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  • A9518 - Ampicillin sodium salt


A9518 Sigma-Aldrich

Ampicillin sodium salt

Synonym: D-(−)-α-Aminobenzylpenicillin sodium salt

  • CAS Number 69-52-3

  • Empirical Formula (Hill Notation) C16H18N3NaO4S

  • Molecular Weight 371.39

  •  Beilstein Registry Number 4119211

  •  EC Number 200-708-1

  •  MDL number MFCD00064313

  •  PubChem Substance ID 24891463


Related Categories A - K, Antibacterial, Antibiotics, Antibiotics A to Z, Antibiotics A-F,
color   white with slight yellow cast
mp   215 °C (dec.)(lit.)
solubility   H2O: soluble50 mg/mL
Featured Industry   Agriculture
antibiotic activity spectrum   Gram-negative bacteria
  Gram-positive bacteria
storage temp.   2-8°C


Frequently Asked Questions

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Used to select for ampicillin resistance in mutated and transformed cells.

Biochem/physiol Actions

Mode of Action: This is a ß-lactam antibiotic that inhibits bacterial cell-wall synthesis by inactivating transpeptidases on the inner surface of the bacterial cell membrane.

Mode of Resistance: Administration with ß-lactamase cleaves the ß-lactam ring of Ampicillin and inactivates it.

Antimicrobial Spectrum: Includes both gram-positive (similar to benzylpenicillin) and gram-negative bacteria (similar to tetracyclines and chloramphenicol.


This product has been reported stable as supplied at 25°C at 43% and 81% relative humidity for six weeks. Additional studies have shown that the stability of Ampicillin in solution is a function of pH, temperature and the identity of the buffer. It′s activity is quickly lost when stored above pH 7. Optimal storage conditions are suggested as 2-8°C, and pH 3.8-5 where its activity was retained at 90%+ for a week.


5, 25, 100 g in poly bottle

Preparation Note

Ampicillin is reported as slightly soluble in water, practically insoluble in alcohol, chloroform, ether and fixed oils but soluble in dilute acids or bases. The solution should not be autoclaved; a stock solution should be sterilized through filtration and stored frozen, where it will be stable for months.

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