Distillates - March 2012

Amino acid residues give away bloodstain's age

Chemists in the US have developed a quick and simple way to find out how old bloodstains are using natural fluorescence measurements. Knowing when blood has been spilled can help forensic scientists pinpoint when a crime took place, but current techniques - such as optical measurements of haemoglobin degradation - can be unreliable.  

Now, Mikhail Berezin and colleagues at Washington University in St Louis, US, have developed a technique that relies on the fluorescence lifetime of the tryptophan in blood proteins.