Patent ID: 7679740

Claim:
A method of assessing the occurrence of an unknown substance in a sample comprising multiple entities, the method comprising: providing a reference library comprising a plurality of reference data sets representative of at least one known substance; assessing a first feature of the entities wherein the first feature is characteristic of the unknown substance; selecting a region of interest of the sample wherein said region of interest comprises at least one entity exhibiting said first feature; obtaining a Raman test spectrum from said region of interest; performing a first comparison of said Raman test spectrum with said reference data sets using Euclidian distance; if said first comparison, results in a match to one of said reference data sets representative of a known substance, identifying said unknown substance as the known substance; if said comparing does not result in a match to one of said reference data sets, perform a second comparison of said Raman test spectrum with said reference data sets using Mahalanobis distance; and if said second comparison results in a match to one of said reference data sets representative of a known substance, identifying said unknown substance as the known substance.