Nitrazine
Nitrazine or phenaphthazine is a pH indicator dye often used in medicine. More sensitive than litmus, nitrazine indicates pH in the range of 4.5 to 7.5. Nitrazine is usually used as the disodium salt.
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| Names | |
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| IUPAC name
(3E)-3-[(2,4-Dinitrophenyl)hydrazono]-4-oxonaphthalene-2,7-disulfonic acid | |
| Other names
Nitrazine yellow; Phenaphthazine | |
| Identifiers | |
3D model (JSmol) |
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| Properties | |
| C16H10N4O11S2 | |
| Molar mass | 498.40 g/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
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Use
| Nitrazine (pH indicator) | ||
| below pH 4.5 | above pH 7.5 | |
| 4.5 | ⇌ | 7.5 |
- This test is done to ascertain the nature of fluid in the vagina during pregnancy especially when premature rupture of membranes (PROM) is suspect, however it is not recommended as it poses risk to infant mortality, many countries, such as the UK, are banning the use of nitrazine for such purposes.
- This test involves putting a drop of fluid obtained from the vagina onto paper strips containing nitrazine dye. The strips change color depending on the pH of the fluid. The strips will turn blue if the pH is greater than 6.0. A blue strip means it's more likely the membranes have ruptured.
This test, however, can produce false positives. If blood gets in the sample or if there is an infection present, the pH of the vaginal fluid may be higher than normal. Semen also has a higher pH, so recent vaginal intercourse can produce a false reading.
- To perform a fecal pH test for diagnosing intestinal infections or other digestive problems[1]
- In civil engineering, to determine the carbonatation spread in concrete structures and therefore assess the state of the rebar's passivation film.
References
- "Point-of-Care Testing, Fecal pH Measurement". Archived from the original on 2007-07-03.
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