Dehydrated culture media
TSA Letheen Agar
For the microbiological analysis of cosmetics.
- Cat. No.
- LC-1396
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
TSA Letheen Agar is a highly nutritious agar and it is recommended for use in the microbiological testing of cosmetics. It can be used to inactivate quaternary ammonium compounds and other preservatives when establishing the number of bacteria present in cosmetics and other materials.
Key features
Applications
Detection (general use).
Industry
Cosmetics.
Preparation
45.7 g in one liter of distilled water; boil for one minute, sterilize in autoclave at 121 °C for 15 minutes.
Principles and uses
Pancreatic digest of casein and papainic digest of soy bean provide nitrogen, vitamins, minerals and amino acids essential for growth. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Lecithin and Tween 80 neutralize quaternary ammonium compounds and partially neutralize the preservative system commonly found in cosmetics. Bacteriological agar is the solidifying agent.
The medium is also used for microbiological samples from surfaces that have been treated with disinfectants.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige |
| Color of the prepared medium | Amber, slightly opalescent |
| Final pH (25 °C) | 7.2 ± 0.2 |
| Amount per litre | 45.7 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Bacteriological agar | 15 |
| Lecithin | 0.7 |
| Pancreatic digest of casein | 15 |
| Papainic digest of soy bean | 5 |
| Sodium chloride | 5 |
| Tween 80 | 5 |
Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.
Preparation and use
Preparation
Suspend 45.7 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Dispense into appropriate containers and sterilize in autoclave at 121 °C for 15 minutes.
Instructions for use
- Inoculate on the surface.
- Incubate the tubes at 35 ± 2 °C for 18-24 hours.
- Reading and interpretation of the results.
Quality control
Microbiological test
Incubation conditions: 35 ± 2 °C / 18-24 h.
| Microorganism | Specification |
|---|---|
| Staphylococcus epidermidisATCC 12228 | Good growth |
| Salmonella typhimuriumATCC 14028 | Good growth |
| Escherichia coliATCC 25922 | Good growth |
| Staphylococcus aureusATCC 25923 | Good growth |
| Pseudomonas aeruginosaATCC 27853 | Good growth |
Bibliography
- FDA Bacteriological Analytical Manual (BAM) 1995. Microbiological Methods for cosmetics, Letheen Agar (modified). Letheen Broth (modified).
What you receive
The product
Shipped under controlled temperature when the product requires it.
Lot certificate
Every lot comes with its certificate.
Tracked shipment
Follow your shipment live, from our warehouse to your lab.
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