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Star Republic: Guide for Biologists

pH indicators

Indicator

pH Range

Acid

Base

2,4-Dinitrophenol

2.4-4.0

colorless

yellow

Alizarin Red S

4.6 - 6.0

Alizarin sodium sulfonate

3.7-5.2

yellow

violet

Alizarin yellow

10.0-12.0

yellow

lilac

a-Naphtholbenzein

9.0-11.0

yellow

blue

a-Naphtholphthalein

7.3-8.7

rose

green

a-Naphthyl red

3.7-5.0

red

yellow

Azolitmin

5.0-8.0

red

blue

Brilliant Green

0.0 - 2.6

Bromcresol green

4.0-5.6

yellow

blue

Bromcresol purple

5.2-6.8

yellow

purple

Bromphenol blue

3.0-4.6

yellow

blue-violet

Bromphenol blue

6.2-7.6

yellow

blue

Chlorophenol Red

4.8 - 6.4

Chlorphenol red

5.4-6.8

yellow

red

Congo Red

3.0 - 5.0

Cresol red

7.2-8.8

yellow

red

Diazo violet

10.1-12.0

yellow

violet

Eosin Y

0.0 - 3.0

m-Cresol Purple

1.2 - 2.8

m-Cresol Red

2.0 - 3.0

Methyl orange

3.1-4.4

red

orange

Methyl Purple

4.8 - 5.4

Methyl red

4.4-6.2

red

yellow

Methyl Violet

0.1 - 3.2

Methyl yellow

2.9-4.0

red

yellow

Neutral red

6.8-8.0

red

yellow

Nile blue

10.1-11.1

blue

red

Nitramine

11.0-13.0

colorless

orange-brown

Pentamethoxy red

1.2-2.3

red-violet

colorless

p-Ethoxychrysoidine

3.5-5.5

red

yellow

Phenol red

6.4-8.0

yellow

red

Phenolphthalein

8.0 - 10

Phenolphthalein

8.0-10.0

colorless

red

p-Nitrophenol

5.0-7.0

colorless

yellow

Poirrier's blue

11.0-13.0

blue

violet-pink

Rosolic acid

6.8-8.0

yellow

red

Salicyl yellow

10.0-12.0

yellow

orange-brown

Sulfo Orange

11.0 - 12.6

Tetrabromphenol blue

3.0-4.6

yellow

blue

Thymol Blue

1.2-2.8

red

yellow

Thymol blue

8.0-9.6

yellow

blue

Thymolphthalein

9.4-10.6

colorless

blue

Trinitrobenzoic acid

12.0-13.4

colorless

orange-red

Tropeolin O

11.0-13.0

yellow

orange-brown

Tropeolin OO

1.3-3.2

red

yellow

Tropeolin OOO

7.6-8.9

yellow

rose-red