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Environmental Services
In laymen's terms
Samples dealing with the environment are analyzed for low
level pollutants which are measured in parts per million or
parts per billion. To understand the term parts per million
imagine a dollar bill somewhere on a football field. For
a part per billion, think of that dollar bill in an area of
land that is the size of one thousand football fields. Your
job is to find that dollar bill, a seemingly impossible task.
However, if you approach this challenge scientifically and
methodically, you can find that piece of currency and maybe
some other goodies. First get a leaf blower and work the field
starting at the northwest end and blow all the debris toward
the southeast. When everything is collected in a mound,
search for the bill in it.
The environmental chemist follows this concept
in the laboratory. He takes a sample, be it water, soil,
air or waste, and follows specific procedures to concentrate
and isolate the pollutants. The type of procedure that
is used is dependent on the category into which the
environmental pollutant falls. The categories are based
on chemical properties and are as follows:
Volatiles - low boiling chemicals, include industrial solvents
Semi-volatiles - higher boiling chemicals such as pesticides and polychlorinated biphenyls(PCBs)
Metals – and their salts (e.g. iron and rust)
Volatiles
Because of their low boiling points volatiles
evaporate readily and present a challenge to the analytical
chemist since they can easily escape from the sample and be
lost. A sample which is analyzed for volatiles is always kept
closed to contain the pollutants. During the analytical
process, the pollutants are removed by agitating the sample
in a closed system with an inert gas. The agitation releases
the volatiles, which are then trapped on a special medium.
They are removed from the medium by heating and swept into
the analytical system where they are identified and quantified.
Because of the sensitivity of the procedure, great care is
exercised to prevent contamination from outside sources such
as laboratory solvents or automobile exhaust.
Semi-Volatiles
Pollutants called semi-volatiles are
removed from environmental samples by shaking them
with a solvent that does not mix with water.
Semi-volatiles prefer to be in the solvent and move
readily into it. The solvent is drained off and
evaporated over a hot water bath to concentrate the
pollutants into a small volume. A portion is injected
into the analytical system. Serious contamination
can result from careless handling of samples and,
in order to monitor cleanliness, laboratory blanks
are analyzed frequently.
Metals
Samples which are analyzed for metals
are digested with nitric acid to remove any
interferences and isolate the metals. Again
great care is taken to prevent contamination
which can result from improper handling.
In a nutshell
The analytical steps introduced above
are greatly simplified from what actually happens
in the laboratory. The analysis of environmental
pollutants involves costly equipment, highly
trained professionals and extensive quality control.
Environmental Analyses
Wastewater Analyses, 40 CFR Part 136
Total Toxic Organics
Semi-Volatiles, Method 625
Volatiles, Method 624
Metals
EPA Method 200.7
Mercury, EPA Method 245.1
Wet Chemistry
Acidity, total components
Alkalinity, total components
BOD
Boron
Bromide
BTU content
Carbon, organic(TOC)
COD
Chloride
Chromium, hexavalent(color)
Conductivity
Cyanide
Dissolved oxygen
Fluoride (distillation)
Fluoride
MBAS(surfactants)
Nitrogen, ammonia
Nitrogen, Kjeldahl
Nitrogen, nitrate
Nitrogen, nitrite
Fats, Oil & Grease(FOG)
pH
Phenol
Phosphorus
Silica
Solids, dissolved
Solids, suspended
Solids, total
Solids, volatile
Specific gravity
Sulfate
Sulfide
Sulfite
Turbidity
EPA SW-846, Office of Solid Waste
Organics Compounds, Methods 8260 & 8270
Semi-Volatiles Compounds
Volatiles Compounds
Herbicides
PCBs
PNAs
BTEX
Metals, Methods 6010 & 7470
RCRA Analyses, Methods 1311
Ignitability (flashpoint)
Corrosivity (Nace steel & pH)
Reactivity (CN * S)
Toxicity (leaching & analysis)
Air Analyses
EPA Method TO-1
EPA Method TO-2
PCBs
Total Suspended Particulates
Nuisance Dust
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