HEPES

Names
Preferred IUPAC name

2-[4-(2-Hydroxyethyl)piperazin-1-yl]ethane-1-sulfonic acid

Other names

HEPES

Identifiers

CAS Number

* 7365-45-9 Y

3D model (JSmol)

* Interactive image

Beilstein Reference

| 883043
ChEBI |

* CHEBI:42334 Y

ChemSpider |

* 22278 Y

EC Number |

* 230-907-9

PubChem CID

* 23831

RTECS number |

* TL6809000

UNII |

* RWW266YE9I Y

InChI

* InChI=1S/C8H18N2O4S/c11-7-5-9-1-3-10(4-2-9)6-8-15(12,13)14/h11H,1-8H2,(H,12,13,14) Y

Key: JKMHFZQWWAIEOD-UHFFFAOYSA-N Y

* InChI=1/C8H18N2O4S/c11-7-5-9-1-3-10(4-2-9)6-8-15(12,13)14/h11H,1-8H2,(H,12,13,14)

Key: JKMHFZQWWAIEOD-UHFFFAOYAC

SMILES

* OCCN1CC[NH+](CCS(=O)([O-])=O)CC1

Properties

Chemical formula

| C8H18N2O4S
Molar mass | 238.3012 g/mol
Appearance  | white crystalline powder
Density | Not applicable
Melting point | >234-238°C (453-457K)

Solubility in water

| 40 g/100 ml (20°C)
Acidity (pKa)  | 3 (pKa1),
7.5 (pKa2)[1]
Hazards
Main hazards | Eye Irritant
Safety data sheet | [1]
GHS pictograms |
GHS Signal word | Warning

GHS hazard statements

| H315, H319, H335

GHS precautionary statements

| P261, P264, P270, P271, P280, P301+312, P302+352, P304+312, P304+340, P305+351+338, P312, P321, P322, P330, P332+313, P337+313, P362, P363, P403+233, P405, P501
NFPA 704 (fire diamond)  |

Flash point | Non-flammable

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

HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) is a zwitterionic sulfonic acid buffering agent; one of the twenty Good's buffers. HEPES is widely used in cell culture, largely because it is better at maintaining physiological pH despite changes in carbon dioxide concentration (produced by aerobic respiration) when compared to bicarbonate buffers, which are also commonly used in cell culture. [2] Lepe-Zuniga et al. reported an unwanted photochemical process wherein HEPES catalyzes a reaction with riboflavin when exposed to ambient light to produce hydrogen peroxide.[3][4] This is not a problem in bicarbonate-based cell culture buffers. It is therefore strongly advised to keep solutions containing both HEPES and riboflavin in darkness as much as possible to prevent oxidation.

HEPES has the following characteristics:

* pKa1 (25 °C) = 3
* pKa2 (25 °C) = 7.5
* Useful pH range = 2.5 to 3.5 or 6.8 to 8.2

HEPES has negligible metal ion binding,[5] making it a good choice as a buffer for enzymes which might be inhibited by metal chelation.

## See also

* CAPS
* CHES
* MOPS
* HEPPS
* MES
* HEPBS
* PIPES
* Common buffer compounds used in biology

## References

1. ↑ "Phase Coexistence in Single-Lipid Membranes Induced by Buffering Agents". Langmuir 30 (33): 9880-9885. 2014. doi:10.1021/la5018938.
2. ↑ "Acid-base buffering in organ preservation solutions as a function of temperature: new parameters for comparing buffer capacity and efficiency". Cryobiology 45 (1): 33–48. 2002. doi:10.1016/S0011-2240(02)00104-9. PMID 12445548.
3. ↑ "Toxicity of light-exposed Hepes media". Journal of Immunological Methods 103 (1): 145. October 1987. doi:10.1016/0022-1759(87)90253-5. PMID 3655381. http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@rn+7722-84-1.
4. ↑ "Analysis of the cytotoxic effects of light-exposed HEPES-containing culture medium". In Vitro Cellular & Developmental Biology 21 (5): 282–7. May 1985. doi:10.1007/BF02620943. PMID 4019356. http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@rn+7722-84-1.
5. ↑ "Hopax Fine Chemicals - Biological buffers and their interactions with metal ions". https://www.hopaxfc.com/en/blog/biological-buffers-and-their-interactions-with-metal-ions.

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*[CID]: Compound ID
*[H315]: Causes skin irritation
*[H319]: Causes serious eye irritation
*[H335]: May cause respiratory irritation
*[P261]: Avoid breathing dust/fume/gas/mist/vapours/spray
*[P264]: Wash … thoroughly after handling
*[P270]: Do not eat, drink or smoke when using this product
*[P271]: Use only outdoors or in a well-ventilated area
*[P280]: Wear protective gloves/protective clothing/eye protection/face protection
*[P301+312]: IF SWALLOWED: Call a POISON CENTER or doctor/physician if you feel unwell
*[P302+352]: IF ON SKIN: Wash with soap and water
*[P304+312]: IF INHALED: Call a POISON CENTER or doctor/physician if you feel unwell
*[P304+340]: IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing
*[P305+351+338]: IF IN EYES: Rinse continuously with water for several minutes. Remove contact lenses if present and easy to do – continue rinsing
*[P312]: Call a POISON CENTER or doctor/physician if you feel unwell
*[P321]: Specific treatment (see … on this label)
*[P322]: Specific measures (see … on this label)
*[P330]: Rinse mouth
*[P332+313]: If skin irritation occurs: Get medical advice/attention
*[P337+313]: Get medical advice/attention
*[P362]: Take off contaminated clothing and wash before reuse
*[P363]: Wash contaminated clothing before reuse
*[P403+233]: Store in a well ventilated place. Keep container tightly closed
*[P405]: Store locked up
*[P501]: Dispose of contents/container to …