You Do Need power plug adapter while traveling from American Samoa to Brazil.

Here is Why You Need An Adapter

The outlet and plug type used in Brazil are C and N and in American Samoa are A, B, F and I. This is how they look like.

American Samoa

In American Samoa, outlets of type A, B, F and I are in use.

Type A

Type B

Type F

Type I

Brazil

In Brazil, outlets of type C and N are in use.

Type C

Type N