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Dense Nonaqueous Phase Liquids (DNAPLs)

Detection and Site Characterization

Halogenated Alkanes

1,1,2-Trichloroethane

1,1,2-Trichloroethane(1,1,2-TCA) is a volatile halogenated organic compound and as such is subject to most standard characterization and analytical techniques used on this class of chemicals. Methods such as vertical profiling, dyes, and standard GC/MS are discussed in the main section for DNAPLs detection and site characterization.

Diffusion Samplers

1,1,2-TCA contaminated groundwater can be sampled by Diffusion Samplers (ITRC 2004).

Laboratory Methods

Analysis of 1,1,2-TCA can be performed using standard analyses such as SW-846 methods 8021b, 8260b, and 8260c. The Agency for Toxic Substances and Disease Registry's toxicological profile for 1,1,1-TCA contains a discussion of laboratory analytical methods for this compound.

Field Screening Methods

Draeger makes a detection tube for trichloroethane. The detection range is 50 to 600 ppm, and the tube is sensitive to other chlorinated hydrocarbons. Aromatic compounds affect its sensitivity.

GasTec also makes a detector tube for 1,1,2-TCA. The lower detection limits are 200 to 750 ppm. Like the Draeger tube, it is sensitive to other compounds.

1,1,2-TCA should be detectable using headspace analysis with a field GC. Standards should be run to verify detection limit requirements. If the GC uses a photoionization detector (PID) instead of an electron capture detector (ECD), the lamp must be 11.7 eV as the standard 10.6 eV lamp will not ionize 1,1,2-TCA, which has an ionization energy of 11.0 eV (RAE Systems 2007). This would also be true for an organic vapor analyzer using a PID.

References

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