Detection and Imaging of Chrome Yellow (Lead Chromate) in Latent Prints, Solid Residues, and Minerals by Laser-Desorption-Ionization Mass Spectrometry (LDI-MS).

Author(s) Zheng, Z.; Pavlov, J.; Attygalle, A.B.
Journal J Mass Spectrom
Date Published 2017 Mar 21
Abstract

In the past, Chrome Yellow (lead chromate, PbCrO4 ), a bright orange-red substance, has been widely used as an inorganic pigment in the production of paints, coatings, and plastics. Herein, we demonstrate that laser desorption/ionization mass spectrometry (LDI-MS) is a powerful tool for the detection of lead chromate in solid residues. In fact, lead chromate in trace amounts is easily detectable by LDI-MS even from residues left as latent prints. For example, a latent print obtained by stamping the exposed laterally cut surface of a pencil over 50 years old on an acetonitrile-moistened paper, was successfully imaged for both lead and chromate using a Synapt G2 HDMS mass spectrometer. After rastering the print with a 355 nm laser beam and recording positive- and negative-ion mass spectra over the range m/z 50-1200, we generated false-color "heat maps" (single-ion images) for (208) Pb(+•) (m/z 207.98) and for Cr2 O6(-•) (m/z 199.85). The heat maps matched closely with the faint visual image of the pencil imprint. Moreover, our results confirmed that lead chromate was used in the pigment coating of old pencils. Evidently, LDI-MS imaging is an efficient procedure to survey for the presence of lead and chromate in minerals and other materials.

DOI 10.1002/jms.3931
ISSN 1096-9888
Citation Zheng Z, Pavlov J, Attygalle AB. Detection and Imaging of Chrome Yellow (Lead Chromate) in Latent Prints, Solid Residues, and Minerals by Laser-Desorption-Ionization Mass Spectrometry (LDI-MS). J Mass Spectrom. 2017.

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