Τετάρτη, 3 Οκτωβρίου 2007
In the new issue of Journal of Forensic Sciences (Volume 52 Issue 5 Page 1212-1213, September 2007 ), Meenakshi Mahajan & S.P. Arya present a paper titled: "Examination of Writings Concealed by Black Pressure Sensitive Adhesive Tape".
Examination of concealed writing is often a challenge for forensic document examiners. Although the published literature describes many techniques, these are often only successful when the writing has been concealed by pencil, pen, or by spreading inks of different tint or by smearing of the writing with colored fluids. When black pressure sensitive adhesive (PSA) tape is used, these procedures are ineffective. The present report describes the use of a straight chain hydrocarbon to remove the PSA tape and allow a comparison of the concealed writing with that of a suspect. The use of the solvent had no observable effect on either the writing or the substrate. The procedure is rapid and easy to use and is also effective with other colored PSA tapes.
Journal of Forensic Sciences: http://www.blackwell-synergy.com/doi/abs/10.1111/j.1556-4029.2007.00537.x
The Detection of Multiply Charged Dyes Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry for the Forensic Examination of Pen Ink Dye
Στο καινούργιο e-τευχος του Journal of Forensic Sciences International (Volume 52 Issue 5 Page 1205-1211, September 2007 ), οι Jamie D. Dunn και John Allison παρουσιάζουν μια εργασία με τίτλο: "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".
In the new Issue of Journal of Forensic Sciences I (Volume 52 Issue 5 Page 1205-1211, September 2007 ), Jamie D. Dunn & John Allison present a paper titled: "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".
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.
Journal of Forensic Sciences: http://www.blackwell-synergy.com/doi/abs/10.1111/j.1556-4029.2007.00535.x
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