Tashiro's indicator

Tashiro's indicator is a pH indicator (pH value: 4.4–6.2), mixed indicator composed of a solution of methylene blue (0.1%) and methyl red (0.03%) in ethanol or in methanol.

It can be used e.g. for the titration of ammonia in Kjeldahl analysis.

Colours

• In acids: violet
• At equivalence point (pH 5.2): grey
• In bases: green

Methylene blue functions to change the red-yellow shift of methyl red to a more distinct violet-green shift.

See also

• Litmus
• pH Indicator

References

1. Tashiro
2. Kjeldahl method
3. Methyl red
4. Shiro Tashiro
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