Warning: This standard does not mention all the safety issues related to the use of the standard.
The user is responsible for taking appropriate safety and protective measures and ensuring compliance with the conditions stipulated by the relevant national laws and regulations
.
1 Scope
This standard specifies a general method for the direct determination of ignition residues of organic butane products
.
The wood standard applies to the determination of the burning residue content of organic chemical products
.
2 Normative references
The clauses in the following documents become the clauses of this part after being quoted in this part
.
For dated reference documents, all subsequent amendments (excluding errata content) or revisions do not apply to this section.
However, all parties who have reached an agreement based on this section are encouraged to study whether the latest versions of these documents can be used
.
For undated reference documents, the latest version is applicable to this section.
Preparation of preparations and products used in GB/T603-2002 chemical reagent test method (ISO6353-1; 1982, NEQ)
3 General rules
Unless otherwise specified, only reagents confirmed to be analytically pure are used in the analysis
.
The preparations and products used in the analysis are prepared in accordance with the provisions of GB/T603-2002 when other requirements are not specified
.
4 Method summary
The residual substance after carbonization and high-temperature burning of the sample is weighed with a balance to obtain the mass of the burning residue
.
5 Reagents
5.
1 Nitric acid
.
5.
2 Hydrochloric acid solution (20%)
.
6 Instruments
6.
1 Analytical balance: the division value is 0.
0001g
.
6.
2 High temperature furnace: The temperature can be controlled (500～100C) ℃, and the temperature control accuracy is (±25) ℃
.
6.
3 Crucible: Porcelain crucible, quartz crucible, platinum crucible, etc.
with a volume of (30-100) mL
.
6.
4 Desiccator: Install proper desiccant (such as color-changing silica gel, anhydrous calcium chloride, etc.
) inside
.
7 Analysis steps
7.
1 Treat the crucible with hydrochloric acid solution
.
The porcelain crucible is soaked for 24h or boiled for 0.
5h; the quartz crucible and platinum crucible are soaked for 2h, washed and dried
.
7.
2 Put the processed crucible into a high-temperature furnace, burn it for an appropriate time at the selected test temperature, take out the crucible, cool in the air (1～3) min, and then move it into a desiccator to cool to room temperature (about 45min) ), weigh to the nearest 0.
0002g
.
Repeat the operation to a constant weight, that is, the difference between the two weighing results is not more than 0.
3mg
.
7.
3 Weigh the specified amount of laboratory samples with a constant amount, and the weighing quality of each laboratory sample to be determined should be based on the amount of residue not less than 3 mg
.
When the sample amount is large, the method of weighing and adding samples at a time can be adopted until all the laboratory samples are carbonized or volatilized completely
.
7.
4 Place the crucible containing the sample on the electric furnace and slowly heat it until the sample is fully carbonized
.
Move the crucible into the high-temperature furnace and operate according to 6.
2
.
7.
5 For samples that are more difficult to burn, add (0.
5-1.
0) mL of nitric acid to the carbonized crucible to moisten the carbonized material, heat it on an electric furnace until the brown smoke disappears, and then move it into a high-temperature furnace and operate according to 6.
2
.
7.
6 In the same test: the same desiccator should be used, and the same number of crucibles should be placed in a constant amount each time
.
The cooling time of an empty crucible and a crucible with residue is the same
.
7.
7 The burning temperature should be selected from the following temperatures according to different products: 650℃, 750℃, 850℃
.
8 Result calculation
The mass fraction w of the burning residue, expressed in %, is calculated as follows:
Where:
m 1 -the value of the mass of crucible plus residue, in grams (g);
m 2 -the value of the mass of the crucible, in grams (g);
m—The value of the mass of the sample, in grams (g)
.
Take the arithmetic average of the two parallel determination results as the determination result
.
9 tolerance
When the mass fraction of the burning residue w≥20.
01%, the absolute difference between the two parallel determination results is not more than 10% of the arithmetic mean of the two determination values;
When the mass fraction of the burning residue w<0.
01%, the allowable difference of the two parallel determination results is specified in the product standard according to the index of the burning residue
.
