Letheen Agar Base Modified (without Tween) is used with Tween 80 (Polysorbate 80) for the isolation of microorganisms from cosmetics in a laboratory setting. Letheen Agar Base Modified is not intended for use in the diagnosis of disease or other conditions in humans.

In 1948, Weber and Black described the value of a highly nutritional solid medium containing neutralising agents for quaternary ammonium compounds in sanitisers. The addition of Lecithin and Tween 80 (Polysorbate 80) to Tryptone Glucose Extract (TGE) Agar resulted in a medium that effectively neutralises quaternary ammonium compounds in testing of germicidal activity. Total neutralisation of disinfectants is critical. Disinfectant residues can result in a false negative (no-growth) test.

Letheen Agar Base Modified is based on the formula described in FDA Bacteriological Analytical Manual, and a modification of Letheen Agar Base. Letheen Agar Base Modified is recommended by the FDA for use in the microbiological testing of cosmetics.

• Analyte: non-selective
• Platform: dehydrated culture media
• Formula: letheen agar base 25.0g/L, enzymatic digest of casein 10.0g/L, enzymatic digest of animal tissue 10.0g/L, yeast extract 2.0g/L, sodium chloride 5.0g/L, sodium bisulfite 0.1g/L
• Grams per litre: 52.10
• Litres per 500g: 10.00
• Plates per 500g: 520.00