MES monohydrate Buffer

Synonyms: MES or 2-(N-morpholino)ethanesulfonic acid or 4-morpholineethanesulfonic acid monohydrate
C₆H₁₃NO₄S • H₂O
M_r 213.25
CAS Number [145224-94-8]
EC Number 224-632-3
Beilstein Registry Number 329824236
RTECS QE3479500
MDL Number MFCD00149409
Purity ≥ 99.5%
pKa 6.1 at 25°C

Solutions are stable at 2-8°C for months. Autoclaving is not recommended for any sulfonic acid buffer. When MES solutions are autoclaved, they turn yellow (although pH does not change measurably). The identity of the yellow breakdown product is unknown. When MES solutions are stored at room temperature, they can turn yellow within six months.

Useful pH range of MES 5.2 - 7.1

Titrate HR2-587 to the desired pH using NaOH
HR2-587 Measured pH Range: 3.2 - 3.4 at 25°C
HR2-587 Measured Conductivity Range: 166.4 - 2440 µS/cm at 25°C
HR2-587 Measured Refractive Index Range: 1.34655 - 1.34731 at 20°C

HR2-787 has been titrated to pH 6.5 using NaOH
HR2-787 Measured Conductivity Range: 19.2 - 25.6 mS/cm at 25°C
HR2-787 Measured Refractive Index Range: 1.36113 - 1.36251 at 20°C

HR2-943-07 - MES monohydrate pH 5.8 - 1.0 M solution is a Custom Shop reagent and is used to reproduce and optimize Crystallization Reagents for use with the Silver Bullets kit.

Impurities:
Endotoxin ≤ 50 EU/g
Yeast and Mold ≤ 100 CFU/g
Bioburden ≤ 100 CFU/g
Al ≤ 5.0 ppm
As ≤ 3.0 ppm
Ba ≤ 5.0 ppm
Bi ≤ 5.0 ppm
Ca ≤ 20.0 ppm
Cd ≤ 5.0 ppm
Co ≤ 5.0 ppm
Cr ≤ 5.0 ppm
Cu ≤ 5.0 ppm
Fe ≤ 5.0 ppm
Li ≤ 5.0 ppm
Mg ≤ 5.0 ppm
Mn ≤ 5.0 ppm
Mo ≤ 5.0 ppm
Na ≤ 20.0 ppm
Ni ≤ 5.0 ppm
Pb ≤ 5.0 ppm
Sb ≤ 5.0 ppm
Zn ≤ 5.0 ppm