Dense Nonaqueous Phase Liquids (DNAPLs)
Detection and Site Characterization
- Overview
- Policy and Guidance
- Chemistry and Behavior
- Environmental Occurrence
- Toxicology
- Detection and Site Characterization
-
- Treatment Technologies
- Conferences and Seminars
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Halogenated Alkanes
Carbon Tetrachloride
Carbon Tetrachloride(CT) is a volatile chlorinated organic and as such is subject to most standard characterization and analytical techniques used on this class of chemicals. Methods such as vertical profiling, membrane interface probe, and standard GC/MS are discussed in the main section for DNAPLs detection and site characterization.
Diffusion Samplers
While Diffusion Samplers have been used mostly for chlorinated ethenes and BTEX, they have been found to work for CT (ITRC 2004).
Laboratory Methods
Analysis of CT can be performed using standard analyses such as SW-846 methods 8021b,
8260b
, 8260c
, and 8261a
Chapter 7 in ATSDR (2005) describes analytical methods that are available for detecting, measuring, and/or monitoring CT, its metabolites, and other biomarkers of exposure and effect to CT.
Field Screening Methods
Given its Henry's constant, carbon tetrachloride should be detectable using headspace analysis with a field GC. Standards should be run to verify detection limit requirements. The photoionization energy for carbon tetrachloride is 11.47 eV (EPA 1994). If a PID detector is used, then the lamp must be 11.7 eV.
Draeger markets tubes for carbon tetrachloride. They have sensitivities of 0.1 to 5 ppm and 1 to 15 ppm. Phosgene is indicated with approximately the same sensitivity, and it is impossible to measure carbon tetrachloride in the presence of phosgene. Other chlorinated hydrocarbons are also indicated, but only when they occur in higher concentrations.
GasTec also markets tubes for carbon tetrachloride. They have sensitivities of 2.5 to 60 ppm, 0.5 to 2.5 ppm, 5 to 12 ppm, and 0.25 to 5 ppm. The following compounds can interfere at the given concentrations: hydrogen chloride (100 ppm), chlorine (50 ppm), bromine (50 ppm), methyl bromide (100 ppm), 1,1,1-trichloroethane (100 ppm), and chloropicrin. Vinyl chloride, methylene chloride, chloroform, tetrachloroethene, and trichloroethene do not interfere.
References
Standard Operating Procedure # 2114: Photoionization Detector HNU
U.S. EPA, Emergency Response Team, 16 pp, 1994
This document contains an extensive list of chemicals with their photoionization potentials.
Technical and Regulatory Guidance for Using Polyethylene Diffusion Bag Samplers to Monitor Volatile Organic Compounds in Groundwater
Interstate Technology & Regulatory Council (ITRC). DSP-3, 78 pp, 2004
Test Methods for Evaluating Solid Waste, Physical/Chemical Methods
U.S. EPA, SW-846 on line