The tetra-chloro derivative of fluorescein, Tetrachloro fluorescein (TET), can be used for the modification of oligonucleotides with fluorophore.  TET has an absorbance maximum of 521 nm and an emission maximum of 536 nm.  TET dye is useful in real-time PCR, being used as a reporter moiety in TaqMan probes, Scorpion primers, and Molecular Beacons (1,2,3).  For the above applications, TET dye is commonly paired with the dark quencher BHQ-1, as they exhibit excellent spectral overlap.  TET-labeled oligonucleotides (DNA) as hybridization probes are useful for various in vivo and in vitro research/diagnostic applications, and for structure-function studies of DNA, RNA, and protein-oligonucleotide complexes.  Oligonucleotides labeled with TET dye at 5-end can be used to generate fluorescently-labeled PCR products, as primers for DNA sequencing, or for genetic analysis (AFLP or microsatellite).


1. Livak, K.J., Flood, S.J.A., Marmaro, J., Giusti, W., Deetz, K. Oligonucleotides with fluorescent dyes at opposite ends provide a quenched probe system useful for detecting PCR product and nucleic acid hybridization.PCR Methods Appl. (1995), 4: 1-6.

 2. Thelwell, N., Millington, S., Solinas, A., Booth, J., Brown, T. Mode of action and application of Scorpion primers to mutation detection.  Nucleic Acids Res. (2000), 28: 3752-3761.

 3. Tyagi, S., Kramer, F.R. Molecular beacons: probes that fluoresce upon hybridization. Nat. Biotechnol. (1996), 14: 303-308.

Product Information


Product Name:

TET, Tetrachlorofulorescein Oligonucleotide Labeling

Alternate Name:



Fluorescent dye Label

Modification Code:


Chemical Formula:


Exact Mass:


Formula Weight:


Absorption λmax:

521 nm

Emission (nm):

536 nm

Extinction Coefficient, ε(λ):



Bio-Synthesis Inc. Oligo Structure



Delivery Format:


Shipping Conditions:

Room Temperature

Storage Conditions:

-20°C To -70°C
Oligonucleotides are stable in solution at 4°C for up to 2 weeks. Properly reconstituted material stored at -20°C should be stable for at least 6 months. Dried DNA (when kept at -20°C) in a nuclease-free environment should be stable for years.