| 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:
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Limitations:
ASTM Standards/EPA Methods:
No applicable ASTM standards or EPA methods are cited for this technology.
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