How can I effectively remove the lingering cat pee smell from my mattress that I just can't seem to get rid of?

To effectively remove the lingering cat pee smell from your mattress, you can try using a mixture of white vinegar and water to clean the affected area. After applying the solution, let it sit for a few hours before blotting it dry with a clean cloth. You can also sprinkle baking soda on the mattress and let it sit for a few hours before vacuuming it up. Additionally, using an enzyme-based cleaner specifically designed for pet odors may help eliminate the smell.