Raman spectroscopy helps fight crime with no delay

Representatives from Renishaw (Gloucestershire, England) will describe practical forensic results from the company's StreamLine Plus Raman spectroscopy microscope at the upcoming 5th European Academy of Forensic Science conference (September 8, 2009; Glasgow, Scotland), where the company will be exhibiting.

Knowing when the line is crossed
The StreamLine Plus has been used to tackle difficult and time-consuming everyday issues faced by the forensic community. One such issue is the nondestructive composition analysis of suspected illegal narcotic tablets. Another is the analysis of ink lines that cross on documents to see which ink line was put down first (such ink lines can, for example, be deposited by a ball-point pen or an inkjet printer); such information can often be used to determine whether a document is genuine or forged.

The small sampling volume and high chemical sensitivity afforded by Renishaw's Raman method allows such measurements to be taken at unparalleled speeds, says the company.

Fast data collection
Because StreamLine Plus is an imaging technique, data collection and analysis occurs 200 times faster than for point-by-point mapping approaches; 4000 spectra are collected in less than a minute. Resolution can range from millimeters to submicrometer; wavelengths from the UV to the near-IR can be used.

Blind trials indicate that the StreamLine Plus is three times more successful than traditional techniques in determining the deposition order of crossing ink lines. Unambiguous chemical characterization is coupled with minimal sample preparation, contact-free laser interaction, and speedy analysis, according to Renishaw. The resulting easy-to-understand images are said by Renishaw to enable results to be presented and interpreted by nonexperts--vital in court-case scenarios

Other forensic challenges, where identification of microcontaminants over large areas is
crucial, can be overcome, such as:

--explosives detection on fabrics

--analysis of narcotic microparticles in fingerprints

--investigating the chemical composition of unknown tablets

Michael Ansell, an independent forensic-document analyzer with more than 30 years of experience, says that StreamLine Plus "is proving very useful in current case work."