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Chemical Industry Standard of the People's Republic of China
HG/T2750—1996
Published on April 8, 1996
Implemented on January 1, 1997
Published by the Ministry of Chemical Industry of the People's Republic of ChinaWHG/T2750—1996
This standard is revised on the basis of ZBG57005—87 "Indigo". The original standard proposed index requirements for intermediate grade and printing and dyeing grade for indigo. In this revision, according to the actual situation of indigo products, it is not appropriate to give index requirements for printing and dyeing grade, so it is modified and cancelled. At the same time, the provisions on the dyeing fastness of indigo powder standard samples on cotton fabrics and Appendix A—Determination of chlorine bleaching fastness (supplement) are cancelled. Considering that granular indigo accounts for a considerable proportion of indigo production, this revision proposes requirements for granular indigo. This standard will replace ZBG57005—87 from the date of implementation. This standard is proposed by the Technical Supervision Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the technical jurisdiction of Shenyang Chemical Research Institute of the Ministry of Chemical Industry. This standard was drafted by Beijing Dye Factory. The main drafters of this standard are Tao Guoyang, Chi Feng, Zhang Jianjin and Liu Li. This standard was first issued in April 1987.
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Chemical Industry Standard of the People's Republic of China
HG/T2750-1996
Replaces ZBG57005-87
This standard specifies the requirements, sampling, test methods, inspection rules, and marking, packaging, transportation and storage requirements for indigo. This standard applies to powdered indigo or granular indigo made from aniline and monochloroacetic acid to make potassium salt of anilinoacetic acid, and then alkali fused and oxidized. This product is mainly used for dyeing cotton fibers, and can be made into indigo white, bromine indigo, food dyes, biochemical agents, etc. Structural formula:
Molecular formula: C16H1002N2
Relative molecular mass: 262.27 (according to the 1991 international relative atomic mass) 2 Reference standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and the parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T601-88 Preparation of standard solution for titration analysis (volumetric analysis) of chemical reagents GB/T2383-80 Determination of sieve fineness of dyes GB/T2386-80
Determination of moisture content in dyes and dye intermediates 3 Requirements
The quality of indigo shall comply with the requirements of Table 1:
Table 1 Quality requirements for indigo
Content, %
Moisture, %
Fineness, amount passing 250μm (60 mesh) sieve, % Note: The fineness of granular indigo is exempt from inspection.
Approved by the Ministry of Chemical Industry of the People's Republic of China on April 8, 1996>
Dark blue uniform powder
Dark blue uniform granules
Implemented on January 1, 1997
W.bzsoso:com4 Sampling
HG/T2750—1996
4.1 Random sampling is carried out in batches (a batch is a uniform product mixed once). The total number of samples shall not be less than √N/2, and the number of samples for small batches shall not be less than 3 barrels. When sampling, be careful not to let impurities fall into the product. When sampling, use a sampler to explore the upper, middle and lower parts of the sample. The sampling volume shall not be less than 200g. After carefully mixing the sampled products, put them in two clean and dry ground-mouth bottles, seal them with paraffin, and label them, indicating: manufacturer name, product name, batch and sampling date, one bottle for inspection, and one bottle for storage for future reference. 5 Test method
5.1 Determination of appearance
The visual method is used for determination.
5.2 Determination of indigo content
5.2.1 Principle of the method
Based on the fact that indigo is oxidized to indigo red by potassium permanganate, causing the color change of the solution. 0
5.2.2 Instruments and reagents
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Erlenmeyer flask: 50mL, 1000mL,
Volume flask: 500mL,
Pipette: 25mL;
Acid burette: 25mL,
Sulfuric acid;
Standard potassium permanganate titration solution: c (1/5KMnO) = 0.02mol/L, prepared and calibrated according to the relevant provisions of GB/T601. 5.2.3 Determination steps
Weigh 0.5g (accurate to 0.0002g) of indigo in a 50mL conical flask, add 20mL of sulfuric acid, stir evenly with a glass rod, then place the conical flask in a water bath and react at 80-90℃ for 1.5h. After the reaction is completed, cool the solution and transfer it to a 500mL volumetric flask pre-added with 100-150mL of distilled water. Wash the conical flask with distilled water several times, add the washing liquid to the volumetric flask, cool to room temperature, dilute with distilled water to the scale and shake well. Accurately draw 25mL of this solution and place it in a 1000mL conical flask, add 500mL of distilled water, and then titrate with 0.02mol/L potassium permanganate standard titration solution. The flask must be shaken frequently during titration. During titration, the solution changes from blue to purple, then to green. When the green light turns yellow, the end point is reached. 5.2.4 Expression and calculation of results
The mass percentage of indigo content is represented by X and calculated according to formula (1): 0.00150XcXVX1 000
Wherein: 0.00150—
The mass of indigo equivalent to 1.00mL potassium permanganate standard titration solution [c(1/5KMnO,)=1.000mol/L] in grams;
The concentration of potassium permanganate standard titration solution, mol/L, V
—The volume of potassium permanganate standard titration solution consumed, mL,—The mass of the sample, g.
W.bzsoso:comHG/T2750—1996
The difference between the results of two parallel analyses should not be greater than 0.5%, and the arithmetic mean of the parallel determination results shall be taken as the determination result. 5.4 Determination of moisture content
It shall be carried out in accordance with the provisions of Chapter 2 of GB/T2386. 5.5 Determination of fineness
It shall be carried out in accordance with the provisions of GB/T2383.
6 Inspection rules
6.1 Inspection classificationwww.bzxz.net
All items specified in Table 1 are factory inspection items. 6.2 Factory inspection
Indigo shall be inspected by the quality inspection department of the manufacturer in accordance with the requirements of this standard. The manufacturer shall ensure that all indigo shipped out of the factory meets the requirements of this standard. Each batch of indigo shipped out of the factory shall be accompanied by a quality certificate in a certain format. 6.3 Re-inspection
If one of the indicators in the inspection results does not meet the requirements of this standard, samples shall be taken from twice the amount of packaging for re-inspection. If even only one item of the re-inspection results does not meet the requirements of this standard, the entire batch of indigo cannot be accepted. 6.4 User Acceptance
The user has the right to inspect the received indigo products in accordance with the provisions of this standard to check whether they meet the requirements of this standard.
7 Marking, packaging, transportation and storage
7.1 Marking
The outer packaging of indigo should be firmly marked with: manufacturer name, product name, registered trademark, standard number, product batch number, gross weight and net weight. A quality certificate should be attached to each package. The content includes: name, specification, batch number and production date. 7.2 Packaging
Indigo is packaged in iron drums or cardboard drums lined with plastic bags. The net weight of each package is 25kg. Other packaging can be determined by negotiation between the manufacturer and the user.
7.3 Transportation
During transportation, it should be protected from exposure to sunlight, moisture and collision. 7.4 Storage
The product should be stored in a cool, dry and ventilated warehouse. 3
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