Whisk the flour, baking powder, baking soda and salt in a bowl. Set aside.

In a separate bowl whisk the buttermilk, grapefruit juice and eggs together.

Add the wet ingredients to the dry until moist and let stand 10 minutes.

Coat a griddle pan or large skillet with butter to medium heat.

Spoon ¼ cup batter per pancake and sprinkle frozen blueberries over each pancake.

Cook 3 minutes or until edges begin to bubble and bottom is browned.

Turn over and cook until done.