Hair analysis is an important and reliable resource for the assessment of alcohol or drug abstinence in both clinical and forensic toxicology. Recently, it has been demonstrated that hair oxidative cosmetic treatments lead to the reduction in incorporated xenobiotics in hair, such as ethyl glucuronide (EtG), a marker of alcohol abuse, and the formation of 1-H‐pyrrole‐2,3,5‐tricarboxylic acid (PTCA), a degradation product of melanin. The aim of the present study was to investigate PTCA trends in a large number of samples in order to evaluate the reliability of this biomarker in recognizing previous cosmetic treatment in forensic analyses. Therefore, a single-step extraction followed by an high-performance liquid chromatography--tandem mass spectrometry (HPLC--MS-MS) method was established and validated for the simultaneous determination of EtG and PTCA. This method was applied to 1,219 scalp hair samples from two groups, namely self-reported untreated and in vivo treated hair, exhibiting a concentration range of 6.7 to 440.0 pg/mg for EtG (mean 26.8 pg/mg, median 14.6 pg/mg) and 0.009 to 49.8 ng/mg for PTCA (mean 0.66 ng/mg, median 0.02 ng/mg). The PTCA content was significantly different among the two experimental groups, with the in vivo treated group showing significantly higher levels of PTCA than the untreated group. Finally, an in vitro bleaching was performed and the results confirmed that a strong hair oxidative treatment may negatively affect EtG test results (false negative), whereas the mean PTCA content increased showing statistically significant differences between untreated and in vitro oxidative treated samples. The present study suggests that the determination of PTCA in routine hair analysis procedure could be useful in order to discover previous cosmetic treatment including oxidation.

中文翻译：

---

PTCA（1-H-吡咯-2,3,5-三羧酸）作为氧化性头发护理的标记：分布，性别特征，与EtG的相关性和自我报告

头发分析是评估临床和法医毒理学中酒精或药物戒断的重要而可靠的资源。最近，已证明头发氧化美容治疗可减少头发中掺入的异种生物，例如乙基葡糖醛酸苷（EtG）（一种酗酒的标志物）和1-H-吡咯-2,3,5的形成。 -三羧酸（PTCA），黑色素的降解产物。本研究的目的是调查大量样品中的PTCA趋势，以评估该生物标记物在法医分析中识别先前美容治疗中的可靠性。所以，建立了一步萃取，然后进行高效液相色谱-串联质谱（HPLC-MS-MS）的方法，并验证了EtG和PTCA的同时测定方法。该方法适用于两组的1,219例头皮头发样本，即未经报告的自我报告和未经报告的头发。经体内处理的头发，EtG的浓度范围为6.7至440.0 pg / mg（平均26.8 pg / mg，中位数为14.6 pg / mg），PTCA的浓度范围为0.009至49.8 ng / mg（平均0.66 ng / mg，中位数0.02 ng） / mg）。在两个实验组之间，PTCA含量显着不同，体内治疗组的PTCA水平明显高于未治疗组。最后，进行了体外漂白，结果证实强力的头发氧化处理可能会对EtG测试结果产生负面影响（假阴性），而平均PTCA含量增加，显示未经处理和体外的统计学差异氧化处理的样品。本研究表明，在常规的头发分析程序中测定PTCA可能对发现以前的包括氧化在内的美容治疗很有用。