Synonym(s): 2-(4-morpholino)ethanesulfonic acid, 2-morpholinoethanesulfonic acid, Morpholine-4-ethanesulfonic acid hydrate, 2-(N-Morpholino)ethanesulfonic acid, 4-Morpholineethanesulfonic acid monohydrate

Description

MES monohydrate is a buffering agent used in biochemistry and molecular biology that was selected and described by Good et al. It is a zwitterionic, morpholinic buffer that is useful for a pH range of 5.5 – 6.7 and commonly used for cell culture media, as a running buffer in electrophoresis, and for protein purification in chromatography. MES lacks the ability to form a complex with most metal ions and is recommended for use as a non-coordinating buffer in solutions with metal ions. MES is often used in buffered culture media for bacteria, yeast, and mammalian cells. It is toxic towards plants at high concentrations, but can be used in culture media at lower concentrations for plants. Due to low ionic mobility, MES is regarded as an excellent buffer for use in capillary electrochromatography. MES is often employed as a substitute for the highly toxic cacodylate, as well as a substitute for the non-zwitterionic buffers citrate and malate. MES complexes with some organotin(IV) molecules that are being explored as antitumor agents.

MES free acid or MES free acid monohydrate can be mixed with MES sodium salt to acquire desired pH. Alternatively, MES free acid or MES free acid monohydrate can be titrated with sodium hydroxide to attain desired pH.

Specifications

Item	Value
Chemical Name	2-Morpholinoethanesulfonic Acid Monohydrate
Appearance	Pure White Powder
CAS No.	145224-94-8
Molecular Formula	C₆H₁₃NO₄S·H₂O
Molecular Weight	213.3
Grade	Biochemical Grade
Purity	≥99%
pKa at 20°C	6.05-6.25
Solubility	Clear
pH (1.0% Aqueous Solution, 26°C)	2.5-4.0
Heavy Metals	≤10PPM
Sulfates	≤100PPM
Iron	≤10PPM
Chlorides	≤100PPM
Loss on Drying	7-10%
UV Absorbance	≤0.05Abs Unit
Storage / Handling	Store at Room Temperature.

Features

Optimal buffering range for biological systems（pH 5.5–6.7）

MES is a zwitterionic Good’s buffer with a pKa around 6.1, providing highly stable buffering capacity in mildly acidic to near-neutral ranges, ideal for biochemical and cell-based workflows.
High-purity biochemical grade (≥99%) with low contaminants

Strict control of heavy metals, sulfate, iron, and chloride ions ensures compatibility with sensitive molecular biology, protein work, and cell culture assays.
Minimal metal-ion interaction & low UV absorbance

MES does not significantly chelate metal ions such as Ca²⁺, Mg²⁺, or transition metals, making it suitable for systems requiring metal cofactors. Its very low UV absorbance is beneficial for UV-monitoring assays and chromatography.
Excellent water solubility & temperature-stable performance

This buffer dissolves easily in aqueous solutions and maintains stable pKa over typical laboratory temperature ranges, supporting reproducible results across experiments.
Flexible preparation in free-acid or sodium-salt forms

The monohydrate form can be titrated directly with NaOH or mixed with MES sodium salt to prepare buffers at precise pH values without introducing unwanted ions.

Applications

Cell culture media buffering

Widely used in bacterial, yeast, and mammalian cell media to maintain stable pH environments and improve experimental consistency.
Protein purification and chromatography

Ideal for ion-exchange, affinity, or FPLC workflows, especially where metal-ion interference must be minimized.
Electrophoresis and gel-based separations

Commonly formulated as a running buffer for PAGE and bis-tris gel systems, offering stable pH during protein or nucleic acid migration.
Biochemical and enzymatic assays

Suitable for enzyme reactions, diagnostic reagent formulation, and pH-controlled biochemical experiments requiring low UV background.
Analytical techniques such as capillary electrophoresis

Its low ionic mobility and controlled conductivity make MES particularly useful in capillary electrochromatography, microfluidics, and precision analytical systems.

Safety Disclaimer

This product is intended for laboratory research use only. Not for drug, human, or veterinary use. Review the Safety Data Sheet (SDS) provided by BioFargo for detailed handling, storage, hazard, and disposal information. Use appropriate personal protective equipment (PPE) including gloves, lab coat, and eye protection when handling. Dispose of waste and residual buffer in accordance with local, state, and federal regulations. Ensure proper ventilation if preparing large volumes or heating solutions.

Documents

SDS

MES.H2O 99% Biochemical Grade