Direct sample analysis-mass spectrometry vs separation mass spectrometry techniques for the analysis of writing inks

Abstract Direct sample analysis (DSA) coupled with high resolution, high mass accuracy time of flight mass spectrometry (TOF-MS) is an emerging technique for the in situ analysis of various substances. DSA is similar to desorption electrospray ionization (DESI) and direct analysis in real time (DART), however, it uses an atmospheric pressure chemical ionization source for ionization of organic compounds. In this study, DSA was applied to the identification of 80 black and blue writing inks from both ballpoint and non-ballpoint pens. Approximately 3 mm sections of each writing was placed on the DSA sample holder and analyzed in an automated fashion. The holder can analyze 13 samples in a serial manner. Utilizing a high mass accuracy TOF-MS and using internal calibration, mass accuracy of