Nitrazine

Overview
Nitrazine or Phenaphthazine papers are pH strips used in medicine.

Interpretation
More sensitive than litmus paper, Nitrazine indicates pH in the range of 4.5 to 7.5. The test is often used to test vaginal pH during late pregnancy to determine the breakage of the amniotic sac. While vaginal pH is normally acidic, a pH above 7.0 indicates that the amniotic sac has ruptured. Nitrazine papers can also be used to perform a fecal pH test to diagnose intestinal infections or other digestive problems. They can also be used to test the pH of the human eye.