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6 SAMPLE ANALYSIS TOOLS for VOCs, SVOCS, and PESTICIDES

6.1 IN-SITU ANALYSIS

6.1.2 Laser-Induced Fluorescence

Use: Laser-Induced Fluorescence (LIF) analysis is performed beneath the ground surface to identify aromatic hydrocarbons with three or more benzene rings.

Description:

LIF uses the light emission from atoms or molecules to quantify the amount of the emitting substance in a sample. Fluorometry is a spectroscopic technique in which the electronic state of a molecule is elevated by absorption of electromagnetic radiation. Enchanted sensitivity is achievable because the fluorescence signal has a very low background. When the molecule returns to its ground state, radiation is emitted to produce a distinctive excitation and emission spectrum. Instruments used for fluorometric analysis contain four basic components:

  1. Source of excitation energy (such as UV (see 6.2.12), laser, x-ray (see 7.1.3)).
  2. Detector to measure photoluminescence.
  3. Pair of filters or monochromators for selecting the excitation and emission wavelengths.

Analytes:

5. PAHs
11. TPHs

Media:

Soil/Sediment Water Gas/Air
ADEQUATE BETTER Not Applicable
Selectivity: Technique measures the contaminant indirectly.
Susceptibility to Interference: Medium.
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
BETTER ADEQUATE BETTER ADEQUATE
Quantitative Data Capability: Data become quantitative with additional effort.
Technology Status: Commercially available and routinely used field technology.
Certification/Verification: Technology has 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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