Indicators – Redox Titrimetry

Solid indicators such as those used in redox titrimetry are “dissolved” in inert salts that are marked on the labels. These are sold in amber-coloured 50 g bottles. They are ready for use.

It is important to understand that there are two different groups of redox indicators: pH independent and pH dependent.

pH Independent Redox Indicators

Indicator CAS Number E0 [mV]
Colour (ox – red)
Price
N-Phenylanthranilic acid  91-40-7  1,080 purple – colourless  $9.20
Na diphenylamine sulfonate  6152-67-6  840 violet – colourless  $12.40
Diphenylamine  122-39-4 760 violet – colourless  $9.20
Methyl Viologen Dichloride  75365-73-0 -430 colourless – blue  $62.00

pH Dependent Redox Indicators

E0 values are given for pH = 7

Indicator CAS Number E0 [mV]
Colour (ox – red)
Price
Thionine  78338-22-4 60 violet – colourless $16.60
Methylene Blue 7220-79-3  10 blue – colourless   $9.20
Neutral Red  553-24-2 -33 red – colourless   $9.20