DNA Science

Extraction

The aim of the extraction process is to obtain a solution of single stranded DNA from the case sample. It is preferred that the DNA solution be as clean and free from impurities as is possible. Such impurities can arise from the cellular material itself or from contaminants present with the sample submission; these could inhibit reactions later in the process.

Extraction is one area of DNA profiling that is highly susceptible to contamination. All samples must be handled with utmost care during this process, ensuring that no two sample tubes are open at the same time. To validate each extraction batch, a blank empty tube is used that should contain no DNA. This is termed the 'extraction negative'. The extraction negative is profiled alongside the batch of samples. A 'no profile' result provides evidence of a successful extraction, free from contamination.