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Standard Interpretation

Standard: 2003 NELAC
Section: Appendix D.3.1.a.5
Link to relevant standard


How are other AB's interpreting this standard: 5) A sterility blank shall be performed on each batch of dilution water prepared in the laboratory and on each batch of pre-prepared, ready-to-use dilution water with non-selective growth media."

Are you requiring a sterility check with non-selective growth media for any dilution water (i.e. Deionized, distilled, etc.) or just those dilution waters whose preparation is described in microbiological procedures, like phosphate buffer water or peptone water?


If sterility is required for use (whether in-house or purchased), then sterility must be checked prior to use. If the water is being used to prepare media or buffered water, then a sterility check is not needed until after the reagent has been prepared. A sterility check must be performed on any dilution water.