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Dilution Factor Formula:
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The dilution factor (DF) is a dimensionless value used in microbiology to quantify the degree of dilution of a sample. It represents the factor by which the original sample has been diluted and is essential for calculating the original concentration of microorganisms in a sample.
The calculator uses the dilution factor formula:
Where:
Explanation: The dilution factor is calculated as the reciprocal of the fraction of the original sample that was plated. This simple relationship allows researchers to back-calculate the original concentration from colony counts.
Details: Accurate dilution factor calculation is crucial in microbiology for determining the original concentration of microorganisms in a sample, ensuring accurate colony counting, and maintaining the validity of experimental results in microbial studies.
Tips: Enter the fraction of sample plated as a decimal value (e.g., 0.1 for 1/10 dilution). The value must be greater than 0 and typically ranges between 0.0001 and 1.0 for most microbiological applications.
Q1: What is a typical range for dilution factors in microbiology?
A: Dilution factors typically range from 10 to 10^6 or higher, depending on the expected microbial concentration in the original sample.
Q2: How does dilution factor relate to concentration calculations?
A: The original concentration is calculated by multiplying the counted colonies by the dilution factor and dividing by the volume plated.
Q3: Why are serial dilutions used in microbiology?
A: Serial dilutions are used to achieve a countable number of colonies (30-300) on agar plates, which allows for accurate enumeration of microorganisms.
Q4: What is the difference between dilution factor and dilution ratio?
A: Dilution factor refers to the factor by which the sample is diluted (e.g., 10 for a 1:10 dilution), while dilution ratio expresses the proportion (e.g., 1:10).
Q5: How should I record dilution factors in lab notebooks?
A: Always record both the dilution factor and the method used to achieve it, including volumes transferred and diluent volumes, for reproducibility.