Universal indicator

[1] Although there are several commercially available universal pH indicators, most are a variation of a formula patented by Yamada in 1933.

[2][3][4] A universal indicator is usually composed of water, 1-propanol, phenolphthalein, sodium hydroxide, methyl red, bromothymol blue, sodium bisulfite, and thymol blue.

Colour matching charts are supplied with the specific test strips purchased.

The impact of an ethanol-based universal indicator may seem negligible at first glance.

However, in the case of dilute solutions prepared with bidistilled water, this influence becomes readily discernible and measurable.