MOPS (3-(N-morpholino)propanesulfonic acid) is a buffer introduced in the 1960s, one of the twenty Good's buffers. It is a structural analog to MES,^[1] and like MES, its structure contains a morpholine ring. HEPES is a similar pH buffering compound that contains a piperazine ring. With a pK_a of 7.20, MOPS is an excellent buffer for many biological systems at near-neutral pH.

Quick Facts Names, Identifiers ...

MOPS

Names
Preferred IUPAC name 3-(Morpholin-4-yl)propane-1-sulfonic acid
Other names 3-(N-Morpholino)propanesulfonic acid, 3-Morpholinopropanesulfonic acid, 3-N-Morpholino propansulfonic acid, 4-Morpholinepropanesulfonic acid
Identifiers
CAS Number	1132-61-2 Y
3D model (JSmol)	Interactive image
ChemSpider	63972 N
ECHA InfoCard	100.013.162
PubChem CID	70807 2723950
UNII	273BP63NV3 Y
CompTox Dashboard (EPA)	DTXSID4044371
InChI InChI=1S/C7H15NO4S/c9-13(10,11)7-1-2-8-3-5-12-6-4-8/h1-7H2,(H,9,10,11) N Key: DVLFYONBTKHTER-UHFFFAOYSA-N N InChI=1/C7H15NO4S/c9-13(10,11)7-1-2-8-3-5-12-6-4-8/h1-7H2,(H,9,10,11) Key: DVLFYONBTKHTER-UHFFFAOYAN
SMILES C1COCCN1CCCS(=O)(=O)O
Properties
Chemical formula	C7H15NO4S
Molar mass	209.26 g·mol−1
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
Safety data sheet (SDS)	MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

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MOPS is frequently used as a buffering agent in biology and biochemistry. It has been tested and recommended for polyacrylamide gel electrophoresis.^[2] Usage above 20 mM in mammalian cell culture work is not recommended.^[3] MOPS buffer solutions become discolored (yellow) over time, but reportedly slight discoloration does not significantly affect the buffering characteristics.^[4]

• CAPS
• HEPPS
• Tris
• Common buffer compounds used in biology