[darin]

Hi there,

If I have many lots of urea to test, how can I determine the %purity of urea and control the quality? Do you have any simple method to test?


Thank you so much

[Schrödinger]

Maybe you can use colligative properties like elevation in boiling point, depression is freezing point, etc.
It's just a random guess. Please correct me if I am wrong.

[marquis]

Two methods that might work are Kjeldahl and nir infrared (NIR).  Both usually track the nitrogen in the compount.  The NIR takes a moderate investment in instruments.  The kjeldahl is much less expensive, but takes a fair amount of time to perform.

[steven]

Hi,

Method of Assay
Accurately weigh about 0.5 g of the sample and dissolve in a 10% sulfuric acid solution and dilute to 100 ml with the same acid. Introduce 5.0 ml of this solution into a long-necked combustion flask, add 10 ml of sulfuric acid TS and heat gently until gas is no longer evolved. Boil gently for 10 min, cool and add cautiously 40 ml of water. Cool again and place in a steam-distillation apparatus. Add 50 ml of 10 N sodium hydroxide solution and distill immediately by passing steam through the mixture. Distil for 1 hour, collecting about 50 ml of distillate in 40 ml of a 4% w/v solution of boric acid. Add 0.25 ml of methyl red/methylene blue TS and titrate with 0.1 N hydrochloric acid. Carry out a blank determination. Each ml of 0.1 N hydrochloric acid is equivalent to 3.003 mg of CH4N2O.

Steven