INHIBITION OF THE PRESERVATIVE SYSTEM OF TWO O/W EMULSIONS BY POLYSORBATE 80

Abstract

The inhibition of growth of microorganisms due to the bacteriostatic or ungistatic effect of the formulation may cause a false-negative result in microbiological analysis. Thus, the evaluation of the inhibitory capacity of the preservatives present in the sample is critical to an effective microbiological evaluation. The tests were performed to prove the absence of the inhibitory effect on the growth of microorganisms due to the inhibitory activity of these components. Inhibition of the formulation preservative effect was carried out by two methods: by the addition of 0.4 % polysorbate 80 and dilution. The sample was prepared using 10 g of each sample in 90 mL of 0.9 % saline, resulting in a 1:10 dilution. Also, it was added 0.4 % polysorbate 80 in saline solution to neutralize the parabens and imidazolidine in the formulations. The neutralization of the inhibitory effect was performed by using 0.4% polysorbate 80 and 1:10 dilution. It observed the growth of the following microorganisms: Staphylococcus aureus, Salmonella typhimurium, and Pseudomonas aeruginosa in all samples and the positive control, meaning the inactivation of the inhibitory effect of preservatives.