Industrial Thiourea (3)

4.

4.

4.

4.

4.

4.

Weigh about 100 g of thiourea, place it in a 500 mL beaker, add 300 mL of water, heat to dissolve, filter, and rapidly cool to precipitate crystals, filter with glass sand crucible, and wash with 100 mL of ethanol twice

4.

4.

4.

Pipette 2mL, 5mL, and 10mL of thiocyanate impurity standard solution into a 50mL colorimetric tube, add 1.

4.

Weigh about 1.

4.

Execute according to GB/T617

4.

The sample size is about 5g, the burning temperature is (850±25)℃, and the burning time is 0.
5h
.
Others shall be carried out in accordance with the provisions of GB/T7531
.

Take the arithmetic mean of the two parallel determination results as the determination result
.
The difference between the two parallel determination results shall not exceed 0.
02%
.

5 Inspection rules

5.
1 All items specified in this standard are type inspection items, among which thiourea content, heating loss, water-insoluble content, melting point, and ash are classified as ex-factory inspection items
.
Under normal circumstances, type inspection shall be carried out at least once a month
.

5.
2 Industrial thiourea should be inspected by the quality inspection department of the manufacturer
.
The manufacturer shall ensure that all manufactured products meet the requirements of this standard
.

Each batch of products should be accompanied by a quality certificate in a certain format, which includes the product name, product grade, manufacturer name, factory address, batch number or production date and the number of this standard
.

5.
3 The production volume of industrial thiourea is one batch per shift
.

5.
4 Determine the number of sampling units according to 6.
6 of GB/T6678-1986, and the sampling technique should meet the requirements of GB/T6679
.
After mixing the sampled product, divide it into about 200g according to the quarter method, and put them into two clean, dry jars with stoppers
.
Affix the label and indicate the product name, product grade, batch number, sampling date and the name of the sampler
.
One bottle is for inspection, and the other bottle is sealed and kept for two months for future reference
.

5.
5 The test result is judged according to the rounding value comparison method in GB/T1250
.
If one of the inspection results does not meet the requirements of this standard, samples shall be taken from twice the number of packaging units for re-inspection
.
Even if only one index does not meet the requirements of this standard as a result of the re-inspection, the whole batch of products is unqualified
.

6 Marking, packaging, transportation and storage

6.
1 Industrial thiourea is packed in plastic woven bags of Neicun polyethylene plastic bags
.
The net content of each bag is (25±0.
2)kg or packaged according to user requirements
.

6.
2 Industrial thiourea packaging containers should have firm and clear signs, including product name, trademark, manufacturer name, site, net content, batch number, number of this standard, and the "fear of rain" sign specified in GB/T191
.

6.
3 When transporting industrial thiourea, it should be protected from moisture
.

6.
4 Industrial thiourea is stored in a cool, dry and ventilated warehouse
.

Related links: Industrial Thiourea (2)