Letheen Broth Base, AOAC (Powder)

Letheen Broth Base is used with Polysorbate 80 for the testing of quaternary ammonium compounds for antimicrobial acitivity. Polysorbate 80 is not supplied.\nIn 1948, Weber and Black described the value of a highly nutitional solid medium containing neutralizing agents for quaternary ammonium compounds for sanitizers (1). The addition of Lecithin and Polysorbate 80 to Tryptone Gluse Extract (TGE) Agar resulted in a medium that effectively neutralizes quaternary ammonium compounds while testing germicidal activity. Letheen Agar is a modification of TGE Agar with the addition of Lecithin and Polysorbate 80.\n\nLetheen Base was developed as a subculture medium for the neutralization of quaternary ammonium compounds in disinfectant testing. Quisno, Gibby and Foter discovered that adding lecithin and Polysorbate 80 to FDA Broth results in a medium that neutralized high concentrations of quaternary ammonium salts (2). he resulting medium, termed Letheen (a combination of Lecithin and Tween) was easy to prepare and clear in appearance, aiding to visual inspection for growth. Letheen Broth Base is recommended by the Association of Official Analytical Chemists (AOAC) for use with disinfectants containing cationic surface materials.\n\nLetheen Broth Base is specified for use by the American Society for Testing Materials (ASTM) in Standard Test Method for Presernatives in Water-Containg Cosmetivcs (4). Total neutralization of disinfectants is critical. Disinfectant residues can results in false negative (no growth) tests.

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SPECIFICATIONS

Catalog Number

L1672-10

Size

500g

References

1. Weber, G. R., and L. A. Black. 1948. Relative efficiency of quaternary inhibitors. Soap and Sanit. Chem. 24:134-139.\n2. Quisno, R., I. W. Gibby, and M. J. Foter. 1946. A neutralizing medium for evaluating the germicidal potency of the quaternary\nammonium salts. Am. J. Pharm. 118:320-323.\n3. Association of Official Analytical Chemists. 1995. Official methods of analysis, 16th ed. Association of Official Analytical\nChemists, Washington, D.C.\n4. American Society for Testing Materials. 1991. Standard test method for preservatives in water-containing cosmetics, E 640-78.\nAnnual Book of ASTM Standards, Philadelphia, PA.\n5. Erlandson, A. L., Jr., and C. A. Lawrence. 1953. Inactivating medium for hexachlorophene (G-11) types of compounds and some\nsubstituted phenolic disinfectants. Science. 118:274-276.\n6. Brummer, B. 1976. Influence of possible disinfectant transfer on Staphylococcus aureus plate counts after contact sampling. Appl.\nEnviron. Microbiol. 32:80-84.\n7. Favero (chm.). 1967. Microbiological sampling surfaces-a state of the art report. Biological Contamination Control Committee, American Association for Contamination Control.