Industrial Melamine (4)

5.

5.

Place the sample in a drying oven to dry, and weigh the reduction to measure the moisture content

5.

a) Flat-bottom weighing bottle 50mm×30mm;

b) Constant temperature drying oven

5.

a) Put about 5g of the sample into a pre-dried flat-bottomed weighing bottle of known mass, try to spread the sample to a uniform thickness, cover the bottle cap, and weigh to the nearest 0.

b) Open the lid, and place the weighing bottle and lid in a drying oven whose temperature is adjusted to (105±1)℃ to dry for 2 hours;

c) After cooling the weighing bottle and lid to room temperature in a glass desiccator, weigh it and calculate the reduction

5.

The mass percentage of moisture X _{2 is} calculated according to formula (3):

In the formula: m ₁ -the mass of the crucible with water, g;

m ₂ —the mass of the crucible, g;

m—the mass of the sample, g

Take the arithmetic mean of the two parallel determination results as the determination result

5.

5.

Add water to the sample, boil it and then quench it, and measure the pH of the supernatant liquid

5.

Glass electrode pH meter: The accuracy is 0.
1pH unit
.

5.
6.
3 Analysis steps

a) Weigh 5.
0g of the sample and place it in a 200mL tall beaker, add 100mL of pre-boiled water (pH6.
5～7.
0) to remove carbon dioxide and boil for 5min;

b) To avoid the influence of carbon dioxide in the air : quench to 20°C within 10 minutes, and immediately measure the pH of the supernatant liquid
.

5.
7 Ash determination

5.
7.
1 Method summary

Place the sample in a high-temperature furnace for high-temperature ashing, weigh out its residual amount, and then measure the ash content
.

5.
7.
2 Apparatus and equipment

a) Platinum, porcelain crucible or quartz crucible;

b) High temperature furnace
.

5.
7.
3 Analysis steps

a) Weigh more than 10g sample (the sampling amount varies with the ash content), accurate to 0.
02g, and place it in a pre-dried crucible with a known mass;

b) First heat it on an electric hot plate adjusted to 400～500℃ to make most of the samples volatilize and carbonize;

c) Then, put it into a high-temperature furnace adjusted to (750±50)℃ for ashing, and take it out after 1h;

d) Take out the crucible and place it in a glass desiccator, after cooling to room temperature, weigh out its residual amount, accurate to 0.
0002g, and obtain the ash content
.

5.
7.
4 Calculation of analysis results

The mass percentage of ash X _{3 is} calculated according to formula (4):

In the formula: m ₁ -the mass of ash added to the crucible, g;

m ₂ ——the mass of the crucible, g,

m—the mass of the sample, g
.

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.
01%
.

Related Links: Industrial Melamine (3)