InterPhase's integrated mobile laboratory vans (IMV), which hold laboratory grade gas chromatograph for analysis of samples. These compact sampling and analytical units provide most cost effective, highly mobile and flexible environmental contamination detection and site assessment service. The methods applied to the integrated mobile laboratory van have been designed to maximize accuracy and minimize contamination and are in accordance with the California Regional Water Quality Control Board (CRWQCB) Well Investigation Program (WIP).
Soil gas samples are taken and analyzed within 30 minutes of collection in order to preserve the integrity of the vapor sample. The procedure of analysis is based on USEPA Methods 8015 and 8020, which analyze for aromatic species, methane (low concentrations), common solvents such as ketone and alcohol, and substances such as gasoline, diesel, and JP fuels. |
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The analytical system in this van is comprised of traditional stationary laboratory grade gas chromatographs(GC) configured with both capillary and packed columns and a combination of compound-selective detectors. The GC shown here for the analysis of soil gas and ambient air is a Hewlett-Packard 5890A instrument. A total of three detectors are used in this GC for vapor and air analyses. These detectors include photo ionization detector (PID), flame ionization detector (FID), and thermal conductivity detector (TCD).
Below are commonly requested target analytes for InterPhase Mobile Van Laboratory.
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MODIFIED EPA METHOD 8015
Acetone
Ethanol
Methyl ethyl ketone (MEK)
Methyl iso-butyl ketone (MIBK)
Methyl tert-butyl ether (MTBE)
Total Volatile Hydrocarbons (TVH), C4-C10 (gas range)
MODIFIED EPA METHOD 8020 (BETX)
Benzene
Toluene
Ethylbenzene
Total xylenes
FIXED/BIOGENIC GASES
CO2, O2, N2, CH4
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Mobile Trailer Laboratories (MTL)
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InterPhase's stationary mobile laboratories, used to provide on-site analyses, are housed in custom-built, air conditioned trailers. The trailer laboratories are stand-alone vehicles that operate separately from the direct-push rigs, thereby allowing efficient operation of both. Each MTL is equipped with a Varian 3400, temperature programmable gas chromatograph (GC) with two capillary columns and three detectors. Computer controlled automatic sample injection system raises the accuracy, precision and productivity of analysis. Cryogenic cooling of the column is provided to below 0° C.
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MODIFIED EPA METHOD 8010/8020 OR 8021
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carbon tetrachloride
chloroethane
chloroform
1,1-dichloroethane
1,2-dichloroethane
1,1-dichloroethene
cis-1,2-dichloroethene
trans-1,2-dichloroethene
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dichloromethane
tetrachloroethene
1,1,1,2-tetrachloroethane
1,1,,2,2-tetrachloroethane
1,1,1-trichloroethane
1,1,2-trichloroethane
trichloroethene
vinyl chloride
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benzene
toluene
ethylbenzene
xylenes
trichlorofluoromethane
dichlorodifluoromethane
1,1,2-trichloro-trifluoroethane
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The major service of InterPhase’s MTL is to perform three simultaneous analyses by splitting the injection to two chromatographic columns leading to three detectors. The first column performs two analyses which are best described by a modified EPA Method 8010 and 8020. EPA Method 8010 is an analysis for volatile chlorinated hydrocarbons and 8020 is an analysis for aromatic species.
A third method of soil gas analysis is best described as a modified EPA Method 8015. The EPA 8015 protocol is suitable for the analysis of volatile hydrocarbons, including methane (low concentrations), non-chlorinated solvents such as ketones and alcohols, and substances such as gasoline, diesel, and JP fuels. In addition, the sum of peak areas over certain range provides a measure of total volatile (or petroleum) hydrocarbons (TVH or TPH). Also, the simultaneous analyses on two different columns provide target confirmation for every sample. |
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The major modification to the EPA Methods is that direct gas sample injection, instead of purge & trap device, is used to introduce sample into GC. Also, the target compound lists are subsets of the EPA methods. InterPhase’s MTLs have adopted the following measures to provide better precision, accuracy, and reliability of analysis.
-Gas standards are employed rather than liquid-solution standards.
-Samples are introduced to GC by filling into precision loops that are connected to automatic switching valves.
-Surrogates are automatically injected via a precision-volume loop for each GC run.
-Cryogenic cooling of the column oven by injecting liquid carbon dioxide is used to bring the GC starting temperature down to 0° C. The lower-than-ambient starting temperature enables the GC to separate the light compounds more efficiently, and provides a better peak shape.
One MTL is equipped with a second GC and is capable of analyzing fixed gases and hydrogen sulfide simultaneously, in addition to the above-mentioned three methods.
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