater at concentrations down to 1 µg/L, which is less than their maximum contaminant levels (MCLs). The cycle time, measured from when the probe is advanced to the depth of interest to the completion of the elution/detection phase, is projected to be less than 3 minutes.
The outcome of the Phase I and Phase II work will be a fully functional gas chromatograph that can be operated inside a cone penetrometer probe. It will allow rapid, automatic, specific, and sensitive measurements of VOCs in the subsurface without any need to bring material to the surface. Widespread commercial applications are envisioned, particularly in situations where groundwater sources are threatened by subsurface organic contamination. The technology will substitute and displace measurements currently performed in offsite laboratories on samples extracted from the ground.