| Indicator | pH
Range | Colour
Change | Preparation |
|
| Methyl
violet | 0.0 | 1.0 |
yellow | blue |
0.01-0.05% in water |
|
Crystal violet | 0.0 | 1.8 |
yellow | blue |
0.02% in water |
|
Ethyl violet | 0.0 |
2.4 |
yellow | blue |
0.1% in 50% methanol/water |
| Malachite
green | 0.2 | 1.8 | yellow | blue-green | water |
| Methyl green
| 0.2 |
1.8 |
yellow | blue |
0.1% in water |
|
2-(p-dimethylaminophenylazo)pyridine |
0.2 |
1.8 |
yellow | blue |
0.1% in ethanol |
|
2-(p-dimethylaminophenylazo)pyridine |
4.4 |
5.6 |
red | yellow |
0.1% in ethanol |
|
Cresol Red (o-cresolsulfonephthalein) | 0.4 | 1.8 |
yellow | red |
0.1% in 0.001048 M NaOH(aq) |
| Cresol Red (o-cresolsulfonephthalein) | 7.0 | 8.8 |
yellow | red |
0.1% in 0.001048 M NaOH(aq) |
| Quinaldine
Red | 1.0 | 2.2 |
colourless | red |
1% in ethanol |
Paramethyl Red (p-(p-dimethyl
aminophenylazo)-benzoic acid,
sodium salt) | 1.0 | 3.0 |
red | yellow |
ethanol |
|
Metanil Yellow | 1.2 | 2.4 |
red | yellow |
0.01% in water |
|
4-phenylazodiphenylamine | 1.2 | 2.6 |
red | yellow |
0.01% in 0.01 M HCl in 50%ethanol/water |
|
Thymol blue (thymolsulfonephthalein) |
1.2 | 2.8 |
red | yellow |
0.04% in 0.0086 M NaOH |
|
Thymol blue (thymolsulfonephthalein) |
8.0 | 9.6 |
yellow | blue |
0.04% in 0.0086 M NaOH |
Metacresol purple
(m-cresolsulfonephthalein) | 1.2 | 2.8 |
red | yellow |
0.04% in 0.01048 M NaOH |
Metacresol purple
(m-cresolsulfonephthalein) | 7.4 | 9.0 |
yellow | purple |
0.04% in 0.01048 M NaOH |
Orange IV (p-(p-anilinophenylazo)
benzenesulfonic acid, sodium
salt) | 1.4 | 2.8 |
red | yellow |
0.01% in water |
|
4-o-tolylazo-o-toluidine | 1.4 | 2.8 |
orange | yellow |
water |
|
Erythrosine, disodium salt |
2.2 | 3.6 |
orange | red |
0.1% in water |
|
Benzopurpurine 48 | 2.2 | 4.2 |
violet | red |
0.1% in water |
|
N,N-dimethyl-p-(m-tolylazo)aniline |
2.6 | 4.8 |
red | yellow |
0.1% in water |
4,4'-bis(2-amino-1-naphthylazo)2,2'-
stilbenedisulfonic acid | 3.0 | 4.0 |
purple | red |
0.1% in 0.00295 M NaOH |
Tetrabromophenolphthaleinethyl ester,
potassium salt |
3.0 | 4.2 |
yellow | blue |
0.1% in ethanol |
Bromophenol blue
(3',3",5',5"-tetrabromophenolsulfonephthalein) | 3.0 | 4.6 |
yellow | blue |
0.04% in 0.000596 M NaOH |
|
2,4-dinitrophenol | 2.8 | 4.0 |
colourless | yellow |
saturated in water |
|
N,N-dimethyl-p-phenylazoaniline | 2.8 | 4.4 |
red | yellow |
0.1% in 90% ethanol/water |
|
Congo red | 3.0 | 5.0 |
blue | red |
0.1% in water |
|
Methyl orange-xylene cyanole solution | 3.2 | 4.2 |
purple | green |
ready solution |
|
Methyl orange | 3.2 | 4.4 |
red | yellow |
0.01% in water |
|
Ethyl orange | 3.4 | 4.8 |
red | yellow |
0.05-0.2% in water |
4-(4-dimethylamino-1-naphthylazo)-3-
methoxybenzenesulfonic
acid | 3.5 | 4.8 |
violet | yellow |
0.1% in 60% ethanol |
Bromocresol green (3',3",5',5"-tetrabromo-m-
cresolsulfonephthalein) | 3.8 | 5.4 |
yellow | blue |
0.04% in 0.00572 M NaOH |
|
Resazurin | 3.8 | 6.4 |
orange | violet |
water |
|
4-phenylazo-1-naphthylamine | 4.0 | 5.6 |
red | yellow |
0.1% in ethanol |
|
2-(p-dimethylaminophenylazo)-pyridine |
0.2 | 1.8 |
yellow | red |
0.1% in ethanol |
|
2-(p-dimethylaminophenylazo)-pyridine |
4.4 | 5.6 |
red | yellow |
0.1% in ethanol |
4-(p-ethoxyphenylazo)-m-phenylenediamine
monohydrochloride | 4.4 | 5.8 |
orange | yellow |
0.1% in water |
|
Lacmoid | 4.4 | 6.2 |
red | blue |
0.2% in ethanol |
|
Alizarin red S | 4.6 | 6.0 |
yellow | red |
dilute in water |
|
Methyl red | 4.8 | 6.0 |
red | yellow |
0.02% in 60% ethanol/water |
|
Propyl red | 4.8 | 6.6 |
red | yellow |
ethanol |
Bromocresol purple
(5',5"-dibromo-o-cresolsulfone-phthalein) |
5.2 | 6.8 |
yellow | purple |
0.04% in 0.0074 M NaOH |
Chlorophenol red
(3',3"-dichlorophenolsulfonephthalein) | 5.2 | 6.8 |
yellow | red |
0.04% in 0.00944 M NaOH |
|
p-nitrophenol |
5.4 | 6.6 |
colourless | yellow |
0.1% in water |
|
Alizarin | 5.6 | 7.2 |
yellow | red |
0.1% in methanol |
|
Alizarin | 11.0 | 12.4 |
red | purple |
0.1% in methanol |
2-(2,4-dinitrophenylazo)-1-naphthol-3,6-
disulfonic acid, disodium
salt | 6.0 | 7.0 |
yellow | blue |
0.1% in water |
Bromothymol blue
(3',3"-dibromothymolsulfonephthalein) | 6.0 | 7.6 |
yellow | blue |
0.04% in 0.0064 M NaOH |
|
m-dinitrobenzoylene urea |
6.4 | 8.0 |
colourless | yellow |
|
| Brilliant yellow | 6.6 | 7.8 |
yellow | orange |
1% in water |
|
Phenol red (phenolsulfonephthalein) |
6.6 | 8.0 |
yellow | red |
0.04% in 0.01128 M NaOH |
|
Neutral red | 6.8 | 8.0 |
red | amb |
0.01% in 50% ethanol/water |
|
m-nitrophenol |
6.8 | 8.6 |
colourless | yellow |
0.3% in water |
|
Cresol red (o-cresolsulfonephthalein) | 0.0 | 1.0 |
red | yellow |
0.04% in 0.01048 M NaOH |
|
Cresol red (o-cresolsulfonephthalein) | 7.0 | 8.8 |
yellow | red |
0.04% in 0.01048 M NaOH |
|
Curcumin |
7.4 | 8.6 |
yellow | red |
ethanol |
|
Curcumin |
10.2 | 11.8 |
| |
ethanol |
Metacresol purple
(m-cresolsulfonephthalein) | 1.2 | 2.8 |
red | yellow |
0.04% in 0.01048 M NaOH |
Metacresol purple
(m-cresolsulfonephthalein) | 7.4 | 9.0 |
yellow | purple |
0.04% in 0.01048 M NaOH |
4,4'-bis(4-amino-1-naphthylazo)-2,2'-
stilbene disulfonic acid |
8.0 | 9.0 |
blue | red |
0.1% in 0.00295 M NaOH |
Thymol
blue
(thymolsulfonephthalein) | 1.2 | 2.8 | red | yellow | 0.04%
in 0.0086 M NaOH |
Thymol
blue
(thymolsulfonephthalein) | 8.0 | 9.6 | | | 0.04%
in 0.0086 M NaOH |
|
o-cresolphthalein |
8.2 | 9.8 |
colourless | red |
0.04% in ethanol |
|
p-naphtholbenzene | 8.2 | 10.0 |
orange | blue |
1% in dilute alkali |
|
Phenolphthalein |
8.2 | 10.0 |
colourless | pink |
0.05% in 50% ethanol/water |
|
Ethyl-bis(2,4-dimethylphenyl)acetate | 8.4 | 9.6 |
colourless | blue |
saturated solution in 50% acetone/ethanol |
| Thymolphthalein |
9.4 | 10.6 |
colourless | blue |
0.04% in 50% ethanol/water |
Alizarin yellow R (5-(p-
nitrophenylazo)salicylic acid, sodium
salt) | 10.1 | 12.0 |
yellow | red |
0.01% in water |
p-(2,4-dihydroxyphenylazo)benzene
sulfonic acid, sodium salt) |
11.4 | 12.6 |
yellow | orange |
0.1% in water |
|
5,5'-indigosulfonic acid, disodium salt | 11.4 | 13.0 |
blue | yellow |
water |
|
2,4,6-trinitrotoluene |
11.5 | 13.0 |
colourless | orange |
0.1-0.5% in ethanol |
|
1,3,5-trinitrobenzene | 12.0 | 14.0 |
colourless | orange |
0.1-0.5% in ethanol |
|
Clayton yellow |
12.2 | 13.2 |
yellow | amb |
0.1% in water |