Microbial challenge test on ethylhexylglycerin

Refer to the USP27 USP27 micro-anti-corrosion efficacy test. The compound samples were challenged in a body lotion and a deep hydrating serum.

Sample preparation: Weigh 100 g of the cosmetic base sample, add it to the sterilized container, add the mixed bacterial suspension, and mix well. The amount of bacteria per gram of sample was 5 × 10 6 CFU/g. Then placed at 28 °C. Sampling and analysis at 0 d, 7 d, 14 d, 21 d and 28 d of inoculation: accurately weigh 10 g of sample and add it to a conical flask containing glass beads and 90 mL of sterile saline, fully shaken and mixed. Evenly, this suspension was a 1:10 dilution; it was then diluted 1:10 with physiological saline. The bacteria contained in the sample were counted by the plate pour method and cultured at 37 ° C for 48 h.
Each strain is inoculated in a suitable medium and cultured at 37 ° C (bacteria) or 28 ° C (mold). After 2 days of bacterial culture, mold culture was carried out for 3 d to 5 d, and appropriate colonies were selected in sterile physiological saline to prepare mixed bacteria (1 × 10 ⁸ /mL) or mixed mold suspension ( 1 × 10 ⁷ /mL), stored at 4 °C for later use.
28 d microbial challenge test for one-time addition: Weigh 30 g of each test sample, add mixed bacteria or mixed mold suspension, and the final bacteria content per gram of test cream is 5 × 10 ⁶ bacteria and 3 × 10 ⁵ molds. Then mix well and place at 28 °C. Sampling and analysis at 0 d, 7 d, 14 d, 21 d and 28 d of inoculation: Accurately weigh 3 g of sample, add it to a sterile conical flask containing glass beads, and add 27 mL of sterile saline. Shake well and mix. This suspension is a 1:10 dilution; then dilute with 10 times the sterile saline. The amount of bacteria contained in the test sample was counted according to the flat pour method. The bacteria were cultured at 37 ° C for 48 h, and the mold was cultured at 28 ° C for 4 d.