MODEL RELEASED. Litmus test for amine solution. This piece of litmus paper has been turned blue by being dipped in a solution of an amine, indicating that the solution is alkaline. An amine is an organic nitrogen-containing chemical. Amines form alkaline solutions in water. Litmus paper, which uses a plant-based dye, is an acid-base indicator. It turns blue in alkaline solutions, and red in acidic solutions.