Ambient Air quality Monitoring Guidlines. - Maharashtra Pollution ...

(p) Repeat step (d) and (e) with another five SO2 concentration without
changing the span setting;
(q) Plot the SO2 analyser output values obtained in step (f) and (g) versus the
concentration used;
(r) Determine the calibration line of the analyser by means of a single linear
regression.
Note : Optionally, the procedure described above can be repeated if the
determinations of precision and accuracy are required.
7.2.3 Field Calibration Procedure with a Transfer Standard - A two-point calibration
of the analyser with a transfer standard calibrated previously against a reference
calibration system is acceptable in field conditions. In this case, follow the step
(b) to (e) of clause 7.2.2.
8.0 EXPRESSION OF RESULTS
Record the output signal for the air sample to be measured. Determine the
corresponding concentration by using the appropriate calibration function
obtained in clause 7.2.2.
Report the result, µg/m 3 or mg/m 3 , or the equivalent volume fractions ppb (v/v) or
ppm (v/v).
The equation to be used for converting ppm (v/v) into mg/m 3 is as follows :
C2 x 64 x 298 x P
C1 = 24.459 x T x 101.3
Where :
C1 = is the concentration of SO2, expressed in mg/m 3
C2 = is the concentration of SO2, expressed in ppm (v/v)
64 = is the molar mass of SO2, expressed in g/mol
298 = is the reference absolute temperature, expressed in K
P = is the measured gas pressure, expressed in hPa
24.459= is the volume of 1 mol, expressed in L, at 298 K and 1013 hPa
T = is the measured temperature, expressed in K
101.3 = is the reference gas pressure, expressed in hPa
9.0 REFERENCE
ISO 10498.2. Ambient Air - Determination of Sulphur Dioxide - Ultraviolet Fluoroscence
method.
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