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The Detection of Multiply Charged Dyes Using Matrix‐Assisted Laser Desorption/Ionization Mass Spectrometry for the Forensic Examination of Pen Ink Dyes Directly from Paper
Author(s) -
Dunn Jamie D.,
Allison John
Publication year - 2007
Publication title -
journal of forensic sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.715
H-Index - 96
eISSN - 1556-4029
pISSN - 0022-1198
DOI - 10.1111/j.1556-4029.2007.00535.x
Subject(s) - mass spectrometry , desorption , chemistry , ionization , benzoic acid , matrix assisted laser desorption/ionization , analytical chemistry (journal) , matrix (chemical analysis) , ion , chromatography , organic chemistry , adsorption
Abstract: Laser desorption mass spectrometry (LDMS) is emerging as a technique for questioned document examination. Its use is limited to detecting ink dyes that are neutral or singly charged. Several inks contain dyes that are multiply charged and LDMS cannot be employed for their identification. We have successfully detected >20 polyionic dyes that can be used in the manufacture of inks using matrix‐assisted laser desorption/ionization (MALDI) MS, directly from paper, with the matrix, 2‐(4‐hydroxyphenylazo)benzoic acid (HABA), and the additive, diammonium hydrogen citrate (DAHC). For example, Acid Violet 49, a charged dye containing one positively‐charged site and two negatively charged sulfonate groups, cannot be detected by LDMS, but forms intact, singly charged ions in the MALDI MS experiment. The method described is also useful for identifying multiply charged dye mixtures that are used in modern pen inks.