GLOSSARY OF TECHNICAL TERMS
This compound is considered the most toxic of the chemical family of
dioxins and furans. It is assigned the toxicity equivalent factor
(TEF) of "1", and all other dioxins and furans are assigned a TEF value
less than "1".
Adsorb To collect (a gas, etc.) in condensed form on a surface.
An analytical chemistry term referring to a measured portion taken from
a solution. When an aliquot of a sample solution is
analyzed, the concentration of the targeted compound in the original
solution can be calculated from those analysis results.
Analyte The targeted compound or element for which an analysis is being executed.
Electrical or chemical interferences with the signal coming from the
detector of an analytical instrument. The analyte must create a
signal in the detector which sufficiently overcomes these interferences
in order to be detected. In the case of dioxin/furan analysis,
the signal to noise ratio must be greater than 2.5 for all monitored
A quality assurance sample which is analyzed to ensure that any
contamination is known and can be accounted for. Contamination
may occur before, during or after the sampling or analysis testing
procedures. The primary contamination of concern is the analyte
or analytes that are being tested for. In dioxin/furan testing,
the method calls for a field blank because of the several different
solutions and pieces of equipment used in the testing. As an
example, a basic set of blanks normally analyzed in dioxin testing is
the method blank, field blank and trip blank.
Procedures that are prescribed by the dioxin/furan test methods to
check the performance of the analytical instrumentation. The
procedures involve the running of standards at different concentrations
and ensuring that the results are consistent with the predicted
CFR Code of Federal Regulations.
A generic name for one particular compound of the same chemical family;
e.g. 2,3,7,8, tetrachlorodibenzo-p-dioxin is one congener of the 75
chlorinated dibenzo-p-dioxin congeners.
Daily performance checks
A routine testing of the electronic lab equipment to confirm that the
machines are properly calibrated and accurate. These are
performed at routine times each day and are recorded as part of the
Quality Assurance/Quality Control (QA/QC) data for that equipment.
A calculated value, the level at which a particular piece of analytical
instrument can detect the presence of a specific compound above the
background noise of the instrument detector. For dioxin/furan
analysis, this value is determined by the signal to noise ratio which
must be a minimum of 2.5.
Dry standard cubic feet (dscf)
See dry standard cubic meters. The only difference between the
two terms is the use of English units of measure rather than metric.
Dry standard cubic meters (dscm)
Concentration of contaminants in gases emitted from sources (such as
cement kilns) are generally expressed as a weight of that material per
a volume of gas. Emissions from sources often contain water vapor
from evaporation of water in the processed material or as water from
combustion of hydrocarbons. This amount varies from source to
source and at variable temperatures from source to source. To
make an emission rate meaningful for comparison to another source or to
a permit limit, the emission rate must be stated as a weight per (dry)
gas at standard conditions. The specific standard conditions are
set by the applicable authority, often a national laboratory group.
Duplicate analyses The sample is split and then each split is subjected to analysis.
Filter support A housing that holds the flimsy glass fiber filter in place in the sampling train.
The second main step in the analysis of a dioxin/furan field
sample. After the field sample has gone through extraction
procedures, the dioxin/furans, if there are any, are put into a
solution. The solution must be cleaned up and
fractionated. This step is a series of procedures where the
solution is passed through different columns of packed chemical
material to purify the solution prior to injecting it into the
Gas chromatograph/mass spectrometer (GC/MS)
A gas chromatograph is an instrument where the sample gas passes
through a carefully heated coiled metal, glass or silica tubing packed
with a specially prepared media, or a glass or silica coil of a very
precise bore measurement with an internal coating which causes the
different compounds in the gas to separate based on their transport
properties. Each compound exits the coil in a known sequence and
at a predictable time. This permits identification of the
compounds in the sample through the use of some type of detector at the
exit of the coil. The
mass spectrometer is the detector that measures each of these compounds
as they leave the coil. This is the most accurate device for
identifying and determining the concentration of different organic
Glass fiber filter
A special type of filter used in the Method 23 stack sampling
train. It will not react to chlorinated hydrocarbons as some
other mineral fiber or paper filter may.
High resolution gas chromatography (HRGC)
A gas chromatograph especially configured to detect very low
concentrations of hydrocarbon. The HRGC must be equipped with
temperature programming, a high resolution capillary column for the
separation, as well as other required accessories such as syringes,
high purity gases and a data system to control operations, collect and
process data. For dioxin/furan analysis of samples.
High resolution mass spectrometry (HRMS)
A mass spectrometer which can identify a hydrocarbon by its very
specific ion mass. The unit must be able to resolve each ion mass
peak from another with a minimum of 10% difference between each mass
peak. It also must have a data system to control and monitor the
multiple ion monitoring process. The data system must also be
able to acquire data at a minimum of ten ions in a single scan and be
able to provide other details of the mass spectra for each
hydrocarbon. For dioxin/furan analysis, the HRMS must be closely
coupled with a HRGC to separate the individual hydrocarbons (dioxin or
furan) before they enter the HRMS.
All of the dioxins (or furans) of the same base grouping designated by
the number of chlorine molecules in the compound. For example,
all tetrachlorodibenzo-p-dioxins (TCDD) have four chlorine molecules
and are a homologous group. 2,3,7,8-TCDD has four chlorine
molecules, one each at the 2, 3, 7 and 8 positions, and is thus one
member of the tetra group.
A glass tube containing a fluid that is part of a sample train.
Gas from the source is passed through a dip leg (bend in the tubing)
and then bubbles up through this fluid. The fluid may be water or
a chemical that reacts with some constituent in the gas. The gas
analytes of interest then remain in the fluid for subsequent analysis.
Initial instrument calibration
The first calibration of an instrument, usually intended to achieve a
gross, or rough, calibration that will be subsequently refined for
Any substance or mechanism that compromises the accuracy of an analysis
of another substance. Sample preparations and analyses must often
be performed in certain steps to remove substances that would reduce
the accuracy in determining the concentration of another substance.
These are standards which are added to the sample to be analyzed prior
to it being analyzed. For dioxin/furan analysis, they may be the
same compounds as the analytes of interest, very similar or
radioactively labeled. They are added to the sample in a
quantitatively known manner. They are then analyzed for, just as
are the analytes of interest. Results allow the analyst to be
more precise in determining the concentration of the unknown
analytes. Also, the results can indicate whether any portion of
the sample was lost during the many steps of the analysis, therefore
effecting the accuracy of the results.
A term which pertains to the sampling of stack gas. It means
taking the sample under specific and relatively constant physical
conditions such as gas flow rates, velocity, pressures, etc. The
sampling of a stack requires several hours, movement of the sampling
train between sample points on the stack and obtaining the required
amount of gas sample. In order to extract a truly representative
sample from a stack the sample must be withdrawn within 10% of
isokinetic conditions. The sample probe nozzle is a key in
achieving these monitored conditions. It should be selected and
pre-tested to ensure its ability to maintain the isokinetic conditions
while sampling gases moving through the stack.
In this case, one specific arrangement of chlorine molecules in a
homologous group, e.g. 2,3,7,8-TCDD is one isomer of the TCDD
group. 2,4,7,8-TCDD would be another isomer of the same group.
Kg Kilogram, or 1000 grams.
A quality control sample prepared and run during the analysis of the
sample. It is prepared using the same media and chemical the
field sample was taken in. It is split into two samples and
spiked with internal standards. The two samples are then analyzed
through the same steps as the field sample. The results are
compared and for dioxin/furan testing should agree within 20% of each
mg Milligrams, or 0.001 grams.
ng Nanogram, or 0.000000001 grams.
ng/dscm Nanograms per dry standard cubic meter. See dry standard cubic meter.
The tip of the sample probe inserted into the stack to sample the stack
gas. These nozzles come in a number of opening sizes
corresponding to the flow rate needed for the sampling period.
The metal or glass coil that has the precisely ground specially
prepared media in it that the gas chromatograph carrier gas flows
through. The sample when injected into the carrier gas, flows
through the media which separates compounds in the sample. See
also gas chromatograph/mass spectrometer (GC/MS).
Products of Incomplete Combustion (PICs)
Hazardous organic compound emissions which, in theory, result in
complete combustion of fuels or other materials. Burning
hydrocarbons breaks them down from more complex into more simple
compounds. Burning that is not hot enough or long enough will
result in some intermediately complex hydrocarbons. These
intermediately complex hydrocarbons also routinely occur in nature for
a wide variety of reasons. The EPA assumes that hydrocarbons
volatized out of the raw feed in a cement kiln (or lime kiln, or
aggregate kiln) comes only from incomplete combustion.
Quality Assurance/Quality Control (QA/QC)
A set of procedures to ensure that analyses have been performed
accurately. Some of these procedures precede the analysis and
some follow the analysis.
A limit above the detection limit which, through calculation, meets
certain statistical confidence criteria as defined by the test method,
e.g. the confidence level for dioxin/furan analysis is 99%. The
lowest possible level is also called the minimum quantitation limit
response factor This is a value calculated for each analyte of
interest from calibration response factor data. These values are
then used to determine the concentration of those analytes in the
analysis of the test sample. This determination is made by
comparing the responses of the known analytes to the responses of the
Resin absorbent sampling cartridge This is a glass vial with a specially prepared resin that adsorbs organics out of the sample gas.
Response factor data
This data is obtained during analytical instrument calibration
procedures. In dioxin/furan testing, the data comes from
analyzing a series of standards with the GC/MS and recording the
detector response to the known concentration of the individual analytes
in each standard. Calculations are then made using the detector
response data and the known concentration of each analyte in the
standard to determine the relative response factor.
A solution used to wash across the inner surface of sampling equipment
to ensure that all of the sample being analyzed will have all of the
Sample catch The actual amount of sample that the sampling equipment contains at the end of the sampling period.
The type of media (broadly; solid, liquid, or gas) that the analytes
are found in, sampled in, or extracted to. For example, a stack
gas may be sampled in the gas phase by a bag or passed on to a sample
train and captured in solid or liquid media. Within each of the
broad categories there can be many more types of media or matrix.
In dioxin/furan testing, quality control samples using the sample
matrix must be tested to determine if they have an effect on the
Sample probe The tubing (generally glass) that is inserted into the gas stream to extract a sample of the stream.
Sample recovery operations
The activity to properly transfer the sample out of the sampling device
into containers. This includes measurement of the fluids, rinsing
and measurement of the rinsate, the addition of preservatives or
Sample train breakdown
The first steps in sample recovery. It involves very careful
disassembly, rinsing and collection of sampling apparatus components
and materials. For dioxin/furan testing, specific procedural
steps are specified by the test method for all of these activities.
Sample transfer lines The tubing connecting different filters, impingers, etc. in a sample train through which the sample gas flows.
Greases used to create gas-tight connections between glass to glass
connections or Teflon to glass connections. The test method for
dioxin/furan emissions requires that no greases be used to prevent
contamination of the sample.
Spike The addition of a compound of known composition and concentration to a material prior to analysis.
Standard See internal standards.
A substituted compound. When a compound is very hazardous or
difficult to work with, it may be desirable to use a less hazardous
material which has similar properties. A surrogate compound
should be approved before it is used. In dioxin/furan testing a
group of surrogate compounds are used as a part of the internal
standards. The method specifies when and where these should be
Toluene QA rinse
A quality control sample collected when testing stack gases for
dioxin/furan emissions using method 23. After the stack sampling
equipment has been cleaned and rinsed with acetone and methylene
chloride as per the method, a final rinse is made with toluene.
This rinse may be kept separate from the other cleaning rinses.
If it is analyzed separately for dioxin/furan it can demonstrate that
the prior cleaning and rinsing were effective in removing all the
dioxin/furan from the sampling equipment. This rinse may be added
to the other rinses and become part of that analysis.
Toxic Equivalent Quantity (TEQ)
The quantity of each PCDD/PCDF emitted multiplied by its TEF. In
this manner, devices that emit different relative quantities of the
different PCDD/PCDF compounds can be compared to a standard limit.
Toxicity Equivalency Factor (TEF) An assignment of relative toxicity with 2,3,7,8-TCDD being "1".
μg Micrograms, or 0.000001 grams.