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4 Test method
4.
Some test procedures specified by the test method may lead to dangerous situations
4.
Unless otherwise specified, only reagents confirmed to be analytically pure and grade 3 water specified in GB/T6682-1992 are used in the analysis
4.
Take an appropriate amount of laboratory samples in the colorimetric tube, test and observe whether the samples have suspended solids and mechanical impurities
4.
Carry out according to the method specified in GB/T21541-2008
4.
4.
Carry out according to the method specified in GB/T6283-1986
Take the arithmetic average of the two parallel determination results as the determination result, and the absolute difference between the two parallel determination results shall not be greater than 10% of the average of the two parallel determination results
4.
4.
The water in the laboratory sample undergoes a quantitative reaction with the iodine in the electrolyte in the presence of organic alkali and methanol .
I 2 +SO 2 +H 2 O→2HI+SO 3
2I -- 2e→I 2
The number of iodine molecules participating in the reaction is equal to the number of water molecules, and the iodine produced by electrolysis is proportional to the amount of electricity consumed
4.
5.
2.
2 Instruments
4.
5.
2.
2.
1 coulomb moisture meter: H sensitivity 0.
1 ug 2 O
.
Or other trace moisture analyzers that can meet the analysis requirements can also be used;
4.
5.
2.
2.
2 Balance: the division value is 0.
01g;
4.
5.
2.
2.
3 Syringe: 5mL
.
4.
5.
2.
3 Reagents
Electrolyte (commercially available reagent) used in conjunction with the Coulometric Moisture Analyzer
.
4.
5.
2.
4 Analysis steps
Add electrolyte to the electrolytic cell of the coulomb power and moisture meter, and adjust the coulomb power and moisture meter to make the titration cell reach an equilibrium state
.
Use a syringe to draw about 2mL laboratory sample (or adjust according to the water content in the laboratory sample), weigh it to the nearest 0.
01g, add it to the coulometric moisture analyzer, and immediately perform the coulometric titration.
After the titration is completed: according to the sample Calculate the water content or read the water mass fraction directly on the Coulomb Moisture Analyzer
.
Take the arithmetic average of the two parallel determination results as the determination result, and the absolute difference between the two parallel determination results shall not be greater than 0.
0008% of the average of the two parallel determination results
.
4.
6 Determination of acidity
4.
6.
1 Method summary
The acid contained in the sample was extracted with water, and the phenol green ethanol solution in bromine was used as the indicator solution and titrated with sodium hydroxide standard titration solution
.
4.
6.
2 Apparatus
4.
6.
2.
1 Micro burette: 0.
02mL sub-scale;
4.
6.
2.
2 Balance: the maximum weighing is not less than 2000g, and the graduation value is 0.
1g
.
4.
6.
3 Reagents
4.
6.
3.
1 Sodium hydroxide standard titration solution: c(NaOH)=0.
01mol/L;
4.
6.
3.
2 Bromocresol green ethanol solution: 1g/L;
4.
6.
3.
3 Water: The bromocresol green ethanol solution is neutral
.