Nitrazine

Nitrazine

IUPAC name (3E)-3-[(2,4-Dinitrophenyl)hydrazono]-4-oxonaphthalene-2,7-disulfonic acid
Other names Nitrazine yellow; Phenaphthazine
Identifiers
CAS number	1716-22-9
PubChem	6911856
ChemSpider	5288340^Y
Jmol-3D images	Image 1
SMILES [O-][N+](=O)c1ccc(c([N+]([O-])=O)c1)N/N=C3/C(=C\c2c(ccc(c2)S(=O)(=O)O)C3=O)S(=O)(=O)O
InChI InChI=1S/C16H10N4O11S2/c21-16-11-3-2-10(32(26,27)28)5-8(11)6-14(33(29,30)31)15(16)18-17-12-4-1-9(19(22)23)7-13(12)20(24)25/h1-7,17H,(H,26,27,28)(H,29,30,31)/b18-15-^Y Key: IHRSXGONVFFQQF-SDXDJHTJSA-N^Y InChI=1/C16H10N4O11S2/c21-16-11-3-2-10(32(26,27)28)5-8(11)6-14(33(29,30)31)15(16)18-17-12-4-1-9(19(22)23)7-13(12)20(24)25/h1-7,17H,(H,26,27,28)(H,29,30,31)/b18-15- Key: IHRSXGONVFFQQF-SDXDJHTJBN
Properties
Molecular formula	C₁₆H₁₀N₄O₁₁S₂
Molar mass	498.40 g/mol
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Nitrazine or phenaphthazine is a pH indicator dye.

Nitrazine test

As the disodium salt, it is used in pH testing strips for medical applications. It is also used in civil engineering to determine the carbonation spread in concrete structures and therefore assess the state of the rebar's passivation film. More sensitive than litmus paper, nitrazine indicates pH in the range of 4.5 to 7.5.

The test is used to test vaginal pH during late pregnancy to determine the breakage of the amniotic sac.^[1] While vaginal pH is normally acidic, a pH above 7.0 can indicate that the amniotic sac has ruptured.^[2] (However, elevated pH can also be associated with bacterial vaginosis.)^[3]

Nitrazine papers can also be used to perform a fecal pH test to diagnose intestinal infections or other digestive problems.^[4]

They can also be used to test the pH of the human eye.^[5]

References

^ Erdemoglu E, Mungan T (July 2004). "Significance of detecting insulin-like growth factor binding protein-1 in cervicovaginal secretions: comparison with nitrazine test and amniotic fluid volume assessment". Acta Obstet Gynecol Scand 83 (7): 622–6. doi:10.1111/j.0001-6349.2004.00343.x. PMID 15225185.
^ "Nitrazine paper". http://www.pointofcare.net/procedures/NitrazineProcedure.htm.
^ Sobel JD, Nyirjesy P, Kessary H, Ferris DG (September 2009). "Use of the VS-sense swab in diagnosing vulvovaginitis". J Womens Health (Larchmt) 18 (9): 1467–70. doi:10.1089/jwh.2008.1305. PMID 19743911.
^ "Point-of-Care Testing, Fecal pH Measurement". http://cpmclabinfo.cpmc.columbia.edu/chapter/mono/pc000300.htm.
^ "NITRAZINE PAPER: DETERMINATION OF NORMAL OCULAR pH". http://pangloss.ucsfmedicalcenter.org/LabMan/poct/SpecialtyWaivedTests/Nitrazine.pdf.