Fluorescein 5(6)-isothiocyanate
Fluorescein 5(6)-isothiocyanate (CAS: 27072-45-3), with the molecular formula C21H11NO5S and a molecular weight of 389.38 g/mol, is a vital fluorescent labelling reagent. This compound is primarily utilised for the fluorescent labelling of proteins, including its application in immunofluorescence techniques and protein labelling for gel chromatography. It is an indispensable tool for researchers in biochemistry and molecular biology requiring precise cellular and molecular detection.
- IUPAC
- FITC,Fluorescein isothiocyanate
- Synonyms
- FITCFluorescein isothiocyanate

Protein Fluorescent Labelling
Used for the fluorescent labelling of proteins, enabling their detection and visualisation in various biological assays, such as immunofluorescence.
Gel Chromatography
Suitable for labelling proteins destined for gel chromatography, aiding in their separation and analysis based on size and other properties.
Biochemical Research
Serves as a key reagent in biochemical research for assays requiring fluorescent detection and tracking of biomolecules.
| Molecular weight | 389.38 |
|---|---|
| Empirical formula | C21H11NO5S |
| Assay | ≥90% (HPLC) |
| Storage temperature | 2-8°C |
| Application | For fluorescent labeling of proteins (e.g. immunofluorescence); H Protein labeling for gel chromatography |

Hazard statements
- H334May cause allergy or asthma symptoms if inhaled
Precautionary statements
- P261Avoid breathing dust, fume, gas or vapours
- P342
| Protective equipment | dust mask type N95 (US), Eyeshields, Faceshields, Gloves |
|---|---|
| Water hazard class (WGK, DE) | 3 |
| Hazard codes (EU) | Xn |
| Risk statements (R) | 42 |
| Safety statements (S) | 22-24/25 |
Hazard information is provided for guidance. Always consult the product Safety Data Sheet (SDS), available on request, before handling.
| Product Line | BioReagent |
|---|
Documentation
Every batch ships with a Certificate of Analysis covering assay, identity and purity; the grade is confirmed against your enquiry. Safety Data Sheets and technical data sheets are available on request.
Supply & logistics
Samples for technical evaluation; bulk MOQ by grade and packaging. In-stock material ships in 7–10 working days, worldwide, with full export documentation.
What is Fluorescein 5(6)-isothiocyanate used for?
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Fluorescein 5(6)-isothiocyanate is used for the fluorescent labelling of proteins, including applications in immunofluorescence and protein labelling for gel chromatography.
What is the CAS number and formula for Fluorescein 5(6)-isothiocyanate?
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The CAS number is 27072-45-3 and the molecular formula is C21H11NO5S.
What grade and purity does Tech Serve Solutions supply?
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Tech Serve Solutions supplies Fluorescein 5(6)-isothiocyanate with an assay of ≥90% (HPLC). This product is not supplied as USP, BP, or EP grade.
What are the safety precautions for handling Fluorescein 5(6)-isothiocyanate?
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This compound is classified as dangerous. Inhalation of dust may cause allergy or asthma symptoms or breathing difficulties (H334). Ensure appropriate personal protective equipment, including a dust mask type N95 (US), eyeshields, face shields, and gloves, is used. Handle in a well-ventilated area and avoid dust formation. Always consult the Safety Data Sheet (SDS) before use.
How is Fluorescein 5(6)-isothiocyanate shipped and stored?
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Fluorescein 5(6)-isothiocyanate is exported globally by TSS and should be stored at 2-8°C to maintain its integrity.
How can I request a sample or quote for Fluorescein 5(6)-isothiocyanate?
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To request a sample or quote, please contact our sales team through the website or by calling us directly. We aim to respond promptly to all inquiries.
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