Deng potassium salt of L-p-hydroxyphenylglycine (3)

4.

4.

Use glacial acetic acid as solvent and crystal violet as indicator to titrate with perchloric acid standard titration solution.

4.

4.

4.

4.

4.

Weigh about 0.

At the same time of measurement, perform a blank test with the same amount of reagent solution without adding the sample according to the same procedure as the measurement

4.

The mass fraction w _{1 of the} content of L-p-hydroxyphenylglycine Deng potassium salt , the value is expressed in %, calculated according to formula (2):

Where:

V ₁ —The value of the volume of the perchloric acid standard titration solution (4.

V ₂ —Blank test consumes the value of the volume of perchloric acid standard titration solution (4.

c — The exact value of the concentration of perchloric acid standard titration solution, the unit is moles per liter (mol/L);

m—the value of the mass of the sample, in grams (g);

M—The value of the molar mass of L-p-hydroxyphenylglycine Deng potassium salt, in grams per mole (g/mol)

Take the arithmetic mean of the two parallel determination results as the determination result, and the absolute difference between the two parallel determination results shall not exceed 0.

4.

According to the provisions of GB/T613-1988
.
Weigh 3g～5g laboratory sample, accurate to 0.
0001g, dissolve it with 50mL (9+100) hydrochloric acid solution, transfer it quantitatively to a 100mL volumetric flask, and shake it well
.

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 exceed 0.
3°
.

4.
7 Determination of loss on drying

4.
7.
1 Method summary

Measure the emission of volatile matter in the sample at a temperature of (105±2)°C
.

4.
7.
2 Analysis steps

Weigh 3g～5g laboratory samples, accurate to 0.
0001g, and place them in a weighing bottle that has been dried at (105±2)°C to a constant mass, and spread into a layer less than 5mm
.
Dry for 1.
5h in a constant temperature drying oven at (105±2)℃, cover the bottle and place it in a desiccator to cool for 30min, and weigh
.

4.
7.
3 Result calculation

The mass fraction w _{2 of} loss on drying , the value is expressed in %, calculated according to formula (3):

Where:

m—The value of the mass of the sample before drying, in grams (g);

m ₁ —The value of the mass of the sample after drying, in grams (g)
.

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 exceed 0.
05%
.

4.
8 Determination of pH

According to the provisions of GB/T9724-1988
.
Weigh 5.
0g laboratory sample, accurate to 0.
01g, add 100mL carbon dioxide- free water, dissolve it, and place it for 10min for determination
.

Related Links: L-p-Hydroxyphenylglycine Deng Potassium Salt (2)