Description
5-FAM – High-Purity Fluorescein Dye for Reliable Biomolecule Labeling
5-Carboxyfluorescein (5-FAM) is a high-purity, non-activated single-isomer fluorescein dye ideal for covalent labeling of proteins and alkylamino-modified nucleic acids. With its strong absorption near the 488 nm argon-ion laser line, 5-FAM is a preferred fluorophore in confocal laser scanning microscopy and flow cytometry. Its high fluorescence quantum yield, excellent water solubility, and low precipitation tendency make it a robust and versatile tool for a wide range of fluorescence-based applications.
Performance Highlights
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High-purity, non-activated fluorescein dye (≥99%)
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Excitation/emission maxima: 493 nm / 517 nm at pH > 8
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Strong absorption (ε > 72,000 M⁻¹·cm⁻¹)
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Excellent fluorescence quantum yield and solubility
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Ideal for bioconjugation, microscopy, and FACS
Properties
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Molecular Weight: 376.32
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Empirical Formula: C₂₁H₁₂O₇
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CAS Number: 76823-03-5
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Absorption [λmax]: 493 ± 3 nm
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Emission [λmax]: 517 ± 3 nm
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Extinction Coefficient (ε): >72,000 M⁻¹·cm⁻¹
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Excitation Source: 488 nm (argon-ion laser)
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Reactive Moiety: Free carboxylic acid
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Solubility: Methanol, DMF, DMSO
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Buffer System for Fluorescence Readings: PBS, pH 7.4
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Appearance: Yellow solid (powder)
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Storage: Room temperature; keep dry and protected from light (especially in solution)
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Trade Name: 5-Carboxyfluorescein; 5-FAM
Application
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Bioconjugation of proteins and oligonucleotides
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Confocal laser scanning microscopy
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Flow cytometry (FACS)
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Diagnostic fluorescence assays and imaging techniques
