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6 SAMPLE ANALYSIS TOOLS for VOCs, SVOCS, and PESTICIDES

6.2 EX-SITU ANALYSIS

6.2.21 Amperometric and Galvanic Cell Sensor


Use: Ambient air quality monitoring of VOCs.

See 7.1.9 for use with metals.

Description:

Amperometric and galvanic cell sensors measure an electrochemical response when the sensor comes into contact with the analyte of interest. Each probe contains a sensor which is specifically sensitive to a particular gas or vapor. An internal pump draws an air sample into the analyzer. These sensors typically consist of electrodes in contact with an electrolyte-saturated insulator. Selective membranes allow the gas of interest to enter the insulator, and redox reaction on the sensing-electrode surface generates a current that is proportional to the analyte concentration. When an analyte is present, it will absorb to the thin-film sensor which undergoes a change in electrical resistance proportional to the mass of analyte absorbed onto its surface. This change is measured and converted to a vapor concentration that is displayed on the readout of the analyzer.

Analytes:

1. Non-Halogenated VOCs
3. Halogenated VOCs

Media:

Soil/Sediment Water Gas/Air
Requires extraction to gas phase Not Applicable BETTER
Selectivity: Technique measures a part of the compound.
Susceptibility to Interference: Medium.
Detection Limits : 100-1000 ppb (soil); 1-50 ppb (water).
Turnaround Time per Sample: Minutes.
Applicable To:
Screen/Identify Characterize Concentration/Extent Cleanup Performance Long-Term Monitoring
BETTER ADEQUATE BETTER BETTER
Quantitative Data Capability: Data become quantitative with additional effort.
Technology Status: Commercially available technology with moderate field experience.
Certification/Verification: Technology has not participated in CalEPA certification and/or CSCT verification program.
Relative Cost per Analysis: Least expensive.

Limitations:

ASTM Standards/EPA Methods:

No applicable ASTM standards or EPA methods are cited for this technology.


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