ISPE Glossary of Pharmaceutical and Biotechnology Terminology

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Efficiency of cleaning, disinfection, or a process involving these actions singly or in combination, is expressed as the logarithm base 10 of the ratio of initial and final quantities and concentrations of tracer (see 3.7, DIS 14698-3) Symbol = E. ISO 14698-3.

NOTE: The efficiency, a non-dimensional number, is the number of reductions by order of magnitude; i.e. of divisions by 10 of the tracer quantity or concentration. Expressions such as log cycle number or log number are not recommended. Examples:

a) Where the initial concentration of microorganisms (by gram of biofilm, or by cm² of surface) is 107 and the final concentration is 10³, the efficiency is then: E = log10 (107/10³) = log10 (104) = 4.

b) Where the initial quantity of soiling is 300 mg per cm², and the final quantity is 20mg per cm², the efficiency is then: E = log10 (300/20) = log10 (15) = 1.2.

Publication Source: ISO/TC209 Working Groups at 2001-03-31 – Committee Draft ISO/CD 14644-6 “Cleanrooms and associated controlled environments” – Part 6: Terms and Definitions

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