M5287 Sigma-Aldrich

MES hydrate

≥99.5% (titration), pH 2.5-4.0 (0.5 M in H2O), BioXtra

Synonym: 2-(N-Morpholino)ethanesulfonic acid hydrate, 4-Morpholineethanesulfonic acid

  • CAS Number 1266615-59-1

  • Empirical Formula (Hill Notation) C6H13NO4S · xH2O

  • Molecular Weight 195.24 (anhydrous basis)

  •  MDL number MFCD00149409

  •  eCl@ss 32129211

  •  PubChem Substance ID 329818007

  •  NACRES NA.25



Related Categories BioXtra Buffers, Biochemicals and Reagents, Biological Buffers, Buffers A to Z, Good’s Buffers More...
Quality Level   400
product line   BioXtra
assay   ≥99.5% (titration)
form   crystalline powder
impurities   Insoluble matter, passes filter test
ign. residue (900°C)   ≤0.05%
pH   2.5-4.0 (0.5 M in H2O)
useful pH range   5.5 - 6.7
pKa    6.1
solubility   H2O: 0.5 M, clear, colorless
anion traces   chloride (Cl-): ≤0.005%
cation traces   Al: ≤0.0005%
  As: ≤0.0001%
  Ba: ≤0.0005%
  Bi: ≤0.0005%
  Ca: ≤0.002%
  Cd: ≤0.0005%
  Co: ≤0.0005%
  Cr: ≤0.0005%
  Cu: ≤0.0005%
  Fe: ≤0.0005%
  K: ≤0.005%
  Li: ≤0.0005%
  Mg: ≤0.0005%
  Mn: ≤0.0005%
  Mo: ≤0.0005%
  Na: ≤0.005%
  Ni: ≤0.0005%
  Pb: ≤0.0005%
  Sr: ≤0.0005%
  Zn: ≤0.0005%
absorption   ≤0.020 at 280 in H2O at 0.5 M
  ≤0.025 at 260 in H2O at 0.5 M
storage temp.   room temp
SMILES string   O.OS(=O)(=O)CCN1CCOCC1
InChI   1S/C6H13NO4S.H2O/c8-12(9,10)6-3-7-1-4-11-5-2-7;/h1-6H2,(H,8,9,10);1H2


General description

MES is one of the Good′s buffers, the most extensively used biological buffers. MES is a zwitterionic N-substituted aminosulfonic acid with a morpholinic ring. It does not form complexes with majority of the metals used in environmental and biological studies. It is easily soluble in water and has minimum lipid solubility, making it impermeable to membranes.


MES Hydrate has been used:
• As a component of extraction buffer in the extraction of the enzyme BACE1
• As a component of the reaction mixture for the measurement of 5,10-methenyltetrahydrofolate synthetase (MTHFS) enzyme activity in fibroblasts
• As a component of MES coupling buffer during the coupling of mAb or GST-fusion proteins to carboxylate-modified polystyrene latex (CML) beads


50, 250 g in poly bottle

Preparation Note

A buffer using MES can be prepared by titrating with NaOH to the desired pH. Alternatively, stock solutions of MES and MES sodium salt can be mixed to attain the desired pH. Standard mixing tables using stock solutions to prepare buffers of a given pH have been published. MES is not recommended for buffering at pH 7.4; other buffers should be considered.

Storage and Stability

Solutions are stable at 2-8 C for months. Sterilize by filtration through 0.2uM filters. Autoclaving is not recommended for any sulfonic acid buffer. If buffers must be nuclease-free, treat the water first, and then add the buffer after autoclaving. When MES solutions are autoclaved, they turn yellow (although pH does not change measurably). The identity of the yellow breakdown product is unknown.

Other Notes

Easily compare specifications for MES products with the MES specification table.

Solubility: MES is soluble in water, giving a clear colourless solution at concentrations of 0.5M or higher. Similar product MES hydrate M8250 is tested at 20g/80mL water, or 1.3M. The pH of a solution should be between 2.5 and 5, depending on the concentration. A saturated solution at 0°C is approximately 0.65M.

Safety & Documentation

Safety Information

Personal Protective Equipment 
NONH for all modes of transport
WGK Germany 
Flash Point(F) 
Not applicable
Flash Point(C) 
Not applicable


Certificate of Analysis (COA)

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Certificate of Origin (COO)

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Protocols & Articles

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