Urea is converted to biuret in the range 132 to 135°C (depending on purity) associated with loss in weight. Measuring the loss in weight of unknown samples and comparing with a standard urea, the amount of Urea present in the unknown samples can be estimated.
The amount of urea present is also often calculated on the basis of the total loss on heating up to 430 º C when urea decomposes.
However, in the present work, the estimation of Urea content has been carried out based on the conversion of Urea to Biuret and Weight loss Vs Temperature was measured by DSC/TGA by observation of characteristic peak at 134º C (approx).
Apparatus used: STA 6000 ( Perkin Elmer )
|Sample No||LOI at 240 º C ( Approx )|
|CRM Urea||61.002 %|
|Unknown urea 1||58.058 %|
|Unknown urea 2||59.828 %|
|Urea contents in CRM urea is 100 %.|
Accuracy of Results:
|Sample No||% of Urea by TGA||% of Urea by chemical Method.||Error %|
UNKNOWN UREA 1
UNKNOWN UREA 2
The analysis of urea by DSC /TGA is a specific method established through the above work. It is also less time consuming and accurate as evidenced by comparison with Chemical method and moreover less expensive.