Ammonia

Question 1

Ammonia methods

Answer 1

Indirect vs direct.
Indirect:
1. Ammonia isolated eg by addition of alkali/cation exchange resin
2. Measured colourimetrically
a) nesslerization
b) Berthelot reaction

Direct:
1. Enzymatic (see equations)

Question 2

Pre-analytical considerations for ammonia

Answer 2

Plasma EDTA or heparin (Joondalup Li hep)
Fill tube completely
On ice
Separation required
Test heparin samples immediately after collection

Question 3

Interfering substances with ammonia

Answer 3

Haemolysis (RBCs contain 3x plasma concn of NH3)
Atmospheric contamination: cigarette smoking, lab reagents/ glassware containing ammonia