title: Hydrogen peroxide reactions on cocaine in hair using imaging mass spectrometry.
abstract: Today, forensic hair analysis is considered to be a standard method for identifying chronic drug users since information about drug use stored and located in hair can cover several months to even years. When interpreting these results, one should be aware of all kind of pitfalls. External factors such as bleaching might influence the analytical result. Although the effect of hydrogen peroxide on cocaine in a solution was described before, it was never investigated whether the described reaction products (ecgonine methylester, benzoylecgonine, hydroxynorcocaine and dihydroxycocaine) are indeed found on contaminated or user hair. Since it is of great importance in forensic hair analysis to know whether cocaine and/or reaction products are detectable in hair after bleaching, matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) was used to study the effect of hydrogen peroxide treatment on incorporated cocaine in hairs. Cocaine oxidation products were identified in a solution based on MS/MS spectra and spatial distribution of these products in hair was explored using MALDI TOF-MS. All images were accomplished by spraying α-Cyano-4-hydroxycinnamic acid (CHCA) as a MALDI-matrix. Images revealed a loss of detectability of cocaine and its reaction products in hairs already after a short bleaching period. Since all compounds of interest are found in the hydrogen peroxide and wash solution, these findings indicate that all evidence of cocaine use might be lost after a hair bleaching treatment. Therefore, forensic toxicologists should take into consideration whether hair samples were bleached before making any conclusions from hair analysis results.
authors.affiliation: FOM-Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands; KU Leuven Toxicology and Pharmacology, Herestraat 49, PO 922, 3000 Leuven, Belgium.
authors.forename: Eva
authors.initials: E
authors.lastname: Cuypers
authors.affiliation: FOM-Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.
authors.forename: Bryn
authors.initials: B
authors.lastname: Flinders
authors.affiliation: Netherlands Forensic Institute, Department of Pathology and Toxicology, Laan van Ypenburg 6, 2497 GB, PO Box 24044, 2490 AA The Hague, The Netherlands.
authors.forename: Ingrid J
authors.initials: IJ
authors.lastname: Bosman
authors.affiliation: Netherlands Forensic Institute, Department of Pathology and Toxicology, Laan van Ypenburg 6, 2497 GB, PO Box 24044, 2490 AA The Hague, The Netherlands.
authors.forename: Klaas J
authors.initials: KJ
authors.lastname: Lusthof
authors.affiliation: Netherlands Forensic Institute, Department of Pathology and Toxicology, Laan van Ypenburg 6, 2497 GB, PO Box 24044, 2490 AA The Hague, The Netherlands; van't Hoff Institute for Molecular Sciences, Faculty of Science, University of Amsterdam, PO Box 94157, 1090 GD Amsterdam, The Netherlands.
authors.forename: Arian C
authors.initials: AC
authors.lastname: Van Asten
authors.affiliation: KU Leuven Toxicology and Pharmacology, Herestraat 49, PO 922, 3000 Leuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Tytgat
authors.affiliation: FOM-Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands. Electronic address: r.heeren@amolf.nl.
authors.forename: Ron M A
authors.initials: RMA
authors.lastname: Heeren
mesh_terms: D003042:Cocaine / Q000032:analysis*; D019970:Cocaine-Related Disorders / Q000175:diagnosis; D053593:Forensic Toxicology; D006197:Hair / Q000737:chemistry*; D058206:Hair Bleaching Agents / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D009294:Narcotics / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D015813:Substance Abuse Detection
chemical_list: D058206:Hair Bleaching Agents; D009294:Narcotics; D006861:Hydrogen Peroxide; D003042:Cocaine
keywords: Cocaine; Forensic hair testing; Hydrogen peroxide; Imaging mass spectrometry