Discrimination of stamp pad inks using spectroscopic methods / Zuriati Ramli

Ink analysis is an important forensic procedure that can reveal useful information about questioned documents by comparison of the inks used to produce the questioned documents. In such cases, it is necessary to apply chemical methods that normally do not cause partial destruction of the examination materials. The aim of this work is to evaluate the possibility of discrimination between stamp pad inks by the use of spectroscopic methods; FTIR spectroscopy, UV-Vis spectroscopy and VSC 5000. Nine samples of different brands and colors of stamp pad inks were examined. Artline and Unicorn red inks and Colop and Artline blue inks cannot be differentiated based on the absorption of visible radiation. It could be due to the two brands use similar chemical compounds and they probably are of similar chemical compounds or compositions. However, all brands of black inks can be differentiated. It could be due to the inks may not have similar compositions. The IR spectra of all inks are similar although they are from different colors and brands probably due to the inks are comprised of chemical compounds having similar functional groups. The three brands of all the three colors, however, can be differentiated based on colorimetry measured on VSC 5000.