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FAM-xtra™ Phosphoramidite

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Physical properties
Molecular weight879.94
Spectral properties
Correction Factor (260 nm)0.32
Correction Factor (280 nm)0.178
Extinction coefficient (cm -1 M -1)83000
Excitation (nm)493
Emission (nm)517
Storage, safety and handling
H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22
StorageFreeze (< -15 °C); Minimize light exposure


Molecular weight
Correction Factor (260 nm)
Correction Factor (280 nm)
Extinction coefficient (cm -1 M -1)
Excitation (nm)
Emission (nm)
There are several ways of labeling an oligonucleotide with fluorescein. 6-FAM phosphoramidite might be the most popular fluorescent building block that is widely used to efficiently label an oligonucleotide at the 5’-end with the fluorescein fluorophore. Standard cleavage and deprotection with ammonium hydroxide are used to liberate the fluorescein-labeled oligos. Although 6-FAM has be ubiquitously used for developing a variety of qPCR probes, its fluorescence suffers two serve limitations: a). highly pH dependent; and b). photo-bleach rapidly. FAM-xtra™ Phosphoramidite has been developed to address these two limitations while the well-beloved operational convenience of 6-FAM phosphoramidite is intactly maintained. FAM-xtra Phosphoramidite can be used exactly as is used for 6-FAM phosphoramidite under the same operation conditions without any changes needed. The oligos made from FAM-xtra Phosphoramidite have quite a few great benefits: a). FAM-xtra-labeled oligos have the identical spectra to those of 6-FAM labeled ones; b). FAM-xtra-labeled oligos are much brighter than the corresponding FAM-labeled ones; c). FAM-xtra-labeled oligos have much higher photostability than the corresponding FAM-labeled ones; and d). The fluorescence of FAM-xtra-labeled oligos is much less pH sensitive than that of the corresponding FAM-labeled ones. Under the physiological conditions, the fluorescence of FAM-xtra-labeled oligos is essentially pH-independent, making the FAM-xtra-labeled oligos much more robust qPCR probes.


Common stock solution preparation

Table 1. Volume of MeCN needed to reconstitute specific mass of FAM-xtra™ Phosphoramidite to given concentration. Note that volume is only for preparing stock solution. Refer to sample experimental protocol for appropriate experimental/physiological buffers.

0.1 mg0.5 mg1 mg5 mg10 mg
1 mM113.644 µL568.221 µL1.136 mL5.682 mL11.364 mL
5 mM22.729 µL113.644 µL227.288 µL1.136 mL2.273 mL
10 mM11.364 µL56.822 µL113.644 µL568.221 µL1.136 mL

Molarity calculator

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Spectral properties

Correction Factor (260 nm)0.32
Correction Factor (280 nm)0.178
Extinction coefficient (cm -1 M -1)83000
Excitation (nm)493
Emission (nm)517

Product Family

NameExcitation (nm)Emission (nm)Extinction coefficient (cm -1 M -1)Correction Factor (260 nm)Correction Factor (280 nm)
FAM-xtra CPG *500A*493517830000.320.178
FAM-xtra CPG *1000A*493517830000.320.178
6-FAM phosphoramidite [5'-Fluorescein phosphoramidite] *CAS 204697-37-0*493517830000.320.178



View all 8 references: Citation Explorer
Development of an Innovative Intradermal siRNA Delivery System Using a Combination of a Functional Stearylated Cytoplasm-Responsive Peptide and a Tight Junction-Opening Peptide.
Authors: Ibaraki, Hisako and Kanazawa, Takanori and Takashima, Yuuki and Okada, Hiroaki and Seta, Yasuo
Journal: Molecules (Basel, Switzerland) (2016)
Non-nucleoside phosphoramidites of xanthene dyes (FAM, JOE, and TAMRA) for oligonucleotide labeling.
Authors: Kvach, Maksim V and Tsybulsky, Dmitry A and Shmanai, Vadim V and Prokhorenko, Igor A and Stepanova, Irina A and Korshun, Vladimir A
Journal: Current protocols in nucleic acid chemistry (2013): Unit 4.55
Practical synthesis of isomerically pure 5- and 6-carboxytetramethylrhodamines, useful dyes for DNA probes.
Authors: Kvach, Maksim V and Stepanova, Irina A and Prokhorenko, Igor A and Stupak, Aleksander P and Bolibrukh, Dmitry A and Korshun, Vladimir A and Shmanai, Vadim V
Journal: Bioconjugate chemistry (2009): 1673-82
Synthesis and cellular uptake of fluorescently labeled multivalent hyaluronan disaccharide conjugates of oligonucleotide phosphorothioates.
Authors: Karskela, Marika and Virta, Pasi and Malinen, Melina and Urtti, Arto and Lönnberg, Harri
Journal: Bioconjugate chemistry (2008): 2549-58
Synthesis of HyBeacons and dual-labelled probes containing 2'-fluorescent groups for use in genetic analysis.
Authors: Dobson, Neil and McDowell, David G and French, David J and Brown, Lynda J and Mellor, John M and Brown, Tom
Journal: Chemical communications (Cambridge, England) (2003): 1234-5
Amplified fragment length polymorphism (AFLP) protocol for genotyping the malarial parasite Plasmodium falciparum.
Authors: Rubio, J M and Berzosa, P J and Benito, A
Journal: Parasitology (2001): 331-6
Recovery of an oligonucleotide using silver ions immobilized onto paramagnetic particles.
Authors: Ramírez-Vick, J E and García, A A and Lee, J
Journal: Preparative biochemistry & biotechnology (1998): 243-60
Fluorescent dye phosphoramidite labelling of oligonucleotides.
Authors: Theisen, P and McCollum, C and Andrus, A
Journal: Nucleic acids symposium series (1992): 99-100