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Dilution Factor Formula:
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The dilution factor (DF) in microbiology represents the factor by which a sample has been diluted. It is calculated as the reciprocal of the fraction of the original sample that is plated, helping to determine the original concentration of microorganisms in a sample.
The calculator uses the dilution factor formula:
Where:
Explanation: The dilution factor indicates how many times the original sample was diluted. A higher dilution factor means the sample was more diluted before plating.
Details: Accurate dilution factor calculation is crucial for determining the original concentration of microorganisms in samples, ensuring proper colony counting, and obtaining reliable microbiological results in research and clinical settings.
Tips: Enter the fraction plated as a decimal value (e.g., 0.1 for 1/10 dilution). The value must be greater than 0 and typically less than or equal to 1.
Q1: What does a dilution factor of 10 mean?
A: A dilution factor of 10 means the original sample was diluted 10 times, and only 1/10 of the original concentration is present in the plated sample.
Q2: How is fraction plated different from dilution factor?
A: Fraction plated represents the portion of the original sample used, while dilution factor is the reciprocal of this fraction, indicating the degree of dilution.
Q3: When should serial dilutions be used?
A: Serial dilutions are used when the expected microbial concentration is unknown or varies widely, allowing for accurate colony counting across different dilution levels.
Q4: What are common dilution factors used in microbiology?
A: Common dilution factors include 10, 100, 1000, and 10,000, depending on the expected microbial concentration in the original sample.
Q5: How does dilution factor affect colony counting?
A: Proper dilution ensures colonies are countable (typically 30-300 colonies per plate) and helps calculate the original concentration accurately by multiplying colony count by the dilution factor.