Skip to main content
. Author manuscript; available in PMC: 2010 May 12.
Published in final edited form as: Anal Chem. 2007 Aug 3;79(17):6775–6782. doi: 10.1021/ac070907g

Table 1.

Spectroscopic Parameters of Fluorescein and 2′,7′-Diethylfluorescein (DEF)

Parameter Fluorescein DEF
pKa 6.30 ± 0.02 6.61 ± 0.03
λmax (nm) 491 501
ε(mM−1cm−1) 89.8 ± 0.4 98.5 ± 0.4
λem (nm) 510 520
Φ 0.95 ± 0.03 13 0.89 ± 0.03