NITRAZINE YELLOW
Nitrazine (Phenaphthazine ) paper is used to measure the vaginal pH of expectant mothers. Nitrazine paper is impregnated with an indicator dye Phenaphthazine. The color changes as pH changes, giving a broad range of colors from yellow through blue.
Nitrazine Yellow is used to test vaginal pH during late pregnancy to determine the breakage of the amniotic sac. To perform a fecal pH test for diagnosing intestinal infections or other digestive problems.
The effect of infection on the test has been examined. A negative result is of use in excluding the diagnosis of ruptured membranes.
Throat swabs impregnated with nitrazine yellow have been used to detect pH change in the vagina before and after amniotomy.