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 Registry 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,
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
Gene Information   human ... SRC(6714)



1, 2.5 kg in poly bottle

12 kg in fiber drum

5, 100, 500 g in poly bottle


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.

General description

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

Legal Information

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

Other Notes

Go to Redi-Dri Product Listing 791725

Safety & Documentation

Safety Information

GHS07  GHS07
Signal word 
Hazard statements 
Precautionary statements 
Personal Protective Equipment 
NONH for all modes of transport
WGK Germany 


Certificate of Analysis

Certificate of Origin

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MSMLS Online Plate Map

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