Delloyd's Lab Tech resources reagents and Solutions

Color change pH acid base and metal ion indicators

Preparation of Titration Indicators

Complexometric, metal ion, EDTA indicators. Acid base pH indicators. Oxidation, redox and absorptionindicators.

Color change and pH range is given.EmailRelated link:Indicarors by categoryEDTA, Adsorption and Redox.

List of ph Acid-Base and metal ion titration Indicators

Search alphabetically by clicking a letter below to jump to the Indicator prep and info:

B C D E F G H I J K L M N O P Q R S T

U V W X Y Z

Amido black 10 B (redox)Dissolve 0.2 g dye in 100 ml of watercolor change = yellowish-brown to blueAlizarinDissolve 0.1g. in 100 ml. of 95% ethanol.pH =10.1 - 12.1; color change = red to purpleAlizarin yellowDissolve 0.1g. in 100 ml. of water.pH =10.0 - 12.1; color change = light yellow to brownish yellowAlizarin sulphonic acid Na saltDissolve 0.1g. in 100 ml. water or in 100 ml 1:1 ethanol and water.pH =4.3 - 6.3; color change = yellow to violetAlkali blueDissolve 0.1g. in 100 ml. of 95% ethanol.pH =9.4 - 14.0; color change = violet to pink

B

2.2'Bipyridin (iron(II) complex (redox)dissolve 0.695 g of FeSO4.7H2O and 1.171 g of 2.2'-bipyridin in 100 ml of watercolor change = pale blue to redBrillant cresyl blue (redox)dissolve 0.5 g in 100 ml of water or ethanol (96 %)color change = blue to colorlessBrilliant greenDissolve 0.1g. in 100 ml. of water.pH =0.0 - 2.6; color change = yellow to greenBromochlorophenol blueDissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.69 ml of 0.1M sodium hydroxide and make upto 100 ml with water.pH =3.0 - 4.6; color change = yellow to blue-violetBromocresol green

Dissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.58 ml of 0.1Msodium hydroxide and make upto 100 ml with water.pH =3.8 - 5.4; color change = yellow to blueBromocresol purpleDissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.4g in 0.74 ml of 0.1M sodium hydroxide and make upto 100 ml.pH =5.2 - 6.8; color change = yellow to purpleBromophenol blueDissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.6 ml of 0.1M sodium hydroxide and make upto 100 ml.pH =3.0 - 4.6; color change = yellow to blue-violetBromophenol redDissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.94 ml of 0.1M sodium hydroxide and make upto 100 ml.pH =5.2 - 6.8; color change = orange yellow to purpleBromothymol blueDissolve 0.1g. in 100 ml. of 20% ethanol.Bromo-oxylenol blueDissolve 0.1g. in 100 ml. of 95% ethanol.pH =5.7 - 7.5; color change = orange yellow to blue

C

Cacothelinesaturatedcolor change = yellow to red-violetCalcon also known as Solochrome Dark Blue or Eriochrome blue black R (metal-ion EDTA)sodium 1-(2- hydroxy-1-naphthylazo)-2-naphthol-4-sulphonate, Colour I ndex No.202;Dissolve 0.2g of the dyestuff in 50ml. of methanol.The colour change is from pink to pure blue.Calmagite1-(1-hydroxy-4-methyl-2-phenylazo)-2-naphthol-4-sulphonic acid (IX) (metal-ion EDTA)Can be substituted for Eriochrome Black T without change in the experimental procedures for calcium anmagnesium.It has same colour change, which is clearer and sharper, and aqueous solutions of the indicaare almost stable indefinitely.Dissolve 0.05g of calmagiite in 100ml. of water. The indicator is stable for at least 12 months when stored in apolythene bottle and in the dark.Chlorophenol redDissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.94 ml of 0.1M sodium hydroxide and make upto 100 ml.pH =4.8 - 6.4; color change = yellow to purpleCongo redDissolve 0.2g. in 100 ml. of water.pH =3.0 - 5.2; color change = blue to orange-yellowCresol purpleDissolve 0.04g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.86 ml of 0.1M sodium hydroxide and makeup to 100 ml.pH =7.4 - 9.0; color change = yellow to purpleCresol redDissolve 0.1g. in 100 ml. of 50% ethanol, or dissolve 0.04g in 1.05 ml of 0.1M sodium hydroxide and make upto 100 ml.pH =7.0 - 8.8; color change = yellow to purpleCresol redDissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 1.05 ml of 0.1M sodium hydroxide and make upto 100 ml.pH =0.2 - 1.8; color change = red to yellowm-Cresol purpleDissolve 0.04g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 1.05 ml of 0.1M sodium hydroxide and makeup to 100 ml.

pH =1.2 - 2.8; color change = red to yellowCrystal violetDissolve 0.1g. in 100 ml. of 70% ethanol.pH =0.8 - 2.6; color change = yellow to blue-violet

D

Dibromopyrogallol sulphone phthalein (VIII) (metal-ion EDTA) or Bromopyrogallol RedDissolve 0.05g of the reagent in 100ml. of 50% ethanol.The indicator is coloured orange-yellow in strongly acid solutions,; claret red in nearly neutral solutions; andviolet to blue in basic solutions.Dichlorofluorescein: (adsorption)Dissolve 0.1g in 60 - 70 % ethanol, orDissolve 0.1g of dichlorofluoroceinate in 100ml water.2.6-Dichlorophenolin-dophenol sodiumsalt (dihydrate) (redox)dissolve 0.02 g in 100 ml of watercolor change = blue to colorlessDi-iododimethylfluorescein:(adsorption) Dissolve 1g in 70 5 ethanol.4-(Dimethylamino) azobenzeneDissolve 0.1 to 1.5 g. in 100 ml. of 90% ethanol.pH =2.9 - 4.0; color change = red to yellow-orange3.3'-Dimethylnahthidine(4.4'-Diamino-3.3-dimethyl-1.1'-binaphthaline) (redox)dissolve 1.0 g in 100 ml of glacial acetic acidcolor change = purple-red to colorlessN,N-Dimethyl-1.4-phenylenediammonium dichloride (redox)dissolve 0.02 g in 100 ml of watercolor change = dark-blue to colorless2,5-DinitrophenolDissolve 0.05 to 0.1g. in 100 ml. of 70% ethanol.pH =4.0 - 5.8; color change = colorless to yellow2,4-DinitrophenolDissolve 0.1g. in 100 ml. of 70% ethanol.pH =2.8 - 4.7; color change = colorless to yellowDiphenylamine:Dissolve 1g in 100 ml conc. H2SO4color change = blue-violet to colorlessDiphenylamine-4-sulfonic acid barium salt (redox)Dissolve 0.2g in 100 ml watercolor change = red-violet to colorlessDiphenylamine-p-sulphonic acid (Na salt):(redox) Dissolve 0.2g in 100 ml water.Diphenylbenzidine:(redox) Dissolve 1g in 100 ml conc.H2SO4color change = violet to colorlessDiphenylcarbazide: (adsorption)Dissolve 0.1g in 100 ml ethanol.Diphenylcarbazone: (adsorption)Dissolve 0.1g in 100 ml ethanol or iso-propyl alcohol.

E

Eosin bluishDissolve 0.1g. in 100 ml. of water.pH =1.4 - 2.4; color change = colorless to pink fluorescenceEosin: (adsorption)Dssolve 0.1g in 100ml 70 % ethanol, or 0.1g of the sodium salt in 100 ml water.Eosin yellowishDissolve 0.1g. in 100 ml. of water.

pH =0.0 - 3.0; color change = yellow to green fluorescenceEpsilon blueDissolve 0.1g. in 100 ml. of water.pH =11.6 - 13.0; color change = orange to violetEriochrome Black T (metal-ion EDTA, also known as Solochrome black T or Mordant black)Sodium 1-(1-hydroxy-2-naphthalyzo)-6-nitro-2-naphthol-4-sulphonate (1); also known as Solochrome Blackor WDFA or No. 2 in the Colour Index. Not recommended for titration of solutions more acidic than Ph 6.5.Dissolve 0.2 g of the dyestuff in 15ml. of ethanolamine and add 5ml of absolute ethanol to reduce theviscosity; the reagent is stable for several months.A 0.4% solution of the pure dye in methanol may last for about a month.Colour change is from blue to red.Eriochrome blue black (See Calcon)Eriochrome Red Bsodium salt of 4-(2-hydroxy-4-sulpho-1-naphthylazo)-3-methyl-1-phenyl-2-pyrazolin-5-one (IX)---a pyrazoloneazo-B-naphthol dyestuff. (metal-ion EDTA)Dissolve 0.1g of the dyestuff in 50ml, ethanol. It is stable indefinitely.The colour change from pink to pale yellow is almost instantaneous at about 80oC.Erythrosin BDissolve 0.1g. in 100 ml. of water.pH =0.0 - 3.6; color change = orange to red

F G H I J K L

Fast Sulphon Black F (metal ion EDTA)Sodium salt of 1-hydrovy-8-(2-hydroxynaphthylazo)-2-(solphonaphtylazo)-3,6-disulphonic acid (V)The indicator solution is 0.5% solution in water.Specific colour change for copper is from magenta to pale blue to bright green.Ferric indicator: (adsorption)Use a saturated Ammonium Ferric sulphate soln. (~ 40%), add a few drops of 6M nitric acid, and use 1 meach titration.Ferroin: (redox)Make a 0.025M in water. or Dissolve 0.7g FeSO4.7H2O and 1.5g 1,10 o-phenanthroline in 100 ml water.color change = blue to orange-redFluorescein: (adsorption)Dissolve 0.2g in 100 ml 70 % alcohol, orDissolve 0.2g of sodium fluorocienate in 100 ml water.HHSNNA (metal-ion EDTA)See Patton and Reeder'sIndigo carmineDissolve 0.25g. in 100 ml. of 50% ethanol, or dissolve 1g in 100ml of water.pH =11.5 - 13.0; color change = blue to yellowIndigo carmine (Indigo disulfonate disodium salt) (redox)Dissolve 0.5g in 100 ml watercolor change = blue to yellowishLitmusDissolve 4g. in 100 ml. of water.pH =5.0 - 8.0; color change = red to blueNote on Litmus:You can purify the commercial litmus as follows: Digest 10g. of the litmus with 35ml.ofrectified spirit on a water bath for about 1 hr and decant the alcohol.; repeat this process twice. Extract theresidue several times with water and allow to stand for several days. Decant or siphon off the clear extract.This is of suitable concentration for most purposes.Bromo-cresol purple or Bromo-thymol blue are excellent substitutes for litmus.Azolitmin is the pure litmus colouring matter. Dissolve 0.1g. in 100ml of water.

M

Malachite green oxalateDissolve 0.1g. in 100 ml. of water.pH =0.0 - 2.0; color change = yellow to green-blue

N-Methlydiphenylamine-p-solphonic acid, (Na salt): (redox)Dissolve 0.1g in 100 ml water.Methylene blue (redox)Dissolve 0.1 to 0.5g in 100 ml waterMethyl greenDissolve 0.1g. in 100 ml. of water.pH =0.1 - 2.3; color change = yellow to blueMethyl orangeDissolve 0.05g. of the sodium salt in 100 mls. of water, add 8 mls..of 0.1M hydrochloric acid, and filter ifnecessary, orDissolve 0.05g. of the free acid in 100 ml. water, and filter the solution if a precipitate forms.pH =3.1 - 4.4; color change is pink/red towards yellow-orangeScreened methyl orangeDissolve 1g. of methyl orange and 1.4g. of xylene cyanol FF in 200ml. water and make up to 500 ml. vol. withethanol. The purpose of a screened or mixed indicator is to produce a more pronounced colour change atend point. These types of indicators consist of either a mixture of two indicators or a mixture of an indicatorand an inert dye. It changes colour at pH 3.8 -- 4.1 from violet to green.Methyl redDissolve 0.1g. of the Na salt in 100ml. of water, or dissolve in 30ml. of alcohol and dilute to 100ml. vol. withwater.pH =4.4 - 6.2; color change = red to yellow-orangeMethyl violetDissolve 0.1g. in 100 ml. of 20% ethanol.pH =0.1 - 2.7; color change = yellow to violetMethyl yellow Dissolve 0.1g. of the indicator in 100 ml of alcohol.Mixed indicatorDissolve 0.2g of methyl red and 0.1g of methyl blue or bromocresol green in 100 ml 95% ethanolpH =4.3 - 5.2; color change = green to pink(ph 4.5)Mordant black (See Eriochrome black T)Murexide (metal-ion EDTA)This is the Ammonium salt of purpuric acid.Suspend 0.5g of the powdered dyestuff in water, shake thoroughly and allow to settle. The saturatedsupernatant is used as the indicator.The colour change is towards a blue endpoint.

N

1-NapltolphthaleinDissolve 0.1g. in 100 ml. of 95% ethanol.pH =7.1 - 8.3; color change = brownish to blue-greenNeutral redDissolve 0.3g. in 100 ml. of 70% ethanol.pH =6.8 - 8.0; color change = blue-red to orange-yellowNeutral red (redox)Dissolve 0.5g in 100 ml of 95% ethanolcolor change = violet-red to colorlessNile blue (sulphate) (redox)Dissolve 0.1g in 100 ml watercolor change = blue-red to colorless3-NitrophenolDissolve 0.3g. in 100 ml. of 95% ethanol, or 0.08 g in 100 ml water.pH =6.6 - 8.6; color change = colorless to yellow-orange4-NitrophenolDissolve 0.2g. in 100 ml. of 95% ethanol, or 0.08g in 100 ml water.pH =5.4 - 6.8; color change = yellow to violet

O P

Patton and Reeders indicator (metal-ion EDTA)

2-hydroxy-1-(2-hydroxy-4-sulpho-1-naphthylazo)-3-naphthoic acid (111)Also known by the abbreviated name HHSNNA.The dyestuff is thoroughly mixed with 100 times its weight of sodium sulphate, and 1g of this mix is used foreach titration.Used in the direct titration of calcium, particularly in the presence of magnesium, pH range 12-14.A sharp colour change is obtained from wine red to pure blue.PhenolphthaleinDissolve 0.5 g. of the reagent in 50ml.of alcohol and add 50ml of water with stirring. Filter if a precipitateforms orDissolve 1g. of the dry indicator in 80 mls.ethylene glycol monoethyl ether (cellosolve) b.p.135oC, and diluteto 100ml. with distilled water.: the loss by evaporation is less by this preparation.Phenol redDissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 1.13 ml of 0.1M sodium hydroxide and make upto 100 ml.pH =6.4 - 8.2; color change = yellow to red-violetPentamethoxytriphenyl carbinolDissolve 0.1 g in 100 ml of 95% ethanolpH =1.2 - 3.2; color change = red to colorless1.10-Phenanthroline (monohydrate) (redox)Dissolve 0.695 g of FeSO4 x 7H2O and 1.487 g of 1.10-Phenanthroline in 100 ml of watercolor change = pale-blue to redN-Phenylanthranilic acid: (redox)Dissolve 0.1 g in 5 ml of 0.1M sodium hydroxide and make up to 100 ml with water.color change = purple-red to colorlessPicric acidDissolve 0.1 g in 100 ml of 20% ethanolpH =0.2 - 1.0; color change = colorlass to yellowPyrocatechol VioletPyrocatechol sulphone phthalein (VII); Catechol violet. (metal-ion EDTA)Dissolve 0.1g of the dyestuyy in 100ml.of water. This solution is stable for several weeks.Colour change is progressive, from yellow yo blue to green.

Q R S

Quinaldine redDissolve 0.1 g in 100 ml of 60% ethanolpH =1.4 - 3.2; color change = colorless to pinkRhodamine: (adsorption)Dissolve 0.05 g in 100 ml water.Safranin (redox)Dissolve 0.5g in 100 ml watercolor change = blue-violet(acidic),brown (alkaline) to colorless

T

4,5,6,7-Tetrabromo-phenolphthaleinDissolve 0.1 g in 100 ml of 95% ethanolpH =7.0 - 8.0; color change = colorless to purple2.2':6.2"-Terpyridine (iron(II) complex) (redox)Dissolve 0.232 g FeSO4 x 7H2O and 0.389 g of 2.2':6.2-terpyridine in 100 ml of watercolor change = pale-blue to redTertrazine: (redox)Dissolve 0.5g in water and use 4 drops per titration.Thionine (redox)Dissolve 0.5g in 100 ml of 95% ethanolcolor change = violet to colorlessTitan yellowDissolve 0.1 g in 100 ml of 20% ethanolpH =12.0 - 13.0; color change = yellow to red

Thymol blueDissolve 0.04g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.86 ml of 0.1M sodium hydroxide and makeup to 100 ml with water.pH =8.0 - 9.6; color change = yellow to blueThymol blueDissolve 0.04g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.86 ml of 0.1M sodium hydroxide and makeup to 100 ml with water.pH =1.2 - 2.8; color change = red to yellowThymolphthaleinDissolve 0.1 g in 100 ml of 50% ethanolpH =9.3 - 10.5; color change = yellow to redThymolphthalexoneThymolphthalein complexone (metal-ion EDTA)3,3-bis-[n,n-(carboxymethyl)aminomethyl] thymolphthalein (X)Prepare a 0.5% solution in ethanol.alternatively, a finely ground mixture 1:100 with AR potassium nitrate maybe used.Blue to colourless or slight pink in alkaline medium.Tropaeolin ODissolve 0.1g. of the solid in 100 ml of water.Tropaeolin OODissolve 0.1g. of the solid in 100 ml of water.

U V W X Y Z

Universal indicator (Full-range)Dissolve 0.026g thymol blue, 0.060g mrthyl red, 0.300g bromothymol blue, and 0.500g phenolphthalein inabout 500ml ethanol. Add dilute NaOH until solution turns green (neutral), Color changes from strong acid toalkaline: red to yellow to green (neutral) to blue to purple.Variamine Blue B (metal-ion EDTA)4-methoxy-4-amino-diphenylamineThe indicator solution is a 1% solution of the base in water. Ferric complex with EDTA - sharp change inredox potential - colourless to violet blue complex.Variamine blue salt B (redox)Dissolve 1.0 g in 100 ml of water or grind with sodium chloride or sodium sulfate anhydrous triturationcolor change = blue-violet(acidic),yellow (alkaline) to colorlessp-Xylenol blueDissolve 0.1g. in 100 ml. of 50% ethanol, or dissolve 0.04g in 0.98 ml of 0.1M sodium hydroxide and make upto 100 ml with water.pH =1.2 - 2.8; color change = red to yellowp-Xylenol blueDissolve 0.1g. in 100 ml. of 50% ethanol, or dissolve 0.04g in 0.98 ml of 0.1M sodium hydroxide and make upto 100 ml with water.pH =8.0 - 9.6; color change = yellow to blueXylenol Orange3,3-bis[NN-di-(carboxymethyl)-aminomethyl]-o-cresolsulphonephthalein (VI)Dissolve 0.5g of xylenol orange indicator in 100ml. of water. The solution is stable indeffinitely.Acid solutions are coloured lemon yellow and those of the metal complexes intensely red.

Back to Top

delloyd.50megs.com

Back to Top

Signature: Dhanlal De Lloyd, Chem. Dept, The University of The West Indies, St. Augustine campusThe Republic of Trinidad and Tobago.

Copyright: delloyd2000© All rights reserved.