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6 SAMPLE ANALYSIS TOOLS for VOCs, SVOCS, and PESTICIDES

6.2 EX-SITU ANALYSIS

6.2.14 UV-Visible Spectrophotometry

Use: Spectrophotometry encompasses a number of techniques involving measurement of the absorption spectra of narrow band widths of radiation.

Description:

A simple spectrophotometer consists of the following:

  1. Radiation source.
  2. Monochromator containing a prism or grating which disperses the light so that only a limited wavelength or frequency range is allowed to irradiate the sample.
  3. Detector which measures the amount of light transmitted by the sample.

Visible spectrometry covers the range of 380 to 780 nm and uses tungsten lamps as the radiation source, glass or quartz prisms in the monochromators, and photo-multiplier cells as the detector.

UV spectrometers cover the region from 200 to 400 nm and usually use a hydrogen lamp as a radiation source, a quartz prism in the monochromator, and a photo-multiplier tube as the detector.

Requires extraction to a liquid that does not adsorb UV (hexane).

Analytes:

1. Non-Halogenated VOCs 3. Halogenated VOCs 5. PAHs

Media:

Soil/Sediment Water Gas/Air
Requires extraction to a liquid or gas phase BETTER ADEQUATE
Selectivity: Technique measures a part of the compound.
Susceptibility to Interference: High.
Detection Limits : 100-100 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 limited field experience.
Certification/Verification: Technology has not participated in CalEPA certification and/or CSCT verification program.
Relative Cost per Analysis: Mid-range expense.

Limitations:

EPA Methods:

9065 Phenolics (Spectrophotometric, Manual 4-AAP with Distillation).
9067 Phenolics (Spectrophotometric, Manual MBTH with Distillation).
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