NCJ Number
130726
Date Published
1991
Length
24 pages
Annotation
This research evaluated HPLC (high performance liquid chromatographic) systems with diode array detection in their ability to differentiate closely related writing inks; HPLC was also tested in its differentiation of fiber dyes.
Abstract
The forensic examination of writing inks attempts to determine whether two or more entries were made with the same pen or same formula of ink and to ascertain the time frame in which an entry was made. The primary means of chemical analysis of inks is through thin layer chromatographic (TLC) separation of the nonvolatile dye components of the ink. This research anticipated that the improved resolution and sensitivity of HPLC compared with TLC would enable minor differences to be detected in the tested samples. Using a simple chromatogrphic system, together with a Spectra Physics multiwavelength detection system, over 100 nonball pen inks were distinguished. The majority of these had not previously been separated by traditional methods. The system was also found to be useful for the comparison of light-colored fiber dyes when TLC and microspectrophotometry had failed to produce useful data. The HPLC system was found to have advantages over less sophisticated means of dye comparison; sensitivity is greatly improved to allow the detection of picograms of sample, and the increased resolution results in far more information. 10 figures