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QXY7 NHS ester [equivalent to QSY-7 NHS ester]

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Physical properties
Molecular weight791.32
Spectral properties
Absorbance (nm)561
Correction Factor (280 nm)0.22
Extinction coefficient (cm -1 M -1)900001
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
Absorbance (nm)
Correction Factor (280 nm)
Extinction coefficient (cm -1 M -1)
QXY7 is the same molecule to QSY-7 acid (ThermoFisher). QXY7 has a broad and intense absorption at ~550 nm maxima with no detectable fluorescence, making it useful as an acceptor in fluorescence resonance energy transfer (FRET) applications paring with Cy3, TAMRA, Alexa Fluor 555 and iFluor 647 or other spectrally similar fluorescent dyes. QXY7 NHS ester is quite stable and readily reacts with amino-containing molecules such as amino-modified oligos, proteins and peptides.


Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of QXY7 NHS ester [equivalent to QSY-7 NHS ester] 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 mM126.371 µL631.856 µL1.264 mL6.319 mL12.637 mL
5 mM25.274 µL126.371 µL252.742 µL1.264 mL2.527 mL
10 mM12.637 µL63.186 µL126.371 µL631.856 µL1.264 mL

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Spectral properties

Absorbance (nm)561
Correction Factor (280 nm)0.22
Extinction coefficient (cm -1 M -1)900001



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