GB/T 2441.6-2010Determination of urea - Part 6: Water insoluble matter content - Weight method (English PDF)

Foreword

GB/T 2441 "Determination of urea" is divided into nine sections.

--- Part 1. total nitrogen content;

--- Part 2. biuret content spectrophotometry;

--- Part 3. Moisture Karl Fischer method;

--- Part 4. iron content - Phenanthroline spectrophotometric method;

--- Part 5. alkalinity volumetric method;

--- Part 6. Water-insoluble content - Gravimetric method;

--- Part 7. particle size sieving;

--- Part 8. sulphate content Visible turbidimetric method;

--- Part 9. methylene diurea content spectrophotometry.

This section GB/T 2441 Part 6.

1 Scope

This section GB/T 2441 specifies the method for measuring the weight of water-insoluble content of industrial urea.

This section applies to the determination of urea water insoluble content from ammonia and carbon dioxide synthetically produced.

Principle 2 Glass filter crucible aqueous urea solution is filtered under reduced pressure, the residue is expressed as the amount of water insoluble.

3 Instrument

3.1 usually laboratory instruments;

3.2 Glass filter crucible, No. 4 (pore diameter of 4µm ~ 16µm), volume 30mL;

3.3 Ovens;

3.4 water bath.

Step 4 Analysis Do two parallel determination of sample.

Laboratory samples weighing about 50g (accurate to 0.05g), the sample was dissolved in 150mL ~ 200mL of water. The solution was placed in 90 °C The water bath for 30min, immediately with a constant weight of No. 4 glass filter crucible hot vacuum filtration, washed with hot water residue 3 to 5 times per Times with about 15mL, remove the filter, at 105 °C ~ 110 °C constant temperature drying oven to constant weight.

5 Expression analysis

Water-insoluble content w, mass fraction (%) expressed by the formula. Where.

Value m1 --- dried residue mass in grams (g);

Numerical m --- sample mass, expressed in grams (g).

Calculation results are shown to four decimal places, take the parallel determination results as the arithmetic mean of the measurement results.

6 Allows the difference

The absolute difference between the parallel determination results is not more than 0.0050%.