Serial Dilution Concentration

What is this formula?

The serial dilution concentration formula calculates the concentration obtained after performing multiple consecutive dilutions using the same dilution factor at each step.

When to use it

Use this formula in microbiology, analytical chemistry, pharmaceutical testing, environmental analysis, and laboratory protocols involving repeated dilutions.

Example

A solution with an initial concentration of 1000 mg/L is diluted three times using a dilution factor of 10 at each step.

Data:

C0 = 1000 mg/L

DF = 10

n = 3

Formula:

Cn = C0 / DF^n

Substitution:

Cn = 1000 / 10^3

Cn = 1000 / 1000

Result:

Cn = 1 mg/L

The final concentration after three serial dilutions is 1 mg/L.

Applications

- Microbiological plate counting

- Calibration standards

- Environmental testing

- Pharmaceutical quality control

- Analytical chemistry laboratories

Note

This formula assumes that every dilution step uses the same dilution factor. If different dilution factors are used at different stages, the overall dilution must be calculated by multiplying the individual dilution factors.