NCJ Number
222156
Journal
Journal of Forensic Sciences Volume: 53 Issue: 1 Dated: January 2008 Pages: 107-115
Date Published
January 2008
Length
9 pages
Annotation
This paper reports on the use of laser desorption mass spectrometry (LDMS) to achieve the direct identification of copper phthalocyanine (CuPc) and chlorinated CuPc in paints, in order to distinguish between blue automobile paints in the absence of a matrix.
Abstract
The LDMS data obtained from model blue paints were consistent with those obtained for the eight powder pigments tested. Further, the LDMS analyses of the 40 blue automobile paint samples show characteristic mass spectral peaks for organic pigments, such as CuPc, chlorinated CuPc, and Pigment Violet 19. LDMS analysis thus distinguished between blue organic pigments in paint films as long as the mass spectra are different; however, further elemental analysis is required in order to distinguish between blue automobile paints that have the same patterns in LDMS spectra. In spite of such limitations, LDMS analysis of the CuPc pigments is expected to be useful for the identification of blue paints in forensic analyses. This technique may also be useful for identifying the organic colored components in order to distinguish between similar blue paints. The LDMS technique offers several advantages for forensic analyses. It enables quick analysis of small paint chips, i.e., chips smaller than 0.3 square millimeters. After analysis of the samples, the integrity of the samples was maintained for additional analysis. Samples were analyzed using a laser desorption time-of-flight mass spectrometer (Kraytos/Shimadzu Kompact MALDI 2 and Shimadzu AXIMA-CFR with high resolution) outfitted with a pulsed-nitrogen laser (337 nm, 3 ns, and 3 Hz). 3 tables, 9 figures, and 25 references