251275 Sigma-Aldrich

Citric acid

ACS reagent, ≥99.5%

  • CAS Number 77-92-9

  • Linear Formula HOC(COOH)(CH2COOH)2

  • Molecular Weight 192.12

  •  Beilstein/REAXYS Number 782061

  •  EC Number 201-069-1

  •  MDL number MFCD00011669

  •  eCl@ss 39021801

  •  PubChem Substance ID 24855122



Related Categories ACS Grade Buffers, Acids, Acids & Bases, Analytical/Chromatography, Biochemicals and Reagents,
Quality Level   200
grade   ACS reagent
assay   ≥99.5%
expl. lim.   8 %, 65 °F
impurities   Substances carbonizable by hot sulfuric acid, passes test
ign. residue   ≤0.02%
pKa    (1) 3.13, (2) 4.76, (3) 6.4
mp   153-159 °C (lit.)
anion traces   chloride (Cl-): ≤0.001%
  oxalate (C2O42-): passes test (limit about 0.003%)
  phosphate (PO43-): ≤0.001%
  sulfate (SO42-): ≤0.002%
cation traces   Fe: ≤3 ppm
  Pb: ≤2 ppm
SMILES string   OC(=O)CC(O)(CC(O)=O)C(O)=O
InChI   1S/C6H8O7/c7-3(8)1-6(13,5(11)12)2-4(9)10/h13H,1-2H2,(H,7,8)(H,9,10)(H,11,12)
Gene Information   human ... SRC(6714)


General description

Citric acid is an organic acid commonly used as a chelating agent, a buffering agent, for pH adjustment and derivatization.


Citric acid has been used to prepare:
• Phosphate citrate buffer for use in enzyme-linked immunosorbent assay.
• Citrate-stabilized ceria aqueous sol, which was employed in the synthesis of cerium oxide nanoparticles.
• Citric acid-Na2HPO4-buffered stock solution for use in the determination of fecal urease activity.
• Anticoagulant citrate dextrose solution A (ACD-A), which is employed during the isolation of blood-derived endothelial progenitor cells.

Citric acid has also been used:
• In a novel process which allows controlling of the particle size during the synthesis of palladium cuboctahedrons.
• To prepare citric acid-derived carbon nanodots (CNDs) by bottom-up carbonization method.
• As a bi-component chelating agent for the synthesis of Li4Ti5O12 (lithium titanate oxide) by a novel sol–gel method.


1, 2.5 kg in poly bottle

12 kg in fiber drum

5, 100, 500 g in poly bottle

Other Notes

Go to Redi-Dri Product Listing 791725

Legal Information

Redi-Dri is a trademark of Sigma-Aldrich Co. LLC

Safety & Documentation

Safety Information

GHS07  GHS07
Signal word 
Hazard statements 
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


MSMLS Online Plate Map

Metabolite descriptors included with the software download upon purchase of the product include: Name, Parent CID, molecular formula, molecular weight, CAS, ChEBI, HMDB ID, PubChem Compound and Subst...
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OAMLS Online Plate Map

OAMLS compounds are conveniently provided at 5µg per well, enough for multiple injections. These are high purity (>95%) compounds supplied in an economical, ready to use format. Compounds are arrange...
Keywords: Metabolites

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