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Cresol red indicator
CAS: 1733-12-6 EC Number: 217-064-2 Formula: C₂₁H₁₈O₅S Molecular Weight: 382.43

0.04%(w/v) in water

In Stock Item #: C196466

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Technical Identifiers

IUPAC Name

4-[3-(4-hydroxy-3-methylphenyl)-1,1-dioxo-2,1λ6-benzoxathiol-3-yl]-2-methylphenol

SMILES

CC1=C(C=CC(=C1)C2(C3=CC=CC=C3S(=O)(=O)O2)C4=CC(=C(C=C4)O)C)O

InChIKey
OBRMNDMBJQTZHV-UHFFFAOYSA-N

InChI

1S/C21H18O5S/c1-13-11-15(7-9-18(13)22)21(16-8-10-19(23)14(2)12-16)17-5-3-4-6-20(17)27(24,25)26-21/h3-12,22-23H,1-2H3

Synonyms
AKOS000813825 | NSC7224 | NSC-7224 | Cresol red indicator | D89243 | BS-43766 | CresolRed | FT-0640840 | CRESOL RED [...
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Cresol red indicator
CAS: 1733-12-6 EC Number: 217-064-2 Formula: C₂₁H₁₈O₅S Molecular Weight: 382.43

0.2%(w/v) in water

In Stock Item #: C196467

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Technical Identifiers

IUPAC Name

4-[3-(4-hydroxy-3-methylphenyl)-1,1-dioxo-2,1λ6-benzoxathiol-3-yl]-2-methylphenol

SMILES

CC1=C(C=CC(=C1)C2(C3=CC=CC=C3S(=O)(=O)O2)C4=CC(=C(C=C4)O)C)O

InChIKey
OBRMNDMBJQTZHV-UHFFFAOYSA-N

InChI

1S/C21H18O5S/c1-13-11-15(7-9-18(13)22)21(16-8-10-19(23)14(2)12-16)17-5-3-4-6-20(17)27(24,25)26-21/h3-12,22-23H,1-2H3

Synonyms
AKOS000813825 | NSC7224 | NSC-7224 | Cresol red indicator | D89243 | BS-43766 | CresolRed | FT-0640840 | CRESOL RED [...
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Thymolphthalein indicator
CAS: 125-20-2 EC Number: 204-729-7 PubChem CID: 31316 Formula: C₂₈H₃₀O₄ Molecular Weight: 430.54

90% (v/v) ethanol containing 0.05% (w/v)

In Stock Item #: T196524

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Synonyms
1(3H)-Isobenzofuranone,3-bis[4-hydroxy-2-methyl-5-(1-methylethyl)phenyl]- | 3,3-bis(4-hydroxy-2-methyl-5-propan-2-ylp...
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Crystal violet indicator
CAS: 548-62-9 EC Number: 208-953-6 Formula: C₂₅H₃₀N₃Cl Molecular Weight: 407.98

0.1%(w/v)in Acetic Acid

In Stock Item #: C196469

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IUPAC Name

[4-[bis[4-(dimethylamino)phenyl]methylidene]cyclohexa-2,5-dien-1-ylidene]-dimethylazanium;chloride

SMILES

CN(C)C1=CC=C(C=C1)C(=C2C=CC(=[N+](C)C)C=C2)C3=CC=C(C=C3)N(C)C.[Cl-]

InChIKey
ZXJXZNDDNMQXFV-UHFFFAOYSA-M

InChI

1S/C25H30N3.ClH/c1-26(2)22-13-7-19(8-14-22)25(20-9-15-23(16-10-20)27(3)4)21-11-17-24(18-12-21)28(5)6;/h7-18H,1-6H3;1H/q+1;/p-1

Synonyms
Caswell No. 264A | Gentioletten | Blaues pyoktanin | C.I. Basic violet 3 | Methyl Violet 6B (biological stain) | Badi...
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Crystal violet indicator
CAS: 548-62-9 EC Number: 208-953-6 Formula: C₂₅H₃₀N₃Cl Molecular Weight: 407.98

Liquid 1% in Acetic Acid

In Stock Item #: C196470

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Technical Identifiers

IUPAC Name

[4-[bis[4-(dimethylamino)phenyl]methylidene]cyclohexa-2,5-dien-1-ylidene]-dimethylazanium;chloride

SMILES

CN(C)C1=CC=C(C=C1)C(=C2C=CC(=[N+](C)C)C=C2)C3=CC=C(C=C3)N(C)C.[Cl-]

InChIKey
ZXJXZNDDNMQXFV-UHFFFAOYSA-M

InChI

1S/C25H30N3.ClH/c1-26(2)22-13-7-19(8-14-22)25(20-9-15-23(16-10-20)27(3)4)21-11-17-24(18-12-21)28(5)6;/h7-18H,1-6H3;1H/q+1;/p-1

Synonyms
Caswell No. 264A | Gentioletten | Blaues pyoktanin | C.I. Basic violet 3 | Methyl Violet 6B (biological stain) | Badi...
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Crystal violet indicator
CAS: 548-62-9 EC Number: 208-953-6 Formula: C₂₅H₃₀N₃Cl Molecular Weight: 407.98

0.2%(w/v)in Acetic Acid

Out of Stock Item #: C196468

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Technical Identifiers

IUPAC Name

[4-[bis[4-(dimethylamino)phenyl]methylidene]cyclohexa-2,5-dien-1-ylidene]-dimethylazanium;chloride

SMILES

CN(C)C1=CC=C(C=C1)C(=C2C=CC(=[N+](C)C)C=C2)C3=CC=C(C=C3)N(C)C.[Cl-]

InChIKey
ZXJXZNDDNMQXFV-UHFFFAOYSA-M

InChI

1S/C25H30N3.ClH/c1-26(2)22-13-7-19(8-14-22)25(20-9-15-23(16-10-20)27(3)4)21-11-17-24(18-12-21)28(5)6;/h7-18H,1-6H3;1H/q+1;/p-1

Synonyms
Caswell No. 264A | Gentioletten | Blaues pyoktanin | C.I. Basic violet 3 | Methyl Violet 6B (biological stain) | Badi...
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Phenol red indicator
CAS: 143-74-8 Formula: C₁₉H₁₄O₅S Molecular Weight: 354.38

0.1%(w/v)in water

In Stock Item #: P196504

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Technical Identifiers

IUPAC Name

4-[3-(4-hydroxyphenyl)-1,1-dioxo-2,1λ6-benzoxathiol-3-yl]phenol

SMILES

C1=CC=C2C(=C1)C(OS2(=O)=O)(C3=CC=C(C=C3)O)C4=CC=C(C=C4)O

InChIKey
BELBBZDIHDAJOR-UHFFFAOYSA-N

InChI

1S/C19H14O5S/c20-15-9-5-13(6-10-15)19(14-7-11-16(21)12-8-14)17-3-1-2-4-18(17)25(22,23)24-19/h1-12,20-21H

Synonyms
3,3-bis(4-hydroxyphenyl)-3H-2,1lambda6-benzoxathiole-1,1-dione | 4,4'-(3H,2,1-Benzoxathiol-3-ylidene)bisphenol S,S-di...
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Sulfo orange
CAS: 547-57-9 PubChem CID: 2728027 Formula: C₁₂H₉N₂NaO₅S Molecular Weight: 316.27

0.4%

Out of Stock Item #: S196522

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IUPAC Name

sodium;4-[(2,4-dihydroxyphenyl)diazenyl]benzenesulfonate

SMILES

C1=CC(=CC=C1N=NC2=C(C=C(C=C2)O)O)S(=O)(=O)[O-].[Na+]

InChIKey
COEZWFYORILMOM-UHFFFAOYSA-M

InChI

1S/C12H10N2O5S.Na/c15-9-3-6-11(12(16)7-9)14-13-8-1-4-10(5-2-8)20(17,18)19;/h1-7,15-16H,(H,17,18,19);/q;+1/p-1

Synonyms
C.I. Food Yellow 8 | Chrysoin S Specially Pure | Chrysonine S | F9995-1411 | Tropaeolene (Biological Stain) | AKOS004...
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calmagite
CAS: 3147-14-6 Formula: C₁₇H₁₄N₂O₅S Molecular Weight: 358.37

1%

In Stock Item #: C196462

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Technical Identifiers

IUPAC Name

3-hydroxy-4-[(2-hydroxy-5-methylphenyl)diazenyl]naphthalene-1-sulfonic acid

SMILES

CC1=CC(=C(C=C1)O)N=NC2=C(C=C(C3=CC=CC=C32)S(=O)(=O)O)O

InChIKey
VBRNLOQCBCPPHL-UHFFFAOYSA-N

InChI

1S/C17H14N2O5S/c1-10-6-7-14(20)13(8-10)18-19-17-12-5-3-2-4-11(12)16(9-15(17)21)25(22,23)24/h2-9,20-21H,1H3,(H,22,23,24)

Synonyms
3-hydroxy-4-[(2-hydroxy-5-methylphenyl)diazenyl]naphthalene-1-sulfonic acid | CALMAGITE [MI] | 1-Naphthalenesulfonic ...
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Thymolphthalein
CAS: 125-20-2 EC Number: 204-729-7 PubChem CID: 31316 Formula: C₂₈H₃₀O₄ Molecular Weight: 430.54

0.05%

In Stock Item #: T196525

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Technical Identifiers

IUPAC Name

3,3-bis(4-hydroxy-2-methyl-5-propan-2-ylphenyl)-2-benzofuran-1-one

SMILES

CC1=CC(=C(C=C1C2(C3=CC=CC=C3C(=O)O2)C4=CC(=C(C=C4C)O)C(C)C)C(C)C)O

InChIKey
LDKDGDIWEUUXSH-UHFFFAOYSA-N

InChI

1S/C28H30O4/c1-15(2)20-13-23(17(5)11-25(20)29)28(22-10-8-7-9-19(22)27(31)32-28)24-14-21(16(3)4)26(30)12-18(24)6/h7-16,29-30H,1-6H3

Synonyms
1(3H)-Isobenzofuranone,3-bis[4-hydroxy-2-methyl-5-(1-methylethyl)phenyl]- | 3,3-bis(4-hydroxy-2-methyl-5-propan-2-ylp...
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m-Cresol purple indicator
CAS: 2303-01-7 EC Number: 218-960-6 Formula: C₂₁H₁₈O₅S Molecular Weight: 382.43

0.4%

Out of Stock Item #: M196490

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Technical Identifiers

IUPAC Name

4-[3-(4-hydroxy-2-methylphenyl)-1,1-dioxo-2,1λ6-benzoxathiol-3-yl]-3-methylphenol

SMILES

CC1=C(C=CC(=C1)O)C2(C3=CC=CC=C3S(=O)(=O)O2)C4=C(C=C(C=C4)O)C

InChIKey
OLQIKGSZDTXODA-UHFFFAOYSA-N

InChI

1S/C21H18O5S/c1-13-11-15(22)7-9-17(13)21(18-10-8-16(23)12-14(18)2)19-5-3-4-6-20(19)27(24,25)26-21/h3-12,22-23H,1-2H3

Synonyms
m-Cresol purple|2303-01-7|Cresol purple|3,3-Bis(4-hydroxy-2-methylphenyl)-3H-benzo[c][1,2]oxathiole 1,1-dioxide|m-Cre...
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m-Cresol purple indicator
CAS: 2303-01-7 EC Number: 218-960-6 Formula: C₂₁H₁₈O₅S Molecular Weight: 382.43

0.04%(w/v) in water

Out of Stock Item #: M196488

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Technical Identifiers

IUPAC Name

4-[3-(4-hydroxy-2-methylphenyl)-1,1-dioxo-2,1λ6-benzoxathiol-3-yl]-3-methylphenol

SMILES

CC1=C(C=CC(=C1)O)C2(C3=CC=CC=C3S(=O)(=O)O2)C4=C(C=C(C=C4)O)C

InChIKey
OLQIKGSZDTXODA-UHFFFAOYSA-N

InChI

1S/C21H18O5S/c1-13-11-15(22)7-9-17(13)21(18-10-8-16(23)12-14(18)2)19-5-3-4-6-20(19)27(24,25)26-21/h3-12,22-23H,1-2H3

Synonyms
m-Cresol purple|2303-01-7|Cresol purple|3,3-Bis(4-hydroxy-2-methylphenyl)-3H-benzo[c][1,2]oxathiole 1,1-dioxide|m-Cre...

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Frequently Asked Questions

How do I choose between Indicators options?

Match concentration, purity, and form to your application. Higher purity is critical for analytical work, while routine lab use tolerates technical grade. Consider container size and storage requirements.

What specifications matter for Indicators?

Purity grade, concentration (for solutions), water content, certified impurity limits, and packaging type. Check certificate of analysis for batch-specific values.

How should Indicators be safely handled?

Follow standard chemical safety practices: PPE including gloves and eye protection, work in well-ventilated areas, and consult the SDS for specific hazards. Store in chemically compatible containers.

Are pre-prepared and ready-to-use options available?

Yes. Many indicators are stocked as ready-to-use solutions at standard concentrations, eliminating the need for in-house preparation and improving reproducibility.

Indicators support endpoint detection, pH assessment, and visual monitoring in analytical and educational laboratory workflows. Selection generally depends on transition range, color response, solvent compatibility, application format, and whether the indicator is intended for titration, pH work, or a more specialized analysis. Use this category when the workflow benefits from rapid visual readout or classic wet-chemistry methods. It fits naturally alongside pH buffers, titration reagents, and general analytical chemicals.