Skip to content
Login Register

#phenol red

2 public questions tagged with this topic.

Animal Tissue Culture 1

Phenol red in culture media is used as:

Visual pH monitoring without invasive electrodes that breach sterility risking bacterial contamination is accomplished via chemical indicator phenol red also called phenolsulfonphthalein, molecular weight 354.38 daltons, pKa 7.9 at 37°C making transition range 6.8 to 8.2 overlapping physiological pH of culture. Structure triphenylmethane dye exists in equilibrium between protonated yellow form absorbing maximally 430 nanometers and deprotonated red anionic form with extensive conjugated quinone system absorbing 560 nanometers, isosbestic point near 480 nanometers. At physiological pH mixture a

Ref: Freshney 7th ed phenol red pKa 7.9 indicator nontoxic; Sigma media phenolsulfonphthalein yellow red transition estrogenic caution.

View Details
Basic Applied Biology

Phenol red in culture media acts as:

Phenol red chemically phenolsulfonphthalein, sulfonephthalein class dye, serves as visual pH indicator deliberately incorporated at 5 to 15 mg per L in many mammalian culture media including Dulbecco Modified Eagle Medium, RPMI 1640 and Minimum Essential Medium to allow non-invasive monitoring of acid-base status. Color transition results from protonation equilibrium with pKa approximately 7.9 at 37 Celsius and ionic strength of media: acidic protonated form absorbs at 430 nanometer appearing yellow below pH 6.8, partially deprotonated neutral form appears orange-red around pH 7.4 physiologica

Ref: Freshney Ch indicators; Berthois et al. Proc Natl Acad Sci USA 1986 phenol red estrogen; NCBI media formulation guide.

View Details