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Open AccessFeature PaperArticle

A Study on Photostability of Amphetamines and Ketamine in Hair Irradiated under Artificial Sunlight

Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
Legal Medicine and Toxicology, University Hospital of Padova, 35121 Padova, Italy
School of Specialization in Legal Medicine, University Hospital of Padova, 35121 Padova, Italy
Authors to whom correspondence should be addressed.
Brain Sci. 2018, 8(6), 96;
Received: 29 April 2018 / Revised: 23 May 2018 / Accepted: 24 May 2018 / Published: 28 May 2018
Drugs incorporated into hair are exposed to the environment, and cosmetic and chemical treatments, with possible decreases in their content. Knowledge concerning the effect of sunlight on drug content in hair can be helpful to forensic toxicologists, in particular, when investigating drug concentrations above or below pre-determined cut-offs. Twenty authentic positive hair samples were selected which had previously tested positive for amphetamines and/or ketamine. Washed hair were divided into two identical strands, with the former exposed at 765 W/m2 (300–800 nm spectrum of irradiance) for 48 h in a solar simulator, and the latter kept in the dark. Hair samples were extracted and analyzed by liquid chromatography high-resolution mass spectrometry detection. The percentage of photodegradation was calculated for each analyte (i.e., amphetamine, methamphetamine, methylendioxyamphetamine, ketamine, and norketamine). In parallel, photodegradation processes of standard molecules dissolved in aqueous and organic solutions were studied. In 20 hair samples positive for the targeted analytes, exposure to artificial sunlight induced an appreciable decrease in drug concentrations. The concentration ranges in the non-irradiated hair samples were 0.01–24 ng/mg, and 65% of samples exhibited a decrease in post-irradiation samples, with reduction from 3% to 100%. When more drugs were present in the same hair sample (i.e., MDMA and ketamine) the degradation yields were compound dependent. A degradation product induced by irradiation of ketamine in aqueous and methanol solutions was identified; it was also found to be present in a true positive hair sample after irradiation. Ketamine, amphetamines, and their metabolites incorporated in the hair of drug users undergo degradation when irradiated by artificial sunlight. Only for ketamine was a photoproduct identified in irradiated standard solutions and in true positive irradiated hair. When decisional cut-offs are applied to hair analysis, photodegradation must be taken into account since sunlight may produce false negative results. Moreover, new markers could be investigated as evidence of illicit drug use. View Full-Text
Keywords: hair; solar light; photodegradation; amphetamines; MDMA; ketamine hair; solar light; photodegradation; amphetamines; MDMA; ketamine
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Miolo, G.; Tucci, M.; Menilli, L.; Stocchero, G.; Vogliardi, S.; Scrivano, S.; Montisci, M.; Favretto, D. A Study on Photostability of Amphetamines and Ketamine in Hair Irradiated under Artificial Sunlight. Brain Sci. 2018, 8, 96.

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