Serial Dilution

The process of reducing the concentration^* of a solution by mixing small volume^*s of the original solution with water (or other solvent^*) over a number of uniform steps. The uniform nature of the process makes it possible to back-calculate characteristics of the original solution based on procedures performed the diluted samples. 

Often 10% or less of the original sample is used in the first step of a dilution series. As a result, the diluted sub-samples can be used for a variety of procedures without consuming the bulk of the original sample.  

A 10x dilution is obtained by mixing 1 part of a sample with 9 parts of a diluent so that the new solution is 10 times (10x) less concentrated than the original solution. The 10x dilution can then be diluted by a factor of 10 again by mixing it with 9 more parts of the diluent. This second step produces a 100x dilution. 

Serial dilutions are made when a sample is too concentrated for a particular procedure such as a colorimetric assay. The serial dilution process is also used to make the standard curves needed for many quantitative procedures.