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Fluorescein isothiocyanate isomer I

Also known as: Fluorescein 5-isothiocyanate, 5-FITC, FITC isomer I, 5-Isothiocyanatofluorescein, 2-(6-Hydroxy-3-oxo-3H-xanthen-9-yl)-5-isothiocyanatobenzoic acid, 3',6'-Dihydroxy-5-isothiocyanato-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one

Fluorescein isothiocyanate isomer I (CAS 3326-32-7) is a compound in the Organic Acids category listed in the Jingsj chemical database. It has the molecular formula C21H11NO5S and a molecular weight of 389.381 g/mol. Key properties include a melting point of >360 °C(lit.), a boiling point of 708.6±60.0 °C at 760 mmHg, a density of 1.5±0.1 g/cm3 and a flash point of 382.4±32.9 °C. It is classified under GHS with signal word Danger and hazard statements H317 — May cause an allergic skin reaction and H334 — May cause allergy or asthma symptoms if inhaled. It is listed by 1 supplier, from 1.26 to 1,090.00 CNY. Record last updated Nov 3, 2026.

CAS No.
3326-32-7
Jingsj CID
J-6169-2
Molecular Formula
C21H11NO5S
Molecular Weight
389.381 g/mol
Category
Organic Acids
Last updated
11/3/2026
In Stock

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In Stock
90%
500mg
¥630.00
$0.19 /mgBest
¥1.26/mg CNY
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MOQ 500mg
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100mg
¥168.00
$0.25 /mg
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50mg
¥240.00
$0.72 /mg
¥4.80/mg CNY
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MOQ 50mg

Physicochemical Properties

Melting Point>360 °C(lit.)
Boiling Point708.6±60.0 °C at 760 mmHg
Density1.5±0.1 g/cm3
Flash Point382.4±32.9 °C
Exact Mass389.035797
PSA120.44000
LogP4.00
Vapor Pressure0.0±2.3 mmHg at 25°C
Refractive Index1.754
Additional Propertypractically insoluble

GHS Safety & Compliance

Health HazardSignal word: Danger
  • H317 — May cause an allergic skin reaction
  • H334 — May cause allergy or asthma symptoms if inhaled

Activity & Biological Data

Additional Information[1]. Gao SG, et al. Phosphorylation of osteopontin has proapoptotic and proinflammatory effects on human knee osteoarthritis chondrocytes. Exp Ther Med. 2016 Nov;12(5):3488-3494. Epub 2016 Oct 5. [2]. Zhu X, et al. Ratiometric, visual, dual-signal fluorescent sensing and imaging of pH/copper ions in real samples based on carbon dots-fluorescein isothiocyanate composites. Talanta. 2017 Jan 1;162:65-71

Frequently Asked Questions

What is the CAS number of Fluorescein isothiocyanate isomer I?

The CAS number of Fluorescein isothiocyanate isomer I is 3326-32-7.

What are the molecular formula and molecular weight of Fluorescein isothiocyanate isomer I?

Fluorescein isothiocyanate isomer I has molecular formula C21H11NO5S and molecular weight 389.381 g/mol.

Which suppliers offer Fluorescein isothiocyanate isomer I?

1 supplier(s) listed; reference unit price ¥1.26–1090.00 /mg.

Is Fluorescein isothiocyanate isomer I hazardous?

Fluorescein isothiocyanate isomer I has GHS signal word Danger and hazard statements H317 — May cause an allergic skin reaction; H334 — May cause allergy or asthma symptoms if inhaled.

What are the upstream and downstream products of Fluorescein isothiocyanate isomer I?

For Fluorescein isothiocyanate isomer I, Upstream Products: Fluorescein, Thiophosgene, 5-Aminofluorescein.

Data compiled from public chemical databases such as PubChem and supplier catalogs; supplier offers are provided by suppliers.

Last updated:

How to cite: Jingsj. "Fluorescein isothiocyanate isomer I (CAS 3326-32-7)". Jingsj Chemical Database. https://www.jingsj.com/compound/J-6169-2 (accessed 2026-11-06).

Data for reference only; verify product details with suppliers before purchase.