Application of micro-attenuated total reflectance FTIR spectroscopy in the forensic study of questioned documents involving red seal inks.

Red seal inks from Korea (6), Japan (1) and China (6) were studied to investigate the feasibility of micro-attenuated total reflectance (ATR) FTIR spectroscopy as a tool in the forensic study of questioned documents involving seal inks. The technique was able to differentiate red seal inks of similar colors and different manufacturers. Blind testing has shown that micro-ATR FTIR can identify the origin of the red seal inks with accuracy. Data gathered were converted to a database for future reference. Also, the technique was also successful in determining the sequence of heterogeneous line intersection from a personal seal and a ballpoint pen. The results show that micro-ATR FTIR can be a valuable non-destructive tool for the objective analysis of questioned documents involving different red seal inks.