Application of Raman Spectroscopy in Examinat...

Application of Raman Spectroscopy in Examination of Ink Samples Obtained From Questioned Documents

Author Name : Tanisha Karmakar

ABSTRACT In the Asian sub-continent hand signatures and stamps are commonly used for authenticating personal and official documents thus, analysis of handwriting (Graphology) and stamp-inks are critical for forensic investigation. With the advent of modernization, the methods for perpetrating forgery and alteration of documents, crimes including their falsification, questioned signatures, letters, notes, and bank cheques are increasing at an alarming rate and becoming more sophisticated. Thus, in forensic investigations: (i) Characterization of inks, (ii) Differentiation of ink sequence in intersecting lines, and (iii) Dating of inks in questioned documents are essential for solving disputation. Only in the '90s were the analysis of ink through chromatographic and electrophoretic techniques invented. Analytical methods like- UV-visible spectrophotometer, Thin Layer Chromatography (TLC), High-Performance Liquid Chromatography (HPLC), Capillary Electrophoresis, Gas Chromatography, and Mass Spectrometry have played important roles and have shown great potential for ink analysis. However, these methods call for sample preparation and ink extraction, thus being destructive, and compromising the document's integrity. Raman Spectroscopy is an attractive technique used for ink analysis because it combines chemical selectivity with ease and fast analysis. It does not require sample preparation from evidence and hence, is non-destructive. It can quantify and identify several trace elements making spectroscopic methods more reliable and objective.