Thermo Scientific TVA2020 Instruction Manual page 188

Response Factors
Response Factors
C-2 TVA2020 Instruction Manual
2. Relative Response Factor
In some cases, a response factor may be expressed as a percent or a ratio
of a compound's response to that of the calibration gas. This type of
response factor is calculated by dividing the detector response by the
actual concentration of a compound of interest.
Relative Response
(Multiply by 100 to express as a percent)
Note that the relative response is the reciprocal of the response factor
multiplier. (i.e. 1/RR = RFM). As in our example above, if 100 ppm of
a compound of interest produces a response of 50 ppm, the relative
response would be 50 divided by 100 (0.50 or 50 %).
When using a relative response factor to correct a TVA2020 reading,
simply divide the analyzer measured response by the relative response
factor expressed as a decimal. As in the example given above, if a 50
ppm reading is achieved, divide 50 by 0.50 to get the actual
concentration (100 ppm).
Like any FID or PID, the TVA2020 will respond to many different
compounds, producing a survey reading of all detectable compounds
present. If a single compound is present, a response factor can be applied to
correct for the response of that compound. If a mixture of compounds is
present, the TVA2020 will respond to all components of the mixture, and
will not differentiate between them. In general, response factors are not
available for mixtures of compounds. However, if the composition of the
mixture is known, a response factor can be calculated by adding weighted
fractions of the response factors of the individual compounds. For instance,
if a 75 % Benzene, 25 % Toluene mixture is to be measured, multiply the
Benzene response factor by 0.75, the Toluene response factor by 0.25 and
add them together to achieve the "weighted" response factor.
The data from a survey analysis may be expressed in a number of different
forms:
1. Relative to the calibration gas
If the compound with which the TVA2020 was calibrated is an
acceptable standard, then results may be expressed in terms of that
compound. For example, an FID reading of 100 ppm could be
Measured Response

Factor
Actual Concentrat ion
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