• Formulating

  Stabilizing urea with gluconolactone

  Posted by JonahRay on August 13, 2024 at 11:00 am

  Hi guys!

  I read about stabilizing urea with gluconolactone. It was recommended to use it at a rate of 15% of urea. If I use 3% urea and try 0.45% gluconolactone it is much too acidic. If I reduce the amount of gluconolactone to bring it to around pH 5, the pH climbs at 45C stability test.

  I haven’t yet tried to use 0.45% gluconolactone and then neutralizing it to an acceptable pH with NaOH yet. Would that make any sense?

  Thanks!

  chemicalmatt replied 3 weeks, 2 days ago 4 Members · 3 Replies
• 3 Replies

• 

  MarkBroussard

  Member

  August 13, 2024 at 8:24 pm

  @JonahRay

  You might try monitoring it for a couple of weeks or so. Gluconolactone tends to cause an acidic pH drift over time.

• 

  PhilGeis

  Member

  August 14, 2024 at 3:12 am

  Gluconolactone hydrolyzes/breaks down spontaneously in solution to gluconic acid. Consider https://pubmed.ncbi.nlm.nih.gov/25043489/

  Are you determining urea levels in stability testing?

• 

  chemicalmatt

  Member

  August 20, 2024 at 1:02 pm

  What Phil & Mark said…plus there are simpler ways to stabilize urea. Most common is to employ a lactate/lactic acid buffer at pH5.5 or so. An uncommon one is to add rice starch to the formula. Some amyloid starches adsorb urea in solution retarding degradation into biuret and ammonia. Cool, huh!

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