Observation on the preservative effect of preservatives

Observation on the preservative effect of preservatives

Liquid pharmaceuticals are easily contaminated by microorganisms, especially aqueous liquid pharmaceuticals containing nutritious substances such as sugars, proteins, etc., which are more likely to cause the growth and reproduction of microorganisms. Liquid preparations of antibiotics and some chemically synthesized disinfectants and antiseptics are sometimes also contaminated with bacteria and mildew. This is because various antibacterial drugs have no bacteriostatic effect on microorganisms outside their own antibacterial spectrum. Once the liquid medicine is infected with bacteria and mold, it will seriously affect the quality of the medicine and endanger human health, and can no longer be used for clinical applications. The 2000 edition of “Chinese Pharmacopoeia” clearly stipulates the limit requirements and inspection methods for the bacterial count of liquid pharmaceuticals. To make the liquid medicine meet the pharmaceutical hygiene standards, strong antiseptic measures must be taken. The following measures are generally taken: prevention of contamination, sterilization and addition of preservatives.
Simple syrup is a hypertonic solution, which is not conducive to the growth and reproduction of bacteria. It is a nutrient liquid after dilution, which is beneficial to the growth and reproduction of bacteria. Ethyl paraben is an excellent preservative, with an effective bacteriostatic concentration of 0.06% in the range of pH 5 to 7, and has a wide range of antibacterial effects on mold, yeast and bacteria. The antiseptic effect was observed through control experiments and bacterial culture. .

【Experiment content】
1. Formulation of preservative-containing and preservative-free simple syrup dilutions.
(1) Measure 50 ml of simple syrup, add purified water to dilute to 100 ml, stir well, divide into two parts A and B, 50 ml each, and measure the pH value.
(2) Add 1.0 ml of purified water to solution A, add 1.0 ml of ethyl paraben in alcohol solution (each ml contains 30 mg of ethyl paraben), and mix well.
2. Bacteria culture and observation.
3. Take 2 sterilized petri dishes, pour liquid B into petri dishes respectively, and expose to the air for half an hour; take another 2 sterilized petri dishes, pour liquid A into petri dishes respectively, and prepare in the same way as control. The results were observed after culturing at 25-28 °C for 7 days.

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