Bromocresol purple

Bromocresol purple
Skeletal formula of bromocresol purple in cyclic form
Ball-and-stick model of the bromocresol purple molecule in cyclic form
Names
IUPAC name
4,4'-(1,1-Dioxido-3H-2,1-benzoxathiole-3,3-diyl)-bis(2-bromo-6-methylphenol)
Other names
5′,5″-Dibromo-o-cresolsulfonephthalein
Bromcresol purple
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.003.716
Properties
C21H16Br2O5S
Molar mass 540.22 g·mol−1
Appearance Purple powder
Melting point 241 to 242 °C (466 to 468 °F; 514 to 515 K) (decomposition)
< 0.1 %
Hazards
R-phrases (outdated) R36/37/38
S-phrases (outdated) S26, S36
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
0
1
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Bromocresol purple (BCP) or 5′,5″-dibromo-o-cresolsulfophthalein, is a dye of the triphenylmethane family (triarylmethane dyes) and a pH indicator. It is colored yellow below pH 5.2, and violet above pH 6.8. In its cyclic sulfonate ester form, it has a pKa value of 6.3, and is usually prepared as a 0.04% aqueous solution.[1]

Uses

A sample of bromocresol purple in its violet form
Bromocresol purple (pH indicator)
below pH 5.2 above pH 6.8
5.2 ⇌ 6.8

Bromocresol purple is used in medical laboratories to measure albumin. Use of BCP in this application may provide some advantage over older methods using bromocresol green.[2][3] In microbiology, it is used for staining dead cells based on their acidity, and for the isolation and assaying of lactic acid bacteria.[4][5]

In photographic processing, it can be used as an additive to acid stop baths to indicate that the bath has reached neutral pH and needs to be replaced.[6]

Bromocresol purple milk solids glucose agar is used as a medium used to distinguish dermatophytes from bacteria and other organisms in cases of ringworm fungus (T. verrucosum) infestation in cattle and other animals.[7][8]

pH Indicator

Similar to bromocresol green, the structure of bromocresol purple changes with pH. The low pH (acidic) form is yellow in solution and the high pH (basic) form is purple; the sultone (cyclic sulfonic ester) is the acidic form in the following equilibrium.

References

  1. ↑ "Bromocresol Purple". NCBI PubChem. National Center for Biotechnology Information.
  2. ↑ Bachmann, Lorin M.; Yu, Min; Boyd, James C.; Bruns, David E.; Miller, W. Greg (2017-03-01). "State of Harmonization of 24 Serum Albumin Measurement Procedures and Implications for Medical Decisions". Clinical Chemistry. 63 (3): 770–779. ISSN 0009-9147. PMID 28073902. doi:10.1373/clinchem.2016.262899.
  3. ↑ Ito, Shigenori; Yamamoto, Daisuke (2010-02-02). "Mechanism for the color change in bromocresol purple bound to human serum albumin". Clinica Chimica Acta. 411 (3): 294–295. doi:10.1016/j.cca.2009.11.019.
  4. ↑ Kurzweilová, H.; Sigler, K. (November 1993). "Fluorescent staining with bromocresol purple: a rapid method for determining yeast cell dead count developed as an assay of killer toxin activity.". Yeast. 9 (11): 1207–1211. PMID 7509098. doi:10.1002/yea.320091107.
  5. ↑ Lee, H.M.; Lee, Y. (June 2008). "A differential medium for lactic acid-producing bacteria in a mixed culture". Letters of Applied Microbiology. 46 (6): 676–681. PMID 18444977. doi:10.1111/j.1472-765X.2008.02371.x.
  6. ↑ Anchell, Steve (2016). The Darkroom Cookbook (4 ed.). Routledge. ISBN 9781317337607 – via Google Books.
  7. ↑ Kane, J.; Summerbell, R.; Sigler, L.; Krajden, S.; Land, G. (1997). Laboratory Handbook of Dermatophytes: A Clinical Guide and Laboratory Handbook of Dermatophytes and Other Filamentous Fungi from Skin, Hair, and Nails. Belmont, CA: Star Publishing Company. ISBN 9780898631579.
  8. ↑ Beneke, E. S.; Rogers, A. L. (1996). Medical Mycology and Human Mycoses (illustrated ed.). Belmont, CA: Star Publishing Company. pp. 85–90. ISBN 9780898631753.

See Also

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