Fourier transform infrared spectroscopy and high performance thin layer chromatography for characterization and multivariate discrimination of blue ballpoint pen ink for forensic applications

Abstract

In the present work, fifty seven blue ballpoint pen ink samples were characterized by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy(ATR–FTIR) and discriminated on the basis of high performance thin layer chromatography (HPTLC) and ATR–FTIR spectroscopy coupled with multivariate analysis which otherwise seems to be alike and hence, undifferentiated. The approach of ATR–FTIR has proven out to be an effective tool for characterization of complex ink formulation and hence, ink’s systematic discrimination with the help of multivariate analysis. The overall discrimination for blue ballpoint pen ink with non–destructiveanalysis of ATR–FTIR come out to be 99.69%, which is highly significant in comparison to both visual inspection of the spectra (DP= 97.93%) and destructive HPTLC chromatography (DP=93.80%). The similar methodology can be applied in the real case work of forensic laboratories to check whether two entries of ink on a sheet of questioned document have a common origin or not.