Stepwise dilution of a sample by a constant factor to obtain countable concentrations.
Each step dilutes by a factor (such as 1 in 10); counting colonies on plates gives colony-forming units: CFU/mL = colonies / (dilution × volume plated). Plates with 30 to 300 colonies are counted.
Each tenfold dilution reduces counts tenfold. Plate several replicates. Calculate original concentration by multiplying back.
Key idea: dilution gives countable colonies.
Stepwise dilution of a sample by a constant factor to obtain countable concentrations.
Serial Dilution is one of the 51 topics in Lab Methods & Biostatistics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Spectrophotometry, Standard Deviation, Mean, Median and Mode.
Counting bacteria in milk.
Work through the Beginner topics in Lab Methods & Biostatistics first, such as Scientific Method, Hypothesis, Variables, then return to Serial Dilution. Intermediate topics assume the Beginner vocabulary.
The closest topics to Serial Dilution are Spectrophotometry, Standard Deviation, Mean, Median and Mode, ELISA. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Serial Dilution. To practise the whole of Lab Methods & Biostatistics, use the Lab Methods & Biostatistics quiz.
Serial Dilution: Stepwise dilution of a sample by a constant factor to obtain countable concentrations. Spectrophotometry: Determines how much light of a given wavelength a sample absorbs, linked to concentration by the Beer-Lambert law. Read both side by side and note what each one explains.
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Spectrophotometry and explain the difference aloud. Finally, take the Lab Methods & Biostatistics quiz and come back to this page for any question you miss.
Determines how much light of a given wavelength a sample absorbs, linked to concentration by the Beer-Lambert law.
📊 Lab Methods & BiostatisticsA measure of spread showing how far values typically lie from the mean.
📊 Lab Methods & BiostatisticsMeasures of central tendency summarising a data set.
📊 Lab Methods & BiostatisticsAn antibody-based assay that detects and quantifies proteins or antibodies in samples.
📊 Lab Methods & Biostatistics