US scientists have developed a non-destructive method to detect possible forged documents. 

The technique, developed by Graham Cooks at Purdue University, Indiana, and his colleagues, combines 2D molecular imaging with ambient mass spectrometry (MS). 

Current methods for document analysis regularly use a chromatographic step before MS analysis. This means that parts of the document need to be cut up, and requires time-consuming solvent extraction steps. 

Cooks' method uses DESI (desorption electrospray ionization mass spectrometry) under ambient conditions, where the analyte is electrosprayed with a solvent to generate charged droplets for MS analysis. This method not only reduces the number of sample treatment steps, but also damages a smaller amount of the surface. The team was able to use the technique to identify if and where handwritten text had been altered. 

'The use of DESI and imaging DESI for the forensic analysis of inks represents an exciting new application of the technique,' said Colin Creaser, professor of analytical chemistry at Nottingham Trent University, UK. In addition, the imaging aspect of the technique means that the analysis can be highly targeted, generating position-specific mass spectra. Cooks and his team believe that this technique has huge potential. 

Cook's colleague Demian Ifa explained, 'The ability that DESI provides of examining materials in the ambient environment encourages new applications. It has the potential to become an industry standard, not only for this particular problem but for many related analytical measurements.' 

Michele Zgraggen