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

9.0 CALCULATION
9.1 Normality of Thiosulfate Solution (Section 7.2.6)
The normality of this solution. N, is calculated as follows :
W x 10 3 x 0.1
N = -----------------
V x 35.67
Where :
V - Volume thiosulfate used, ml
W - Weight of potassium iodate, g
35.67 - Equivalent weight of potassium iodate
9.2 Concentration of Sulphite Solution
The amount of sulphur dioxide per milliliter in the standard solution, is calculated
as follows :
(V1-V2) x N x K
C = -----------------
V
Where :
C - SO2 concentration in µg/ml
V1 - Volume of thiosulfate for blank, ml
V2 - Volume of thiosulfate for sample, ml
N - Normality of thiosulfate
K - 32000 (Milliequivalent weight SO2/µg)
V - Volume of standard sulphite solution, ml
9.3 Conversion of Volume
Convert the volume of air sampled to the volume at the reference conditions of
25 o C and 760 mm :
P 298
Vr = V x ------ x ---------
760 t + 273
Where :
Vr - Volume of air at 25 o C and 760 mm Hg, litres
V - Volume of air sampled, litres
P - Barometric pressure, mm Hg
t - Temperature of air sampled, o C
9.4 Sulphur Dioxide Concentration at the Reference Conditions
When sulphite solutions are used to prepare calibration curves, compute the
concentration of sulphur dioxide, C, in micrograms per cubic metre, in the sample
as follows :
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