Separating the guilty and the innocent: Chemistry World feature

Leon Barron (L) and Denise Syndercombe-Court (R), Division of Analytical & Environmental Sciences have been interviewed by Chemistry World for a feature piece about the importance of Chromatography in forensic science.

Chromatography is a technique for separating components of a mixture on the basis of the relative amounts of each component, distributed between a moving fluid stream (the mobile phase) and a contiguous (stationary phase). The mobile phase may be either a liquid or a gas, while the stationary phase is either a solid or a liquid.

Dating back to the early 1900’s, chromatography went largely unnoticed until after the Second World War and is now recognised as one of the most versatile and widely used analytical techniques. The process of allowing scientists to separate and analyse complex mixtures of substances makes it uniquely suited to the area of forensic science.

‘Criminal investigations often involve analysis of complex mixtures, perhaps involving soil, water, debris, body fluids or even bone. Forensic scientists have been using this technique for half a century, and it has now become the “gold standard” technique in forensic chemistry.’ Explains Leon. 

Over the last 50 years, chromatography has played a large part in solving some of the most infamous criminal cases, including the London bombings on 7 July 2005 and the Harold Shipman case. Today, several different forms of chromatography are routinely used, often in combination with mass spectrometry, to screen for and identify existing and new types of explosives. This analysis has become so sensitive, that is now also used to detect traces of illicit drugs. Facilities that use this process include the World Anti-Doping Agency accredited Drug Control Centre at King’s College London, which undertook all the drug testing for the London 2012 Olympics.

DNA profiling has become so sophisticated, that it is now possible to identify individuals using smaller and smaller samples of DNA. Whilst this has benefits, such as helping to convict criminals, it can also have disadvantages, such as implicating the innocent. Speaking about a case in the UK, where DNA appeared to implicate a man of rape in Manchester despite his insistence he had never been there, Denise Syndercombe-Court said ‘This suspect was arrested for spitting at a policeman, but the rape victims samples were contaminated in the lab with a small amount of his DNA. Has this not been discovered, a petty criminal would have been convicted of a much more serious offence.’

You can read the full article, by Clare Sansom on the Chemistry World website.