Synonym: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
Molecular Weight: 238.3
Molecular Formula: C8H18N2O4S
CAS number: 7365-45-9
HEPES is a zwitterionic organic buffering agent. It
is stable, water soluble and does not react with
divalent cations. It has a pKa of 7.5 at 37ºC and
offers an optimal buffering range of pH 6.8 - 8.2. It
maintains the physiological pH despite changes in the
carbondioxide concentrations which take place due to
cellular metabolism.
HEPES is widely used in cell culture media to maintain
the pH levels of basal media. Unlike the bicarbonate
buffers which require CO2, HEPES containing media do
not need CO2 atmosphere for buffering. HEPES is better
than bicarbonate buffer in controlling the pH of the media
in cell culture.
HEPES is generally used at a concentration of 10mM
to 25mM for cell culture application. After addition of
HEPES the pH of the media is adjusted with NaOH
or HCl. It is also necessary to maintain the appropriate
osmolality in the medium. Concentrations of 50mM and
above can be toxic to the cells and are not recommended.
pKa at (20°C) = 7.55
pKa at (37°C) = 7.31
DpKa/°C = -0.014
TCL021 is 1M HEPES solution prepared in sterile tissue
culture grade water.