GB/T 37560-2019Flame retardant chemicals—Determination of melamine and cyanuric acid in melamine cyanurate (English PDF)

4.1 Method summary

Use water at 50°C to dissolve the residual cyanuric acid and melamine in the sample; cool and filter; take the filtrate; use liquid chromatography external standard method for quantitative analysis.

4.2 Reagents and materials

4.2.1 Methanol.

4.5.1 Drawing of the standard curve

Take melamine standard stock solution; use the mobile phase to dilute into standard solutions of which the mass concentrations are 0 µg/mL, 0.2 µg/mL, 0.4 µg/mL, 0.8 µg/mL, 1.0 µg/mL, 2.0 µg/mL, 5.0 µg/mL, 10.0 µg/mL, 20.0 µg/mL, and 50.0 µg/mL. Inject and detect the standard solutions sequentially; plot the peak area-mass concentration, to obtain a standard curve regression equation.

4.5.2 Processing and determination of samples

Weigh 1 g (accurate to 0.1 mg) of melamine cyanuric acid sample into a 100 mL beaker; add 50 mL of water; incubate in a constant-temperature shaking bath at 50°C for 10 min ~ 15 min; use medium-speed quantitative filter paper to filter when it is hot; use water at 50°C to rinse off the beaker and the funnel; collect the filtrate in a 100 mL volumetric flask; rinse and fix-volume to the scale.

This solution is the to-be-test solution A. Take a certain amount of the to-be-test solution A to perform measurement; record the chromatographic peak area; calculate the mass concentration according to the standard curve. Do a blank test at the same time.

4.6 Test data processing

The melamine content X1 (%) which is expressed in mass fraction is calculated according to Formula (1):

Where:

rho -- the mass concentration of melamine in the sample solution, in micrograms per milliliter (µg/mL);

rho 0 -- the mass concentration of melamine in the blank solution, in micrograms per milliliter (µg/mL); m -- sample mass, in grams (g). V -- sample volume, in milliliters (mL);

1 000 000 -- the value when gram (g) is converted to microgram (µg).

Take the arithmetic mean of the results of two parallel tests as the measurement result; the absolute difference between the results of the two parallel tests is not more than 0.03%.

5.4 Test conditions

5.4.1 Column: C18 reverse phase column, 250 mm × 4.6 mm × 5 µm; or other columns that can reach the test conditions.

5.4.2 Detection wavelength: 220 nm

5.4.3 Flow velocity: 1.0 mL/min

5.4.4 Injection volume: 20 µL […]

5.5 Test steps

5.5.1 Drawing of the standard curve

Take cyanuric acid standard stock solution; use the mobile phase to dilute into standard solutions of which the mass concentrations are 0 µg/mL, 2.0 µg/mL, 5.0 µg/mL, 10.0 µg/mL, 20.0 µg/mL, 40.0 µg/mL, 50.0 µg/mL, 60.0 µg/mL, 80.0 µg/mL, and 100.0 µg/mL. Inject and detect the standard solutions sequentially; plot the peak area-mass concentration, to obtain a standard curve regression equation.

5.5.2 Processing and determination of samples

Take a certain amount of the to-be-test solution A which is gained from 4.5.2 to perform measurement; record the chromatographic peak area; calculate the mass concentration according to the standard curve. Do a blank test at the same time.

5.6 Test data processing

The cyanuric acid content X2 (%) which is expressed in mass fraction is calculated according to Formula (2):

Where:

rho -- the mass concentration of cyanuric acid in the sample solution, in micrograms per milliliter (µg/mL);

rho 0 -- the mass concentration of cyanuric acid in the blank solution, in micrograms per milliliter (µg/mL); m -- sample mass, in grams (g). V -- sample volume, in milliliters (mL); […]