| ACID-BASE INDICATORS |
| Indicator | Colour Change | Interval | Preparation |
| Malachite green oxalate | Yellow / Green-blue | 0.0 - 2.0 | 0.1g in 100ml water |
| Brilliant green | Yellow / Green | 0.0 - 2.6 | 0.1g in 100ml water |
| Eosin yellowish | Yellow / Fluorescent green | 0.0 - 3.0 | 0.1g in 100ml water |
| Erythrosin B | Orange / Red | 0.0 - 3.6 | 0.1g in 100ml water |
| Methyl green | Yellow / Blue | 0.1 - 2.3 | 0.1g in 100ml water |
| Methyl violet | Yellow / Violet | 0.1 - 2.7 | 0.1g in 100ml ethanol (20%) |
| Picric acid | Colourless / Yellow | 0.2 - 1.0 | 0.1g in 100ml ethanol (20%) |
| Cresol red | Red / Yellow | 0.2 - 1.8 | 0.1g in 100ml ethanol (20%) |
| Crystal violet | Yellow / Blue-violet | 0.8 - 2.6 | 0.1g in 100ml ethanol (70%) |
| m-Cresol purple | Red / Yellow | 1.2 - 2.8 | 0.04g in 100ml ethanol (20%) |
| Thymol blue | Red / Yellow | 1.2 - 2.8 | 0.04g in 100ml ethanol (20%) |
| p-Xylenol blue | Red / Yellow | 1.2 - 2.8 | 0.1g in 100ml ethanol (50%) |
| Eoisin bluish | Colourless / Fluorescent pink | 1.4 - 2.4 | 0.1g in 100ml water |
| Quinaldine red | Colourless / Pink | 1.4 - 3.2 | 0.1g in 100ml ethanol (60%) |
| 2,4-Dinitrophenol | Colourless / Yellow | 2.8 - 4.7 | 0.1g in 100ml ethanol (70%) |
| 4-(Dimethylamino)azobenzene | Red / Yellow-orange | 2.9 - 4.0 | 0.3g in 100ml ethanol (90%) |
| Bromochlorophenol blue | Yellow / Blue-violet | 3.0 - 4.6 | 0.1g in 100ml ethanol (20%) |
| Bromophenol blue | Yellow / Blue-violet | 3.0 - 4.6 | 0.1g in 100ml ethanol (20%) |
| Congo red | Blue / Yellow-orange | 3.0 - 5.2 | 0.2g in 100ml water |
| Methyl orange | Blue / Yellow-orange | 3.1 - 4.4 | 0.04g in 100ml ethanol (20%) |
| Methyl orange solution | Red / Yellow-orange | 3.1 - 4.4 | 0.04g in 100ml ethanol (20%) |
| Bromocresol green | Yellow / Blue | 3.8 - 5.4 | 0.1g in 100ml ethanol (20%) |
| 2,5-Dinitrophenol | Colourless / Yellow | 4.0 - 5.8 | 0.07g in 100ml ethanol (70%) |
| Alizarinsulfonic acid sodium salt | Yellow / Violet | 4.3 - 6.3 | 0.1g in 100ml ethanol (50%) |
| Methyl red | Red / Yellow-orange | 4.4 - 6.2 | 0.1g in 100ml ethanol (96%) |
| Methyl red sodium salt | Red / Yellow-orange | 4.4 - 6.2 | 0.1g in 100ml water |
| Chlorophenol red | Yellow / Purple | 4.8 - 6.4 | 0.1g in 100ml ethanol (20%) |
| Bromocresol purple | Yellow / Purple | 5.2 - 6.8 | 0.1g in 100ml ethanol (20%) |
| Bromophenol red | Orange-yellow / Purple | 5.2 - 6.8 | 0.1g in 100ml ethanol (20%) |
| 4-Nitrophenol | Colourless / Yellow | 5.4 - 7.5 | 0.2g in 100ml ethanol (96%) |
| Bromoxylenol blue | Yellow / Blue | 5.7 - 7.5 | 0.1g in 100ml ethanol (96%) |
| Alizarin | Yellow / Red | 5.8 - 7.2 | 0.5g in 100ml ethanol (96%) |
| Bromothymol blue | Yellow / Blue | 6.0 - 7.6 | 0.1g in 100ml ethanol (20%) |
| Phenol red | Yellow / Red-violet | 6.4 - 8.2 | 0.1g in 100ml ethanol (20%) |
| 3-Nitrophenol | Colourless / Yellow-orange | 6.6 - 8.6 | 0.3g in 100ml ethanol (96%) |
| Neutral red | Blue-red / Orange-yellow | 6.8 - 8.0 | 0.3g in 100ml ethanol (70%) |
| 4,5,6,7-Tetrabromophenolphthalein | Colourless / Purple | 7.0 - 8.0 | 0.1g in 100ml ethanol (96%) |
| Cresol red | Orange / Purple | 7.0 - 8.8 | 0.1g in 100ml ethanol (50%) |
| 1-Naphtolphthalein | Brown - Blue-green | 7.1 - 8.3 | 0.1g in 100ml ethanol (96%) |
| Cresol purple | Yellow / Purple | 7.4 - 9.0 | 0.04g in 100ml ethanol (20%) |
| Thymol blue | Yellow / Blue | 8.0 - 9.6 | 0.04g in 100ml ethanol (20%) |
| p-Xylenol blue | Yellow / Blue | 8.0 - 9.6 | 0.1g in 100ml ethanol (50%) |
| Phenolphthalein | Colourless / Red-violet | 8.2 - 9.8 | 0.1g in 100ml ethanol (96%) |
| Thymolphthalein | Colourless / Blue | 9.3 - 10.5 | 0.1g in 100ml ethanol (50%) |
| Alkali blue | Violet / Pink | 9.4 - 14.0 | 0.1g in 100ml ethanol (96%) |
| Alizarin yellow GG | Light yellow / Brown-yellow | 10.0 - 12.1 | 0.1g in 100ml water |
| Alizarin | Red / Purple | 10.1 - 12.1 | 0.5g in 100ml ethanol (96%) |
| Titan yellow | Yellow / Red | 12.0 - 13.0 | 0.1g in 100ml ethanol (20%) |
| Indigo carmine | Blue / Yellow | 11.5 - 13.0 | 0.25g in 100ml ethanol (50%) |
| Epsilon blue | Orange / Violet | 11.6 - 13.0 | 0.1g in 100ml water |
| REDOX INDICATORS |
| Indicator | Redox potential
E0[V] Em[V]
(pH=0) (pH=7)
20oC 30oC | rH | Colour change
oxidised form | Preparation |
| Amido black 10 B | +0.57 +0.84 | | Yellow-brown / Blue | 0.2g in 100ml water |
| 2,2'-Bipyridin (iron(II) complex) | +1.03 | | Pale blue / Red | 0.695g FeSO4.7H2O & 1.171g 2,2'-bipyridin in 100ml water |
| Brilliant cresyl blue | +0.58 +0.05 | | Blue / Colourless | 0.5g in 100ml water |
| 2,6-Dichlorophenolindophenol sodium salt (dihydrate) | +0.67 +0.23 | 22 | Blue / Colourless | 0.02g in 100ml water |
| 3,3'-Dimethylnaphthidine | +0.78 | | Purple-red / Colourless | 1.0g in 100ml glacial acetic acid |
| N,N-Dimethyl-1,4-phenylenediammonium dichloride | +0.75 | | Dark blue / Colourless | 0.2g in 100ml water |
| Diphenylamine | +0.76 | | Blue-violet / Colourless | 1.0g in 100ml sulphuric acid (96%) |
Ferroin
(1,10-Phenanthroline iron(II) complex) | +1.06 | 40 | Blue / Orange-red | |
Indigo carmine
(Indigo disulfonate disodium salt) | +0.29 -0.11 | 10 | Blue / Yellow | 0.05g in 100ml water |
| Methylene blue | +0.53 +0.01
(30oC) | 14.5 | Blue / Colourless | 0.3g in 100ml water |
| Neutral red | +0.24 -0.29 | 3 | Violet-red / Colourless | 0.05g in 100ml ethanol (96%) |
| Nile blue (sulphate) | +0.41 -0.12 | | Blue-red / Colourless | 0.1g in 100ml water |
| 1,10-Phenanthroline (monohydrate) | +1.14 +1.06 | | Pale blue / Red | 0.695g FeSO4.7H2O & 1.487g 1,10-Phenanthroline in 100ml water |
| N-Phenylanthranilic acid | +0.89 | | Purple-red / Colourless | 0.1g in 5ml 0.1M NaOH; make up to 100ml with water |
| Safranin | +0.24 -0.29 | 4 | Blue-violet / Colourless | 0.05g in 100ml water |
| Thionine | +0.56 +0.06 | 16 | Violet / Colourless | 0.05g in 100ml ethanol (60%) |
| Variamine blue salt B | +0.71 +0.31 | | Blue-violet / Colourless | 1.0g in 100ml water |