EUTHANASIA
Methods for euthanasia in primates are limited. Euthanasia is most commonly performed in primates with an overdose of a barbiturate. (Euthanasia agents should be stored in locked cabinets because they may be stolen or mistaken for other injectable drugs.)
Other methods are conditionally acceptable and are listed in the AVMA Guidelines on Euthanasia.
You should consult with the attending veterinarian for information on the method of euthanasia.
Regardless of the method of euthanasia - death must always be verified by the complete absence of a heartbeat.