Forensic Analysis of Blue Ballpoint Pen Inks Using Capillary Electrophoresis<br>
Ink analysis involving the determination of specific chemicals can be a useful forensic tool in pen formula differentiation. Thin-layer chromatography is the most widely used forensic technique for ballpoint pen ink examinations; however, limited information is obtained. To address this issue, capillary electrophoresis using an ultraviolet-visible photodiode array detector was employed as an alternative analytical tool. Results were compared with thin-layer chromatography experiments to evaluate the sensitivity and usefulness of capillary electrophoresis. Dye components are rapidly separated, and identification is based on comparison of electrophoretic mobility values and ultraviolet-visible spectra with individually run dye standards. A database of ballpoint pen ink analyses and common-dye reference standards has been initiated for future forensic use. Capillary electrophoresis sample-preparation protocols were designed to closely mimic common procedures for handling ink evidence. Because of the small volume necessary for sample injection, the remaining solution could be further processed using current law enforcement procedures to obtain complementary data. Capillary electrophoresis method development, electropherograms, electrophoretic mobility values, ultraviolet-visible spectra, and electrospray ionization mass spectrometry data are reported.