Types of Acids in the body Fixed acids Acids that do not leave solution Sulfuric and phosphoric acid. Catabolism of amino acids nucleic acids, and phospholipids.Types of Acids in the Body ◼ Fixed Acids: ◼ Acids that do not leave solution. ◼ Sulfuric and phosphoric acid. ◼ Catabolism of amino acids, nucleic acids, and phospholipids