Mapping the Chemistry of Hair Strands by Mass Spectrometry Imaging—A Review

Abstract

Hair can record chemical information reflecting our living conditions, and, therefore, strands of hair have become a potent analytical target within the biological and forensic sciences. While early efforts focused on analyzing complete hair strands in bulk, high spatial resolution mass spectrometry imaging (MSI) has recently come to the forefront of chemical hair-strand analysis. MSI techniques offer a localized analysis, requiring fewer de-contamination procedures per default and making it possible to map the distribution of analytes on and within individual hair strands. Applying the techniques to hair samples has proven particularly useful in investigations quantifying the exposure to, and uptake of, toxins or drugs. Overall, MSI, combined with optimized sample preparation protocols, has improved precision and accuracy for identifying several elemental and molecular species in single strands of hair. Here, we review different sample preparation protocols and use cases with a view to make the methodology more accessible to researchers outside of the field of forensic science. We conclude that—although some challenges remain, including contamination issues and matrix effects—MSI offers unique opportunities for obtaining highly resolved spatial information of several compounds simultaneously across hair surfaces.

A protein analysis-based method for authentication of human hair wigs

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Desenvolvimento de métodos de análise de cabelo por MALDI-TOF-MS e MALDI-MSI e avaliação de tratamentos cosméticos

“…A cutícula é a camada mais externa e é vital para proteger a estrutura interna de danos causados por fatores ambientais ou tratamentos cosméticos, sendo a camada mais afetada pelos componentes dos produtos capilares. Ela é formada por múltiplas camadas, cada uma com cerca de 0,5 µm de espessura (PHILIPSEN et al, 2021). Cada célula da superfície contém uma fina membrana proteica, a epicutícula, coberta por uma camada lipídica.…”

“…Quando os melanócitos, responsáveis por produzir esses pigmentos, deixam de produzi-los, a fibra perde sua coloração, dando surgimento ao cabelo branco. A estrutura mais interna, a medula, geralmente está presente apenas em pelos grossos, como pelos da barba, assim não apresentam relevância para o uso de cosméticos capilares (PHILIPSEN et al, 2021).…”