LETHEEN AGAR, MODIFIED *

In the early 40s, Weber and Black recommended the use of lecithin and polysorbate to neutralize the antimicrobial action of the quaternary ammonium compounds. In 1965, the methodology was accepted by AOAC for the antimicrobial assays and extended their use to all the cationic detergents. In 1978, the FDA incorporated it as pre-enrichment medium for every microbial examination of cosmetics. Letheen Agar, Modified is used to partially inactivate the preservatives in cosmetics being analyzed for the microbial content. This medium was originally recommended by APHA for use in microbial testing of water.

for screening cosmetic products for microbial contamination