ASTM E1054 Neutralization Evaluation Test
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The method is designed to test neutralizing agents for the purpose of inactivating, or quenching, active antimicrobial agents to ensure no inhibitory effects on microorganisms targeted for recovery. The method offers a wide array of neutralization options for test substances. Detailed within the method are the guidelines for neutralization assays with recoveries based in semi-solid medium, liquid medium, and membrane filtration.
Summary of the Neutralization Evaluation Test
The ASTM Neutralizer effectiveness test procedure consists of three separate evaluations, summarized below.
Neutralizer Effectiveness
- Suspension of test microorganism is prepared such that the suspension contains a low number of test microorganisms. A low number is used so that the microorganisms themselves do not help quench the active ingredient.
- An aliquot of the active ingredient suspension is added to the neutralizer under study, followed by addition of test substance containing active antimicrobial agent.
- Neutralizer effectiveness is assessed by qualitative and quantitative techniques measuring test microorganism growth.
Neutralization Toxicity
- A suspension containing a low number of test microorganism is prepared.
- An aliquot of the active ingredient suspension is added to the neutralizer under study, followed by addition of Phosphate Buffered Saline.
- Neutralizer toxicity is assessed by qualitative and quantitative techniques measuring test microorganism growth.
Test Organism Viability
- A suspension containing a low number of test microorganism is prepared.
- An aliquot of this suspension is added to Phosphate Buffered Saline.
- Test organism viability is assessed by qualitative and quantitative techniques measuring test microorganism growth.
Strengths of the Neutralization Evaluation Test
- The method accounts for a variety of active antimicrobial agents within various substrates and proposes effective neutralization options
- The method accounts for effectiveness, toxicity, test organism viability and test material control within the appropriate neutralizer.
- Sets the precedent for complete active antimicrobial agent inactivation
- The method is conducted in triple replicate to account for variability within antimicrobial test substance
Weaknesses of the Neutralization Evaluation Test
- Study uses cells that have not been exposed to any antimicrobial agents, which does not factor in any sub-lethal damage experienced which may affect viability/recovery.
Microchem Laboratory puts a great deal of time and thought into running excellent, scientifically defensible antimicrobial tests. Neutralization verification is an important component of that effort. The ASTM E1054 method is one of the most rigorous ways to verify neutralizer effectiveness; there are others that are equally defensible. Whether we use this method or another, we always make sure that neutralization is effective when testing disinfectants.
