Sampling and Laboratory Analysis for Solvent Stabilizers - Environmental Investigation and Remediation - page 193

Anthropogenic pollutants

Naturally occurring chemicals

Spectrum of chemical classes, structures and conformations
sample water, air, extract

Extraction (if using chromatography)
or sample preparation/clean-up

Extractables Non-extractables

Separation (physical or signal)

Resolved Unresolved

Detection

Artifact

Native
compounds

Large portion of naturally occuring
and anthropogenic chemicals of
varied toxicity

Identification

TICs

Missed

unknowns

Ta r g e t
analytes

Recognizable
artifact

C.G. Daughton
U.S. EPA July 2002

FIGURE 4.1 Limitations and complexity of environmental chemical analysis. TICs = tentatively identii ed
compounds. (From Daughton, C.G., 2006, Pharmaceuticals as environmental contaminants: An overview of
the science. Paper presented at the Water Education Foundation Pacii c Conference. With permission.)

these cost less than conventional sampling. Performance data for sampling 1,4-dioxane are available
for most of these samplers. Polyethylene diffusion bag samplers have been studied extensively and
are widely used. Performance data for PDBs can be found online. *
This section briel y examines how some of these passive-diffusion samplers are used and how
their results compare for 1,4-dioxane sampling. Diffusion methods determine the concentration
from the mass of analyte per volume of sample in the same way as grab samples obtained from a
bailer or sampling pump; however, diffusion methods require that the volume within the sampler
comes into mass equilibrium with the groundwater outside the sampler. It is therefore necessary to
leave the samplers in the monitoring well for as long as two weeks.

* See the Interstate Technology & Regulatory Council Web site ( http://www.itrcweb.org/ ) or the EPA Hazardous Waste
Cleanup Information site ( http://www.clu-in.org ).