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SOP for Neutralization of Inhibitory Substances

OBJECTIVE
To lay down a procedure for neutralization of inhibitory substances.

SCOPE
This SOP is applicable to neutralization of inhibitory substances present in the test preparation for microbiological analysis at XYZ Limited.

RESPONSIBILITY
Microbiologist – Responsible for doing activity.
QC Head – Responsible for implementing the procedure.
QA Head – Overall Compliance.

PROCEDURE
  • Before doing regular microbial analysis, validation is to be conducted to demonstrate the absence of inhibitory substance which may affect the growth of the microorganisms present in the article under test condition.
  • This can be done by adding 1 mL of not less than 10-3 dilution of a 24 hours broth culture of following microorganisms to the first dilution (in pH 7.2 phosphate buffer, fluid soya bean casein digest medium or fluid lactose medium) of the test material and follow the common test procedure as per current version of General Test Procedure GP/043.
  • Test cultures:
  1. Escherichia coli
  2. Staphylococcus aureus
  3. Pseudomonas aeruginosa
  4. Salmonella
  • If the organism fail to grow, the test preparation modified by the following options
  1. By increasing the volume of diluent, the quantity of test material remains the same.
  2. By adding suitable inactivating agents (4.0 % Polysorbate 20 or 0.05 % Polysorbate 80 & 0.5% Soya lecithin).
  3. By combining the both.
  • If it is not possible to recover the inoculated viable culture, alternatively go for membrane filtration method.
  • In the case of article which is not suitable for applying the membrane filtration, continue the plate count method to establish the spectrum of inhibition and bactericidal activity of the article.
  • This may indicate that the article is not likely to be contaminated with the given species of micro-organisms due to the bactericidal activity of the product.

ABBREVIATIONS:
QC: Quality Control
QA: Quality Assurance
SOP: Standard Operating Procedure
%: Percentage

ANNEXURES
Nil

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