With respect to transactions the following segregation of duties could be applicable:
This function should be segregated such that different managers are given positions of authority depending on position in the organization, remuneration, qualification etc.
ii. Execution of Duties
This limits authority i.e. a person who authorizes a given transaction can not execute it that is carry it out.
iii. Custody of resultant assets
An official organizing a given expenditure shouldn‘t keep on asset arising from such an expenditure.
This should be done by a person with sufficient knowledge and expertise and who is accorded powers to record transactions.