Unfortunately this sodium salt slowly deteriorate with time. Solutions of the salt - such as liquid veterinary Nembutal - need to be watched for signs of this deterioration. Any precipitate forming in the liquid is cause for concern. Exit advises that if they have their Peaceful Pill barbiturate in the form of the dissolved salt that they consider having the solution assayed if there is any sign of deterioration (or if the expiry date on the bottle is significantly exceeded).
This is readily done by extracting a small quantity of the liquid from the sterile sealed bottle of veterinary Nembutal using a small (1ml) diabetic syringe. The seal on the bottle is not broken by this procedure and the small sample can assayed using the Exit Test Kit (Fig 13.5).
Extending the shelf life of Nembutal
If the solution of sodium pentobarbital one has obtained is not to be used for many years it is wise to consider conversion of the dissolved salt to the more stable crystalline form.
Veterinary Nembutal solutions of sodium pentobarbital are buffered solutions at an alkaline pH, usually stabilised with 10% alcohol and ethylene glycol. Reducing the pH by the addition of dilute hydrochloric acid (or vinegar) will force sodium salt to back into the insoluble crystalline form.