| Use: | Determines the masses of atoms or molecules found in a solid, liquid, or gas. Often
used in combination with gas chromatography (see 9.1.3) NOTE: Due
to instability of certain explosives, mass spectrometry is not a preferred option.
However, low concentrations of thermally sensitive explosives can be safely analyzed using
proper procedures. See 6.2.7 for use with VOCs, SVOCs, and pesticides. |
Description:
A mass spectrometer produces charged particles (ions) from the chemical substances that are to be analyzed and then uses electric and magnetic fields to measure the mass (weight) of the charged particles. Distinctive mass/charge ratios allow for identification of compounds, while the magnitude of ion currents at various mass settings is related to concentration. Major components of the mass spectrometer include: (1) the inlet system, (2) the ion source, (3) the electrostatic accelerating system, and (4) the detector and readout system that gives a mass spectrum recording the numbers of different ions.
When a sample is introduced into the mass spectrometer, electron bombardment causes the parent molecule to lose an electron and form a positive ion. Some of the parent ions also are fragmented into characteristic daughter ions. All of the ions are accelerated, separated, and focused on an ion detector by means of either a magnetic field or a quadrupole mass analyzer. Using microgram quantities of pure materials, the mass spectrometer yields information about the molecular weight and presence of other atoms within the molecule, such as nitrogen, oxygen, and halogens. The most favorable routes for decomposition provide the most intense peaks in the mass spectrum. High resolution spectra contain so much data that computers are used for molecular structure analysis and acquisition of data in a form easily assimilated by the operator.
Analytes:
10. Explosives
Media:
| Soil/Sediment | Water | Gas/Air |
| Requires extraction to liquid or gas phase | Requires extraction to liquid or gas phase | ADEQUATE |
| Selectivity: | Technique measures the specific contaminant indirectly. |
| Susceptibility to Interference: | High. |
| Detection Limits : | 10-100 ppm (soil); 0.5-10 ppm (water). |
| Turnaround Time per Sample: | Minutes. |
| Applicable To: | |||
| Screen/Identify | Characterize Concentration/Extent | Cleanup Performance | Long-Term Monitoring |
| ADEQUATE | ADEQUATE | ADEQUATE | ADEQUATE |
| 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: | Most expensive. |
Limitations:
ASTM Standards/EPA Methods:
No applicable ASTM standards or EPA methods are cited for this technology.
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