Indicators

Liquid indicators are dissolved in 60% propan-2-ol, in consideration of the restrictions on ethanol in most Canadian jurisdictions.

The CAS numbers in the tables refer only to the indicator itself, and not to other ingredients.

All indicators are produced by the Avalon Institute, and are products “Made in Canada.” Prices are in Canadian dollars.

 

pH Titrations (Acidimetry & Alkalimetry)

These are sold in amber-coloured 50 ml dropper bottles. The solutions are ready to use.

Indicator CAS Number pH Range Colour Price
Malachite Green  123333-61-9  0.2 – 1.8  blue – green  $11.20
Congo Red  573-58-0  3.0 – 5.2  blue – red  $11.20
Methyl Orange  547-58-0 3.1 – 4.4 red – yellow  $11.20
Tashiro Indicator N/A  4.2 – 6.3  purple – green  $11.20
 Bromothymol Blue  76-59-5  6.0 – 7.6  yellow – blue  $11.20
 Neutral Red  553-24-2  6.8 – 8.0  red – yellow  $11.20
 Phenolphthalein  77-09-8  8.2 – 10.0  none – red  $11.20

Complexometry

Solid indicators such as those used in complexometry 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.

Indicator CAS Number Price
Calconcarboxylic Acid  3737-95-9  $9.20
Calmagite 3147-14-6   $9.20
Eriochrome® Black T  1787-61-7   $9.20
Pyrocatechol Violet 115-41-3  $9.20
Xylenol Orange  3618-43-7   $9.20

Eriochrome® is a registered trademark of Ciba-Geigy (now Novartis).

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: Thos that are pH independent, and those that are 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