Phenol Red CAS 143-74-8

Phenol Red

Name	Phenol Red
Synonyms	Phenolsulfonephthalein; 3,3-Bis(p-hydroxyphenyl)-3H-2,1-benzoxathiole 1,1-dioxide
Molecular Structure
Molecular Formula	C19H14O5S
Molecular Weight	354.38
CAS Registry Number	143-74-8
EC Number	205-609-7

Uses:

1. Acid base indicator

Carbon dioxide concentration testing: 

Used as an indicator for measuring the concentration of carbon dioxide, for diagnostic auxiliary experiments.

Microbial culture medium detection: 

Determine the amount of acid produced by carbohydrate metabolism in the solution through colorimetric method, 

and monitor microbial metabolic activity.

Color change range: pH 6.8 (yellow) to 8.4 (red), neutral orange red.

2. Biological experiments

Cell culture: As a pH indicator for the culture medium, neutral appears red, acidic turns yellow (possibly contaminated),

and alkaline appears purple (requires adjustment of CO ₂ concentration).

Bacterial identification:

TSI Slope: Distinguishing Enterobacteriaceae bacteria (such as Salmonella and Escherichia coli) 

through differences in glucose/lactose fermentation and H ₂ S production.

Urea culture medium: urease producing bacteria decompose urea to produce ammonia, which turns phenol red into red.

3. Medical diagnosis

Phenol Red Excretion Test:

Functional assessment: Check liver and kidney function, diagnose diseases such as jaundice and stones.

4. Industrial applications

Display equipment and materials: used for sol gel matrix, photoreceptor, fuel cell, waveguide, etc.

Daily chemical products: used as ingredients in coatings, detergents, and cosmetics.

5. Other fields

Chromatographic analysis: as a chromatographic analysis reagent.

Extracellular vesicle research: used for labeling and tracking extracellular vesicles.