title: Depth profiling of inks in authentic and counterfeit banknotes by electrospray laser desorption ionization/mass spectrometry.
abstract: Electrospray laser desorption ionization is an ambient ionization technique that generates neutrals via laser desorption and ionizes those neutrals in an electrospray plume and was utilized to characterize inks in different layers of copy paper and banknotes of various currencies. Depth profiling of inks was performed on overlapping color bands on copy paper by repeatedly scanning the line with a pulsed laser beam operated at a fixed energy. The molecules in the ink on a banknote were desorbed by irradiating the banknote surface with a laser beam operated at different energies, with results indicating that different ions were detected at different depths. The analysis of authentic $US100, $100 RMB and $1000 NTD banknotes indicated that ions detected in 'color-shifting' and 'typography' regions were significantly different. Additionally, the abundances of some ions dramatically changed with the depth of the aforementioned regions. This approach was used to distinguish authentic $1000 NTD banknotes from counterfeits. Copyright © 2015 John Wiley & Sons, Ltd.
authors.affiliation: Investigation Bureau, Ministry of Justice, New Taipei, Taiwan.
authors.forename: Yi-Ying
authors.initials: YY
authors.lastname: Kao
authors.affiliation: Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan.
authors.forename: Sy-Chyi
authors.initials: SC
authors.lastname: Cheng
authors.affiliation: Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan.
authors.forename: Chu-Nian
authors.initials: CN
authors.lastname: Cheng
authors.affiliation: Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan.|Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Jentaie
authors.initials: J
authors.lastname: Shiea
mesh_terms: D007281:Ink; D010209:Paper; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods
keywords: ambient mass spectrometry; banknote; depth profiling; electrospray laser desorption ionization; money counterfeiting