This standard specifies the spectrophotometric method for the determination of ozone in ambient air using sodium indigo disulfonate. When the volume is 5 to 30 L, this standard is applicable to the determination of ozone concentration in the air within the range of 0.030 to 1.200 mg/m3. GB/T 15437-1995 Determination of ozone in ambient air using sodium indigo disulfonate spectrophotometric method GB/T15437-1995 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of ozone in ambient air
Sodium indigo disulphonate spectrophotometrybzxz.net
Ambient air-Determination of ozone-Indigo disulphonate spectrophotometry 1 Subject content and scope of application
1.1 Subject content
This standard specifies the sodium indigo disulphonate spectrophotometry for the determination of ozone in ambient air. 1.2 Scope of application
1.2.1 Determination range
GB/T 154371995
When the sampling area is 5~301., this standard is applicable to the determination of ozone in the air in the concentration range of 0.030~1.200mg/m3. 1.2.2 Interference
Nitrogen dioxide has a positive interference on the determination of ozone, which is about 6 of its mass concentration. When the concentration of sulfur dioxide, hydrogen sulfide, peroxyacetyl nitrate (PAN) and hydrogen fluoride in the air is higher than 750, 110, 1800 and 2.5 μg/m\, it will interfere with the determination of ozone.
The presence of chlorine and chlorine dioxide in the air will make the determination result of ozone higher. However, in general, the concentration of these gases is very low and will not cause significant errors.
2 Principle
Ozone in the air reacts with the blue sodium disulfonate in the absorption liquid in an equimolar manner in the presence of a phosphate buffer, and fades to form sodium disulfonate. The absorbance is measured at 610 nmr. 3 Reagents
Unless otherwise specified, analytical reagents and double distilled water or water of equivalent purity that meet national standards are used during analysis. 3.1 Potassium bromate standard stock solution (1/6KBrO) = 0.1000mol/L Weigh 1.3918g potassium bromate (superior purity, 180C drying for 2h) and dissolve in water. Transfer to a 500mL volumetric flask and dilute to the mark with water. 3.2 Potassium bromate-potassium thiosulfate standard solution: (1/6KBrO) - 0.01000mol/L. Pipette 10.00mL potassium bromate standard stock solution (3.1) into a 10UmL volumetric flask and add 1.5% potassium bromide (KBr). Dilute to the mark with water. 3.3 Sodium thiosulfate standard stock solution: (Na,S,O,) = 0.1000ml/l. 3.4 Sodium thiosulfate standard working solution: (Na,S.O,) - 0.005000mol/l. Before use, dilute the sodium thiosulfate standard stock solution (3.3) with
3.5 sulfuric acid solution; 1+6 (V/V)
3.6 starch indicator solution: 2.0g/L. Weigh 0.20g soluble starch. Add a small amount of water to make a paste, slowly pour into 10>ml boiling water, and boil until the liquid is clear.
Approved by the State Environmental Protection Agency on March 25, 1995, and implemented on August 1, 1995
GB/T15437-1995
3.7 Phosphate buffer solution: (KH2PO4) = 0.050 mol/l, weigh 6.8 g potassium dihydrogen phosphate (KH2PO4) and 7.1 g anhydrous sodium hydrogen phosphate (Na2PO4) and dissolve in water to 1 000 mL. 3.8 Sodium indigo disulfonate (CINas). Abbreviated as ID, analytical grade and chemical grade. 3.9 IDS standard stock solution: weigh 25 g sodium indigo disulfonate (IDS), dissolve in water, transfer to a 500 ml brown container, dilute with water to the mark, shake, and standardize after 24 hours. This solution can be stored in a dark place below 20°C for two weeks. Calibration method: Pipette 20.00mL IDS standard reserve (3.9) into a 250rm iodine bottle. Add 20.00ml potassium thiosulfate-potassium bromide standard solution (3.2), then add 50mL water, cover the bottle stopper, and place in a 16±1 water bath thermos bottle. When the solution temperature is balanced with the water temperature, add 5.0mL sulfuric acid solution (3.5), immediately cover the bottle stopper, mix, and start timing. Place in a 16+1℃ water bath in the dark for 35±1min, add 1.0mL potassium iodide (KI), immediately cover the bottle, and shake until completely dissolved. After placing in the dark for 5min, titrate with sodium thiosulfate standard working solution (3.4) until the reddish brown color turns light yellow, add 5mL sodium thiosulfate indicator (3.6), and continue titrating until the color fades to bright yellow. The volume difference of sodium thiosulfate standard solution used in two parallel titrations shall not exceed 0.10ⅢL. 1S solution is equivalent to the mass concentration of ozone C
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