Fluorescein CAS 2321-07-5

Factory Supply Fluorescein CAS 2321-07-5 with Best Price

  • Appearance: Orange or light orange-red crystalline powder
  • Purity: 99. 0%min
  • Stock: In stock
  • Sample: Available
  • Zhishang Chemical: Fluorescein Supplier & Manufacturer

Basic Info

What is Fluorescein?

Fluorescein is a synthetic organic compound that appears as a dark orange/red powder and is slightly soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications.

Fluorescein is a fluorescent group commonly used in microscopes, dye lasers as gain media, forensic and serological detection of potential blood stains, and dye tracing. The maximum absorption wavelength of fluorescein is 494 nm, and the maximum emission wavelength is 521 nm (in water). The main derivatives are fluorescein isothiocyanate (FITC) and 6-FAM phosphorous amide in oligonucleotide synthesis.

Fluorescein also has an equal absorbance point at 460 nm (all pH values absorb the same). Fluorescein is also known as a color additive (D&C Yellow No. 7). The disodium salt form of fluorescein is called uranium or D&C yellow.

The color of its aqueous solution changes from green to orange depending on the observation method: through reflection or transmission, as observed in a bubble level, where fluorescein is added as a colorant to the alcohol filled with alcohol. Tube to increase the visibility of bubbles and the accuracy of the instrument. A more concentrated solution of fluorescein may even appear red.

Fluorescein Uses

  1. Fluorescein is an intermediate of merbromine red, which can be used as a fluorescence analysis reagent to determine chlorine, bromine, iodine, and sulfur ions; Oxidation-reduction indicator reagent; Biological staining agents.
  2. Fluorescein (Resorcinol phthalein) is a synthetic organic photosensitive dye compound. Fluorescein is a fluorescent tracer that can be applied to medicine, biology, and tissues infected with tumors.
  3. A fluorescent tracer used for various applications. It is used as a tool in ophthalmology to diagnose corneal abrasions, corneal ulcers, and herpetic corneal infections. It can attach to certain biologically active molecules, allowing biologists to target fluorescent groups to specific proteins or structures within cells.
  4.  Fluorescein is used as a fluorescent tracer in many applications, including as a gain medium in dye lasers, detecting potential blood stains in forensic and serology, and in dye tracing. It is used to locate multiple muscular ventricular septal defects and confirm the presence of any residual defects during open heart surgery. Apply it to the teeth to expose dental plaque.

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This is William, CEO of Zhishang Chemical Co., Ltd.

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Several Commonly Used Fluoresceins and their Basic Biological Properties

Application of Fluorescein

  • Biochemical research
    In cell biology, isothiocyanate derivatives of fluorescein are commonly used for labeling and tracking cells in fluorescence microscopy applications such as flow cytometry. Other biologically active molecules (such as antibodies) can also attach to fluorescein, enabling biologists to target specific proteins or structures within cells with fluorescent groups. This application is common in yeast display.
  • Healthcare Applications
    Sodium fluorescein “is a sodium salt of fluorescein, widely used as a diagnostic tool in ophthalmology and optometry, with local fluorescein used for the diagnosis of corneal abrasions, corneal ulcers, and herpetic corneal infections. It is also used in the fitting of hard breathable contact lenses to evaluate the tear layer below the lens.
  • Application in river systems
    In 1966, environmentalists forced the use of plant dyes to protect local wildlife. Other uses of fluorescein include adding it as a water-soluble dye to rainwater in environmental testing simulations to help locate and analyze any leaks, as well as using it as a methylated alcohol dye in Australia and New Zealand.
  • Oilfield Applications
    Fluorescein dye solution (usually with an active ingredient of 15%) is commonly used as an auxiliary means for leak detection during hydrostatic testing of subsea oil and gas pipelines and other subsea infrastructure. Divers carrying ultraviolet lights can detect leaks.


  1. Noga E. J., Udomkusonsri, P. (2002). “Fluorescein: A Rapid, Sensitive, Nonlethal Method for Detecting Skin Ulceration in Fish” (PDF)
  2. Sjöback, Robert; Nygren, Jan; Kubista, Mikael (1995-06-01). “Absorption and fluorescence properties of fluorescein”Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy.

Fluorescein Supplier and Manufacturer

As a fluorescein supplier and manufacturer with a strict standard product quality system certificate, Zhishang Chemical has long been providing the best fluorescein raw materials to customers all over the world.

Over the years, relying on professional team experience and customer-centric team concept to meet customer needs in a timely manner, our company enjoys a high reputation in the world. At present, our company has served more than 6,000 customers and has established long-term cooperative relations with customers from many countries.

If you have a demand for fluorescein and related products, please contact our service staff Zhishang Chemical – White directly, and we will provide you with high-quality products at the best price.

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