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A possible new oxidation marker for hair adulteration: Detection of PTeCA (1H‐pyrrole‐2,3,4,5‐tetracarboxylic acid) in bleached hair
Author(s) -
Eisenbeiss Lisa,
Binz Tina M.,
Baumgartner Markus R.,
Steuer Andrea E.,
Kraemer Thomas
Publication year - 2020
Publication title -
drug testing and analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.065
H-Index - 54
eISSN - 1942-7611
pISSN - 1942-7603
DOI - 10.1002/dta.2713
Subject(s) - chemistry , hydrogen peroxide , pyrrole , chromatography , degradation (telecommunications) , biochemistry , organic chemistry , telecommunications , computer science
Hair analysis has become a valuable tool in forensic toxicology to assess drug or alcohol abstinence. Yet, hair adulteration by cosmetic products presents a major challenge for forensic hair analysis. Oxidative treatments, e.g. bleaching, may lead to analyte loss and thereby to false negative results. Currently, the eumelanin degradation product 1H‐pyrrole‐2,3,5‐tricarboxylic acid (PTCA) serves as a marker for oxidative hair treatment, but requires the definition of cut‐off values. To investigate further eumelanin degradation products as markers for oxidative hair treatment, hair samples with and without in vitro bleaching (hydrogen peroxide (H 2 O 2 ) concentrations 1.9% up to 12%; incubation times 15 min, 30 min, 60 min) were analyzed by liquid chromatography coupled to high‐resolution time of flight mass spectrometry (HPLC‐HRMS). The distribution of eumelanin degradation products along the hair shaft was investigated for routine applicability after segmentation of cosmetically untreated hair samples and authentically treated hair samples. The signals of the eumelanin degradation products PTCA, 1H‐pyrrole‐2,3,4‐tricarboxylic acid (isoPTCA), and 1H‐pyrrole‐2,3,4,5‐tetracarboxylic acid (PTeCA) were found to be significantly elevated after in vitro bleaching already with low H 2 O 2 concentrations and after short incubation times. In contrast to PTCA and isoPTCA, PTeCA was not detectable in cosmetically untreated segments up to 12 cm from hair root and was only formed through the oxidation process. The results of the study show that the detection of PTeCA within the proximal 3 to 6 cm segment can be applied to reliably detect hair adulteration attempts through hair bleaching.