BROMOPHENOL BLUE: CHARACTERISTICS, PREPARATION, USES, TOXICITY - BIOLOGY - 2025

The bromophenol blue is an organic chemical nature, due to the property of having low tack certain pH values is used for chemical substances holder. That is, it is useful as a pH indicator.

It is also classified as a triphenylmethane dye. Triphenylmethane compounds and their derivatives are commonly used as colorants in the food, pharmaceutical, textile, and printing industries, among others.

Structure of bromophenol blue. Colors that it adopts according to the pH. Source: Panoramix303 /Pxhere.com. Edited image

This pH indicator is yellow at pH ≤ 3 and purple-purple at pH ≥ 4.6. Therefore, the visual transition interval is between 3 and 4.6.

This substance is also known as tetrabromophenol blue, but its scientific name is 3,3,5,5 - tetrabromophenol sulfonphthalein; and its chemical formula, C ₁₉ H ₁₀ Br ₄ O ₅ S.

The bromophenol blue pH indicator has low toxicity on skin and mucosa, and it has also been proven that it is not mutagenic. It is currently used in protein separation techniques by the polyacrylamide gel electrophoresis method and in two-dimensional electrophoresis.

It is emerging as a good dye to be used in vivo in therapeutic surgeries to remove the vitreous and other crystalline structures of the eye in humans. This technique would facilitate the visualization of these structures during the operation, guaranteeing their correct extraction.

characteristics

Bromophenol Blue is a crystalline-looking powder that has a brownish-orange or red-purple color. It has a boiling point of 279 ° C, and its molecular mass is 669.96 mol / L. The melting point ranges from 270-273 ° C.

Preparation

Generally, this pH indicator is used at a concentration of 0.1%, using 20% ​​ethyl alcohol as a solvent, since it is slightly soluble in water.

However, there are other substances that serve as solvents such as acetic acid, methyl alcohol, benzene, and certain alkaline solutions.

For the electrophoresis technique it is used at a concentration of (0.001%).

Use

PH indicator

It is one of the most frequently used pH indicators in chemical laboratories for acid-base titrations.

Stain in the electrophoresis technique

Bromothymol blue is used as a 0.001% dye in the separation of proteins by the polyacrylamide gel electrophoresis method (SDS-PAGE). This methodology is useful to control the addition of various protein raw materials in some processed foods such as sausages.

Bromophenol blue 0.05% is also used in the two-dimensional electrophoresis technique.

This utility is possible thanks to the fact that the bromophenol blue dye has a charge and moves easily in the gel, leaving a clearly visible blue-violet color in its path. In addition, it travels much faster than proteins and DNA molecules.

Therefore, bromophenol blue is excellent for marking the advancing front, allowing the electrophoresis to be stopped at the right time, without the risk that the molecules found in the run have come out of the gel.

Toxicity

Direct contact toxicity

In this sense, the NFPA (National Fire Protection Association) classifies this substance with a health risk (1), flammability (0) and reactivity (0). This means that it poses a low risk to health, and in fact there is no risk in the last two respects.

It is slightly irritating to the skin. In case of direct contact, it is recommended to immediately remove contaminated clothing and wash with plenty of water. When in contact with mucous membranes, wash immediately, if the affected person wears contact lenses, they should be removed immediately and seek medical assistance.

In case of inhalation, first aid such as artificial respiration and immediate medical attention should be applied.

If accidentally ingested, vomiting should be induced and 200 ml of water should be administered. Subsequently, the victim should be taken to the nearest medical center.

Genotoxicity study

Genetic toxicity studies to bromophenol blue have been performed using various methodologies, such as the Ames Salmonella / microsome technique, the L5178Y TK +/- mouse lymphoma assay, the mouse micronucleus assay, and the mitotic recombination with yeast Saccharomyces cerevisiae strain D5.

The studies carried out revealed that bromophenol blue has no genotoxic effect. That is, the trials determined that there was no genetic mutation, no chromosomal aberrations, and no primary DNA damage.

The genotoxicity study was necessary to carry out, because similar compounds from the structural point of view had shown mutagenic effects. However, it is now known that such effects are due to the presence of mutagenic impurities and not the compound itself.

Histological toxicity study

On the other hand, Haritoglou et al carried out an investigation where they evaluated the effect of new vital dyes in vivo in the short term for intraocular surgery. Among the dyes tested was bromophenol blue. The dye was dissolved in a balanced salt solution.

The researchers performed a vitrectomy (removal of the vitreous from the eye) in 10 pig eyes in vivo. Subsequently, they injected the dye into the cavity and allowed it to act for 1 minute, and then washed with saline solution. They also stained the lens capsule from the same eye. Subsequently the eyes were studied by light and electron microscopy.

Of all the dyes evaluated, bromophenol blue was the one that had the best response, staining at 2%, 1% and 0.2% and at the same time without causing histological changes that showed toxicity.

Therefore, it is emerging as the best candidate to be used in humans during retinovitreal surgeries, facilitating the visualization of the vitreous, the epiretinal membranes and the internal limiting membrane.

References

1. "Bromophenol blue." Wikipedia, The Free Encyclopedia. 9 May 2019, 09:12 UTC. 24 May 2019, 20:57 en.wikipedia.org.
2. López L, Greco B, Ronayne P, Valencia E. ALAN. 2006 Sep; 56 (3): 282-287. Available at: scielo.org.
3. Echeverri N, Ortiz, Blanca L, and Caminos J. (2010). Proteomic analysis of primary thyroid cultures. Colombian Journal of Chemistry, 39 (3), 343-358. Retrieved May 24, 2019, from scielo.org.
4. Lin GH, Brusick DJ. Mutagenicity studies on two triphenylmethane dyes, bromophenol blue and tetrabromophenol blue. J Appl Toxicol. 1992 Aug; 12 (4): 267-74.
5. Haritoglou C, Tadayoni R, May CA, Gass CA, Freyer W, Priglinger SG, Kampik A. Short-term in vivo evaluation of novel vital dyes for intraocular surgery. Retina. 2006 Jul-Aug; 26 (6): 673-8.