DETERMINATION OF TITRABLE ACIDITY AND AMMONIA CONTENT IN URINE

 

DETERMINATION OF TITRABLE ACIDITY

AND AMMONIA CONTENT IN URINE

 

 

Principal: The titrable acidity of urine is mainly due to acid phosphate and to a lesser extent due to weak organic acid. Titrable acidity can be determined by titrating urine with standard alkali with phenolphthalem indicator.

 

                NaH₂PO₄ + NaOH à NaHPO₄ + H₂O

 

                Since Calcium interferes during titration due to the precipitation as calcium phosphate. It is removed completely as calcium oxalate before estimation.

 

                Ammonia in urine arises from hydrolysis of glutamine (60%) and due to oxidative deamination (40%) in the Kidney.

 

                Ammonia is estimated by the formol titration method when neutral formaldhyde is added to solution. Containing ammonium salt’s H+ ions are librated which can be titrated with standard alkali. Hexamethylen tetramine is the other product in this reaction.

 

Procedure: A: Titration for titrable acidity

 

                Pipette 25ml urine into a 250 ml conical flask and add 2 spatula of potassium oxalate to precipitate calcium. Add 2 drops of phenolphthalein. Rotate the flask for 1-2 minutes and titrate against NaOH. Note the titer value (A ml) when a permanent pale pink colour appears preserve the contents for ammonia estimation.

 

                B: Titration for ammonia:

 

                Note initial reading of burette, Add 5 ml of neutralized formalin to the above flask, pink colour disappears as a result of liberation of H+. Titrate against NaOH until the pale pink colour appears. Record the titre value (Bml)repeat both titrations till concordant value are obtained.