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Ng, Lafontaine, and Brazeau published a study on ballpoint pen ink characterization by direct infusion to an electrospray ionization mass spectrometer (Ng et al. Seventy-seven inks were analyzed and used to create a searchable library.
Conneely, Mc Clean, Smyth, and Mc Mullan reported on Phthalocyanine and Azo dyes using electrospray ionization mass spectrometry and matrix-assisted laser desorption/ionization mass spectrometry (Conneely et al. In particular, the behavior of sulphonate groups in Copper Phthalocyanine pigments was of interest because of the presence of these pigments in blue ballpoint pen inks.
According to their results, the sulphonate groups are labile, producing some fragmentation in the electrospray ionization mass spectrometry experiment.
Huang, Yinon, and Sigman used liquid chromatography with ultraviolet-visible detection coupled to an electrospray ionization mass spectrometer to study extracted textile fiber dyes in forensic size samples (Huang et al. Six extracted dyes were characterized with comparison to reference standards. Figure 1 shows the chemical structures of some dyes and additives that were important in this study.
In addition, spectroscopic data is not obtained, although densitometry can be used to analyze spots for quantitative data when compared to a standard, assuming that the chemical identity is known (Aginsky 1994).
For example, the recent Martha Stewart conviction partially relied on ink-source-comparison evidence regarding a suspected stock worksheet alteration (Associated Press 2004).
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.
In this study, excess sample was analyzed by direct infusion into an electrospray ionization mass spectrometer.
Electrospray ionization is a soft ionization technique that results in multiply charged species and minimal fragmentation.